DESCRIPTION

Air Conditioner

Technical Field

[0001] The present invention relates to an air conditioner having a function of sterilizing an interior of an indoor unit.

Background Art

[0002] Conventionally, an indoor unit of an air conditioner has suction openings defined in a front wall and an upper wall of a main body thereof to inhale indoor air into the indoor unit and a discharge opening defined in a lower portion of the main body to discharge air inside the indoor unit into a room. Also, the indoor unit accommodates an air filter, a heat exchanger and a fan therein. Air inhaled through the suction openings passes through the air filter for dust removal and is heat-exchanged by the heat exchanger before the fan discharges the heat-exchanged air into the room through the discharge opening.

[0003] In the indoor unit of the air conditioner of the above-described construction, because indoor air together with, for example, airborne dust is inhaled into to the indoor unit, the dust is likely to adhere to wall surfaces inside the indoor unit, the fan, the heat exchanger and the like. The adherent dust contains microorganisms such as, for example, bacteria or molds, which are likely to grow proliferously within the indoor unit. In particular, immediately after a cooling operation has been brought to a stop, when water (dew condensation water) condensed on a surface of the heat exchanger vaporizes in the indoor unit to
thereby increase a humidity inside the indoor unit, microorganisms are likely to grow
proliferously.

[0004] To combat this, an air conditioner having a purification unit that generates ozone in the indoor unit to restrain reproduction of microorganisms has been proposed (see, for example, Patent Document 1).

Patent Document(s)

[0005] • Patent Document 1: Japanese Laid-Open Patent Publication No. 6-272888

Summary of the Invention

Problems to be solved by the Invention

[0006] However, if the interior of the indoor unit is exposed to ozone generated by the purification unit for long periods, a problem arises that component parts within the indoor unit are deteriorated by the oxidation effect of ozone.

[0007] Ozone (O3) is an unstable gas and gradually decomposes to become stable oxygen (02) at ordinary temperatures, but a rate of ozone decomposition reduces in a low-humidity or low-temperature environment. Accordingly, during dry winter months, for example, ozone generated by the purification unit is likely to remain in the substantially hermetically closed indoor unit for long periods. As a result, the component parts within the indoor unit are exposed to ozone for long periods.

[0008] In particular, in applications where the purification unit is designed to generate ozone utilizing electric discharge such as corona discharge, an amount of ozone generation increases in a low-humidity environment. Accordingly, during dry winter months, if the purification unit of this kind is used to generate ozone, high levels of ozone is likely to remain within the indoor unit for long periods.

[0009] In view of the above, the present invention is intended to reduce deterioration of component parts inside the indoor unit that may be caused by ozone remaining in the indoor unit.
Means to Solve the Problems

[0010] In order to achieve the above object, the invention has the following constitutions. [0011]
According to an aspect of the invention, there is provided an air conditioner according to the present invention includes an indoor unit, a fan accommodated in the indoor unit, and a purification unit accommodated in the indoor unit to generate at least ozone by means of electric discharge for purification of an interior of the indoor unit. After an air conditioning operation has been brought to a stop, the purification unit is operated to purify the interior of the indoor unit for a predetermined time period, and after the purification unit has been brought to a stop, the fan is operated to discharge ozone within the indoor unit outside.

Effects of the Invention

[0012] According to the present invention, after the stop of operation of the purification unit, the fan is operated to discharge ozone, generated within the indoor unit by the purification unit, outside, thereby restraining ozone from remaining within the indoor unit. As a result, deterioration of component parts within the indoor unit of the air conditioner, which may be caused by ozone, can be restrained.

Brief Description of the Drawings

[0013]The above construction and features of the present invention will become apparent from the following description of preferred embodiments thereof with reference to the accompanying drawings, wherein:
Fig. 1 is a vertical sectional view of an indoor unit of an air conditioner according to a first embodiment of the present invention,
Fig. 2 is a block diagram of a control system employed in the air conditioner according to the first embodiment,
Fig. 3 is a process chart indicating operation of the air conditioner according to the first embodiment,
Figs. 4A and 4B are charts indicating an example of a relationship between a residual ozone level in the indoor unit and on/off settings of a fan in the first embodiment,
Fig. 5 is a process chart indicating operation of an air conditioner according to a fourth embodiment of the present invention,
Figs. 6A and 6B are charts indicating an example of a relationship between a relative humidity in an indoor unit and on/off settings of a fan in the fourth embodiment,
Fig. 7 is a schematic view of a purification unit mounted in an air conditioner according to a fifth embodiment of the present invention,
Fig. 8 is a vertical sectional view of an indoor unit of the air conditioner according to the fifth embodiment,
Fig. 9 is a graph indicating a relationship between a value of integral of a discharge current and a radius of curvature of a distal end of a discharge electrode,
Fig. 10 is a graph indicating a relationship among a rate of ozone generation, a rate of ion generation and the radius of curvature of the distal end of the discharge electrode,
Fig. 11 is a graph indicating a relationship between the radius of curvature of the distal end of the discharge electrode and an ozone level in the indoor unit,
Fig. 12 is a flowchart indicating a control flow of the purification unit according to the fifth embodiment,
Fig. 13 is a graph indicating a relationship between a cumulative discharge time and the radius of curvature of the distal end of the discharge electrode,
Fig. 14 is a graph indicating a relationship between the cumulative discharge time and a discharge current,
Fig. 15 is a flowchart indicating a control flow of a purification unit according to a sixth embodiment of the present invention,
Fig. 16 is a flowchart indicating a control flow of a purification unit according to a seventh embodiment of the present invention,
Fig. 17 is a flowchart indicating a control flow of a purification unit according to an improved form of the seventh embodiment, and
Fig. 18 is a flowchart indicating a control flow of a purification unit according to another improved form of the seventh embodiment.

Embodiments for Carrying out the Invention

[0014] The present invention is directed to an air conditioner that includes an indoor unit, a fan accommodated in the indoor unit, and a purification unit accommodated in the indoor unit to generate at least ozone by means of electric discharge for purification of an interior of the indoor unit. In this air conditioner, after an air conditioning operation has been brought to a stop, the purification unit is operated to purify the interior of the indoor unit for a predetermined time period, and after the purification unit has been brought to a stop, the fan is operated to discharge ozone within the indoor unit outside.

[0015] The operation of the fan after the stop of operation of the purification unit causes ozone generated within the indoor unit by the purification unit to be discharged outside, thereby restraining ozone from remaining within the indoor unit. As a result, deterioration of component parts within the indoor unit of the air conditioner that may be caused by ozone can be restrained.

[0016] The air conditioner may further include a suction air temperature detecting means operable to detect a temperature of air inhaled into the indoor unit from within a room. In this case, an operating time period of the fan after purification, which indicates the operating time period of the fan after the stop of operation of the purification unit, is determined based on a temperature detected by the suction air temperature detecting means.

[0017] When the room temperature is high, i.e., when a cooling operation is conducted, ozone within the indoor unit decomposes at a high rate because of a high humidity within the indoor unit. Accordingly, only a small amount of ozone remains within the indoor unit after the stop of operation of the purification unit. On the other hand, when the room temperature is low, i.e., when a heating operation is conducted, ozone within the indoor unit decomposes at a low rate because of a low humidity within the indoor unit. Accordingly, a large amount of ozone remains within the indoor unit after the stop of operation of the purification unit. For this reason, the operating time period of the fan required to discharge ozone remaining within the indoor unit outside can be determined based on the temperature of indoor air detected by the suction air temperature detecting means. By doing so, the amount of ozone remaining in the indoor unit after the stop of operation of the purification unit can be restrained without operating the fan more than necessary.

[0018] The operating time period of the fan after purification may be determined based on an air conditioning operation mode before the start of operation of the purification unit.

[0019] In a case where the cooling operation is conducted as one mode of the air conditioning operation, ozone within the indoor unit decomposes at a high rate because of a high humidity within the indoor unit. Accordingly, only a small amount of ozone remains within the indoor unit after the stop of operation of the purification unit. On the other hand, in a case where the heating operation is conducted as another mode of the air conditioning operation, ozone within the indoor unit decomposes at a low rate because of a low humidity within the indoor unit. Accordingly, a large amount of ozone remains within the indoor unit after the stop of operation of the purification unit. For this reason, the operating time period of the fan required to discharge ozone remaining within the indoor unit outside can be determined based on the air conditioning operation mode before the start of operation of the purification unit. By doing so, the amount of ozone remaining in the indoor unit after the stop of operation of the purification unit can be restrained without operating the fan more than necessary.

[0020] The air conditioner may further include a louver operable to open and close a discharge opening defined in the indoor unit, through which air within the indoor unit is discharged outside. In this case, the purification unit is operated with the discharge opening closed by the louver and the fan is subsequently operated with the discharge opening opened at least partially by the louver.

[0021] Because ozone is generated within the hermetically closed or substantially hermetically closed indoor unit, the indoor unit can be filled with ozone within a short period of time, thus resulting in a reduction in the operating time period of the purification unit. Also, ozone filled in the indoor unit is discharged outside by operating the fan with the discharge opening opened at least partially by the louver. Because the discharge opening is opened at least partially, a user can visually know the operation of the fan, which relieves a feeling of strangeness the user may feel after completion of the air conditioning operation.

[0022] After the stop of operation of the purification unit, a heating operation may be conducted and, at the same time, the fan may be operated.

[0023] The heating operation after the stop of operation of the purification unit increases the temperature inside the indoor unit to thereby activate ozone decomposition. Because ozone within the indoor unit is discharged outside by the fan with progressing ozone decomposition, the amount of ozone remaining in the indoor unit reduces rapidly compared with a case where no heating operation is conducted, thus making it possible to reduce the operating time period of the fan.

[0024] After the stop of a cooling operation, the fan may be operated to dry the interior of the indoor unit and after the stop of operation of the fan, operation of the purification unit may be started to purify the interior of the indoor unit.

[0025] After the stop of the cooling operation and before the start of operation of the purification unit, ozone decomposition that may be caused by moisture contained in air is restrained by drying the interior of the indoor unit with the use of the fan. As a result, ozone generated by the purification unit diffuses over the interior of the indoor unit to entirely sterilize the interior of the indoor unit.

[0026] The air conditioner may further include a heat exchanger accommodated in the indoor unit, a suction air temperature detecting means operable to detect a temperature of air inhaled into the indoor unit from within the room, and a heat exchanger temperature detecting means operable to detect a temperature of the heat exchanger. In this case, an operating time period of the fan before purification, which indicates the operating time period of the fan after the stop of the cooling operation and before the start of purification by the purification unit, may be determined based on a temperature detected by the suction air temperature detecting means and a temperature detected by the heat exchanger temperature detecting means.

[0027] By determining the operating time period of the fan based on the temperature of indoor air and the temperature of the heat exchanger so that the humidity inside the indoor unit may become an optimum humidity for ozone sterilization, the interior of the indoor unit can be fully dried irrespective of detailed settings of the cooling operation of the air conditioner.

[0028] The air conditioner may further - include an outdoor temperature detecting means operable to detect an outdoor temperature. In this case, the operating time period of the fan before purification is increased or decreased based on a temperature detected by the outdoor temperature detecting means.

[0029] Based on a value of the outdoor temperature, the operating conditions of a compressor in an outdoor unit of the air conditioner and the amount of dew condensation water adhering to the heat exchanger in the indoor unit can be correctly perceived. Accordingly, the operating time period of the fan required to optimize the humidity inside the indoor unit can be correctly determined.

[0030] The air conditioner may further include a louver operable to open and close a discharge opening defined in the indoor unit, through which air within the indoor unit is discharged outside. In this case, after the stop of the cooling operation of the air conditioner, the fan is operated with the discharge opening opened at least partially by the louver and the purification unit is subsequently operated with the discharge opening closed by the louver.

[0031] Because ozone is generated within the hermetically closed or substantially hermetically closed indoor unit, the indoor unit can be filled with ozone within a short period of time, thus resulting in a reduction in the operating time period of the purification unit. Also, the interior of the indoor unit is dried by operating the fan with the discharge opening opened at least partially by the louver. Because the discharge opening is opened at least partially, a user can visually know the operation of the fan, which relieves a feeling of strangeness the user may feel after completion of the cooling operation.

[0032] The purification unit may include an electric discharge portion, which includes a discharge electrode having a sharp distal end to discharge electricity for ozone generation, and a controller operable to control electric discharge of the electric discharge portion to generate an amount of ozone within a predetermined range based on a radius of curvature of the distal end of the discharge electrode.

[0033] Even if the radius of curvature of the distal end of the discharge electrode varies over time, the electric discharge of the electric discharge portion for ozone generation is controlled based on the radius of curvature of the distal end of the discharge electrode, thus making it possible to generate an amount of ozone within the predetermined range and accordingly restrain deterioration of component
parts within the indoor unit that may be caused by ozone.

[0034] The radius of curvature of the distal end of the discharge electrode may be determined based on a cumulative discharge time of the electric discharge portion.

[0035] The radius of curvature of the distal end of the discharge electrode can be easily determined based on the cumulative discharge time.

[0036] Alternatively, the radius of curvature of the distal end of the discharge electrode may be determined based on a value of integral of a discharge current.

[0037] Because the value of integral of the discharge current is associated with a volume of wear of the distal end of the discharge electrode, the radius of curvature of the distal end of the discharge electrode can be highly accurately determined based on the value of integral of the discharge current.

[0038] The controller may control a running rate of the electric discharge portion to maintain an amount of ozone generation within a predetermined range.

[0039] The control of the electric discharge portion by the running rate allows the amount of ozone generation to be inexpensively adjusted within the predetermined range compared with a case where a voltage applied to the discharge electrode is controlled.

[0040] The controller may control the running rate of the electric discharge portion to be zero when the radius of curvature of the distal end of the discharge electrode reaches a predetermined critical radius of curvature of the distal end.

[0041] When the radius of curvature of the distal end of the discharge electrode reaches the predetermined critical radius of curvature of the distal end, the running rate of the electric discharge portion is rendered to be zero, i.e., the electric discharge is stopped to thereby control the amount of ozone generation so as not to cause any serious deterioration of the component parts within the indoor unit, thus making it possible to restrain failure from arising in the indoor unit of the air conditioner.

[0042] The air conditioner may further include a fuse that melts when a discharge current flows through the electric discharge portion and a value of integral thereof reaches a predetermined critical value of integral of the discharge current. In this case, when the fuse melts, the running rate of the electric discharge portion becomes zero.

[0043] Because the fuse acts to mechanically stop the electric discharge of the electric discharge portion, the purification unit (that is, air conditioner) is high in reliability.

[0044] The controller may control a discharge time of the electric discharge portion to maintain an amount of ozone generation within a predetermined range.

[0045] The amount of ozone generation can be easily controlled within the predetermined range by controlling the electric discharge portion using the discharge time.

[0046] The controller may control the discharge time of the electric discharge portion to be zero when the radius of curvature of the distal end of the discharge electrode reaches a predetermined critical radius of curvature of the distal end.

[0047] When the radius of curvature of the distal end of the discharge electrode reaches the predetermined critical radius of curvature of the distal end, the discharge time of the electric discharge portion is rendered to be zero, i.e., the electric discharge is stopped to thereby control the amount of ozone generation so as not to cause any serious deterioration of the component parts within the indoor unit, thus making it possible to restrain failure from arising in the indoor unit of the air conditioner.

[0048] The air conditioner may conduct a dust-collecting operation to discharge ions generated by the electric discharge portion to the interior of the room.

[0049] Dust contained in indoor air is electrically charged in the presence of ions and the electrically-charged dust can be collected in the indoor unit.

[0050] When the air conditioner conducts the dust-collecting operation, it is preferable that the electric discharge portion be located in an air passageway or adjacent thereto.

[0051] Ozone generated by the electric discharge portion of the purification unit can easily diffuse within the indoor unit through the air passageway. Also, many of ions generated by the electric discharge portion of the purification unit are discharged to the interior of the room through the air passageway.

[0052] The electric discharge portion may include a discharge electrode having a distal end, to which a negative potential is applied, and an opposite electrode confronting the distal end of the discharge electrode, a positive potential being applied to the opposite electrode. The opposite electrode is positioned on an air passageway side relative to the discharge electrode to allow an ionic wind generated by the electric discharge portion to flow within the indoor unit through the air passageway.

[0053] The arrangement in which the opposite electrode of the electric discharge portion is positioned on the air passageway side relative to the discharge electrode allows ozone generated by the electric discharge portion to efficiently move to the interior of the indoor unit by making use of an ionic wind flowing from the discharge electrode toward the opposite electrode. As a result, ozone diffuses over the interior of the indoor unit.

[0054] Embodiments of the present invention are described hereinafter with reference to the drawings, but the present invention is not limited to the embodiments.

[0055] (Embodiment 1) Fig. 1 is a vertical sectional view of an indoor unit of an air conditioner according to a first embodiment of the present invention. A construction of the air conditioner according to the first embodiment is explained hereinafter with reference to Fig. 1.

[0056] As shown in Fig. 1, the indoor unit of the air conditioner includes a main body 1 that has suction openings 2 defined in a front wall and an upper wall thereof to inhale indoor air into the main body 1 and a discharge opening 3 defined in a lower portion thereof to discharge air inside the main body 1 into a room. The suction openings 2 and the discharge opening 3 communicate with each other through an air passageway, in which an air filter 4 for removing dust contained in air inhaled through the suction openings 2, a fan 5 driven by a fan motor (not shown), and a heat exchanger 6 for exchanging heat with air are provided.

[0057] During an air conditioning operation of the air conditioner, air inhaled through the suction openings 2 in the main body 1 passes through the air filter 4, which collects dust contained in the air. The air filter 4 is interposed between the suction openings 2 and the heat exchanger 6 so as to cover a surface of the heat exchanger 6 confronting the suction openings 2.

[0058] Having passed through the air filter 4, the air passes through the heat exchanger 6 to exchange heat with the heat exchanger 6. That is, the air is cooled or heated by the heat exchanger 6. After heat exchange, the air is discharged into the room through the discharge opening 3 by the fan 5. The air to be discharged is guided to a predetermined direction by a louver 7. The air conditioning operation is conducted in this way. The louver 7 is designed so as to be able to open and close the discharge opening 3 in the indoor unit.

[0059] The air conditioner also includes a purification unit 8 to sterilize the interior of the main body 1 of the indoor unit. The purification unit 8 is designed to generate ozone to sterilize the interior of the main body 1 of the indoor unit by making use of electric discharge such as, for example, corona discharge. The purification unit 8 employed in the first embodiment is not limited to a corona discharge type, but may be of any construction if ozone can be generated.

[0060] In the first embodiment, the purification unit 8 is placed between an upper portion of the heat exchanger 6 and the air filter 4 extending along the suction openings 2. The purification unit 8 may be placed at an arbitrary position in the vicinity of, for example, the discharge opening 3 or the fan 5. By way of example, the purification unit 8 may be placed in the air passageway adjacent to the discharge opening 3. However, in order to sterilize the air filter 4 located at an upper portion inside the main body 1 of the indoor unit using ozone that has a higher specific gravity than air, it is preferable that the purification unit 8 be disposed at an upper portion inside the main body 1 of the indoor unit and in the vicinity of the air filter 4. Also, in order not to reduce an air supply performance of the air conditioner, it is preferable that a distance between the purification unit 8 and the fan 5 be lengthened. A reduction in air supply performance of the air conditioner can be curbed by placing the purification unit 8 between an upper portion of the heat exchanger 6 and the air filter 4.

[0061] It is to be noted that the position of the purification unit 8 according to the first embodiment in a longitudinal direction (horizontal direction) of the air conditioner is not limited.

[0062] Fig. 2 is a block diagram of a control system employed in the air conditioner according to the first embodiment. A controller 9 of the air conditioner includes a suction air temperature detecting means 10 for detecting a temperature of air inhaled into the indoor unit and an operation switching means 11 for switching an air conditioning operation. The controller 9 controls the fan 5, the louver 7, the purification unit 8, a compressor 12 and the like based on an input from the suction air temperature detecting means 10 and that from the operation switching means 11.

[0063] The suction air temperature detecting means 10 detects the temperature of air inhaled into the main body 1 of the indoor unit from within the room. To this end, the suction air temperature detecting means 10 is disposed at a position where air having passed through the air filter 4 flows and, for example, between the air filter 4 and the heat exchanger 6. The temperature of the inhaled air corresponds to nearly a room temperature.

[0064] Operation of the air conditioner according to the first embodiment is explained hereinafter. Fig. 3 is a process chart indicating the operation of the air conditioner.

[0065] As shown in Fig. 3, upon completion of the air conditioning operation of the air conditioner, the controller 9 brings the purification unit 8 into operation to initiate a purification operation with the discharge opening 3 closed by the louver 7. Ozone is generated by the operation of the purification unit 8. Because ozone has a higher specific gravity than air, ozone supplied from the purification unit 8, which is disposed at an upper portion inside the main body 1 of the indoor unit, is filled around the heat exchanger 6 and the fan 5 through the air passageway extending from the suction openings 2 to the discharge opening 3. Ozone acts to sterilize the interior of the main body 1 of the indoor unit.

[0066] Because the discharge opening 3 is closed by the louver 7, the interior of the main body 1 of the indoor unit is hermetically or substantially hermetically closed and, accordingly, the entire main body 1 can be effectively filled with ozone within a short period of time, thus making it possible to reduce an operating time of the purification unit 8 (time period of the purification operation).

[0067] After a lapse of a predetermined time period of the purification operation, the controller 9 brings the purification unit 8 to a stop to terminate the purification operation and initiates an air supply operation in which the fan 5 is activated with the discharge opening 3 opened at least partially by the louver 7.

[0068] When the fan 5 is activated after completion of the purification operation, it is preferable that the discharge opening 3 be opened at least partially by the louver 7 because a user can visually know the operation of the fan 5, which relieves a feeling of strangeness the user may feel after completion of the air conditioning operation.

[0069] After the purification unit 8 has been stopped (after the purification operation has been terminated), ozone filled in the main body 1 of the indoor unit is discharged outside by activating the fan 5 with the discharge opening 3 opened at least partially by the louver 7. By doing so, component parts within the main body 1 of the indoor unit are restrained from being exposed to ozone for long periods, thus making it possible to reduce deterioration of the component parts that may be caused by ozone.

[0070] It is preferred that a time period during which the fan 5 is in operation after completion of the purification operation (operating time period after purification) be determined based on the temperature of inhaled air (room temperature) detected by the suction air temperature detecting means 10. A concentration of ozone remaining in the main body 1 of the indoor unit after completion of the operation of the purification unit 8 can be predicted based on the temperature of the inhaled air. The operating time period of the fan 5 (operating time period after purification) is calculated to allow the remaining ozone to be completely discharged outside the main body 1 of the indoor unit.

[0071] Although the amount of ozone generation of the purification unit 8 differs depending on a discharge method or construction, it is explained, taking as

an example a purification unit 8 that is of, for example, a corona discharge type and designed to allow the residual ozone concentration in the indoor unit to become about 0.1 ppm after the purification unit 8 has been operated for two hours at a room temperature of 20°C.

[0072] In summer (in an environment of a room temperature of, for example, 25°C to 30°C), if the purification unit 8 is operated for two hours after completion of an air conditioning operation, i.e., a cooling operation, the residual ozone concentration in the main body 1 of the indoor unit is about 0.03 ppm after the purification unit 8 has been stopped. In this case, if the fan 5 is operated for, for example, five minutes after the stop of operation of the purification unit 8, the residual ozone in the main body 1 of the indoor unit is completely discharged outside. After the cooling operation has been stopped, dew condensation water condensed on a surface of the heat exchanger 6 vaporizes and, accordingly, the humidity inside the main body 1 of the indoor unit is relatively high. Because ozone decomposition is accelerated in conditions of high humidity, the operating time period of the fan 5 for discharging ozone outside can be reduced.

[0073] On the other hand, in winter (in an environment of a room temperature of, for example, 10°C to 15°C), if the purification unit 8 is operated for two hours after completion of an air conditioning operation, i.e., a heating operation, the residual ozone concentration in the main body 1 of the indoor unit is about 0.2 ppm after the purification unit 8 has been stopped. In this case, if the fan 5 is operated for, for example, ten minutes after the stop of operation of the purification unit 8, the residual ozone in the main body 1 of the indoor unit is completely discharged outside. After the heating operation has been stopped, because the temperature inside the main body 1 of the indoor unit is high, the interior of the main body 1 is dry and, accordingly, the humidity inside the main body 1 of the indoor unit is relatively low. Because ozone decomposition is slow in conditions of low humidity, the operating time period of the fan 5 for discharging ozone outside must be increased.

[0074] Fig. 4 is a chart indicating an example of a relationship between a residual ozone concentration within the main body 1 of the indoor unit, which is predicted based on the inhaled air temperature (room temperature), and on/off settings of the fan 5. As shown in Fig. 4(a), if the inhaled air temperature (room temperature) is low, the residual ozone concentration (C1) is predicted to be relatively high. Accordingly, the operating time period of the fan 5 is set longer with a reduction in inhaled air temperature (room temperature). On the other hand, as shown in Fig. 4(b), if the inhaled air temperature (room temperature) is high, the residual ozone concentration (C2) is predicted to be relatively low. Accordingly, the operating time period of the fan 5 is set shorter with an increase in inhaled air temperature (room temperature).

[0075] As described above, the residual ozone concentration in the main body 1 of the indoor unit can be predicted by detecting the inhaled air temperature (room temperature). Based on the residual ozone concentration so predicted, the operating time period of the fan 5 after the stop of operation of the purification unit 8 is appropriately determined to thereby restrain ozone from remaining in the main body 1 of the indoor unit after the stop of operation of the purification unit 8, thereby making it possible to reduce deterioration of the component parts within the indoor unit that may be caused by ozone. Also, because the fan 5 is operated for an appropriate time period, i.e., the fan 5 is not operated more than necessary, power consumption can be reduced (an energy saving effect can be obtained).

[0076] Although a speed of the fan 5 after the stop of operation of the purification unit 8 is not limited in the present invention, the operating time period of the fan 5 or a time period during which ozone is discharged from the main body 1 of the indoor unit can be reduced with an increase in speed of the fan 5.

[0077] (Embodiment 2) An air conditioner according to a second embodiment differs from the air conditioner according to the first embodiment in that in the former the operating time period of the fan 5 after the stop of operation of the purification unit 8 (operating time period after purification) is determined based on an operation mode of the air conditioner before operation of the purification unit 8 is initiated.

[0078] The air conditioner according to the second embodiment is next explained. The same component parts as those in the first embodiment are designated by the same signs and explanation thereof is omitted.

[0079] As in the first embodiment, upon completion of the air conditioning operation of the air conditioner, the controller 9 brings the purification unit 8 into operation to initiate a purification operation with the discharge opening 3 closed by the louver 7. The interior of the main body 1 of the indoor unit is sterilized by ozone generated by the purification unit 8.

[0080] After a lapse of a predetermined time period of the purification operation, the controller 9 brings the purification unit 8 to a stop to terminate the purification operation and then initiates an air supply operation in which the fan 5 is activated with the discharge opening 3 opened at least partially by the louver 7. The operating time period of the fan 5 (operating time period after purification) is determined based on an air conditioning operation mode of the air conditioner switched by the operation switching means 11 and, in particular, on an air conditioning operation mode such as, for example, a heating operation or a cooling operation before operation of the purification unit 8 is initiated.

[0081] By way of example, if the air conditioning operation before operation of the purification unit 8 is initiated (before the start of the purification operation) is the cooling operation, after the cooling operation has been stopped, dew condensation water condensed on a surface of the heat exchanger 6 vaporizes in the main body 1 of the indoor unit and, accordingly, the humidity inside the main body 1 of the indoor unit is high. Ozone decomposition is accelerated in conditions of high humidity inside the indoor unit. Accordingly, if the air conditioning operation before the start of the purification operation is the cooling operation, the residual ozone in the main body 1 of the indoor unit can be discharged outside by operating the fan 5 for only a short period of time.

[0082] On the other hand, if the air conditioning operation before operation of the purification unit 8 is initiated (before the start of the purification operation) is the heating operation, the temperature inside the main body 1 of the indoor unit becomes high and, hence, the interior of the main body 1 is dry and the humidity inside the main body 1 is accordingly low. Because ozone decomposition is slow in conditions of low humidity, if the air conditioning operation before operation of the purification unit 8 is initiated is the heating operation, the residual ozone in the main body 1 of the indoor unit is discharged outside by operating the fan 5 for a sufficiently long period of time.

[0083] As described above, the operating time period of the fan 5 after the stop of operation of the purification unit 8 is appropriately determined based on the air conditioning mode of the air conditioner before operation of the purification unit 8 is initiated, thereby making it possible to restrain ozone from remaining in the main body 1 of the indoor unit after the stop of operation of the purification unit 8. As a result, deterioration of the component parts within the indoor unit that may be caused by ozone can be reduced. Also, because the fan 5 is not operated more than necessary, an energy saving effect can be obtained.

[0084] (Embodiment 3) An air conditioner according to a third embodiment differs from the air conditioner according to the first embodiment in that in the former the heating operation is conducted after the stop of operation of the purification unit 8.

[0085] The air conditioner according to the third embodiment is next explained. The same component parts as those in the first embodiment are designated by the same signs and explanation thereof is omitted.

[0086] As in the first embodiment, upon completion of the operation of the air conditioner, the controller 9 brings the purification unit 8 into operation to initiate a purification operation with the discharge opening 3 closed by the louver 7. The interior of the main body 1 of the indoor unit is sterilized by ozone generated by the purification unit 8.

[0087] After a lapse of a predetermined time period of the purification operation, the controller 9 brings the purification unit 8 to a stop to terminate the purification operation and then conducts the heating operation with the discharge opening 3 opened at least partially by the louver 7. That is, both the compressor 12 and the fan 5 are brought into operation. When the temperature inside the main body 1 of the indoor unit becomes high through the heating operation, decomposition of the residual ozone in the main body 1 is activated. Because ozone is discharged outside the main body 1 of the indoor unit by the fan 5 while accelerating ozone decomposition, the amount of ozone remaining in the indoor unit reduces rapidly compared with a case where no heating operation is conducted.

[0088] As described above, the heating operation conducted after the stop of operation of the purification unit 8 can restrain ozone from remaining in the main body 1 of the indoor unit after the stop of operation of the purification unit 8. As a result, not only can deterioration of the component parts within the indoor unit that may be caused by ozone be reduced, but the operating time period of the fan 5 can be also reduced.

[0089] (Embodiment 4) An air conditioner according to a fourth embodiment differs from the air conditioners according to the above-described embodiments in that in the former the fan 5 is operated to conduct an air supply operation in order to dry the interior of the main body 1 of the indoor unit after termination of the cooling operation of the air conditioner and before the start of purification (purification operation) of the interior of the main body 1 of the indoor unit by the purification unit 8.

[0090] The air conditioner according to the fourth embodiment is next explained. The same component parts as those in the above-described embodiments are designated by the same signs and explanation thereof is omitted.

[0091] The reason why the interior of the main body 1 of the indoor unit is dried by the fan 5 after termination of the cooling operation and before the start of operation of the purification unit 8 is first explained.

[0092] After termination of the cooling operation, dew condensation water condensed on a surface of the heat exchanger 6 vaporizes in the main body 1 of the indoor unit and, accordingly, the humidity inside the main body 1 of the indoor unit is high. In conditions of high humidity, ozone generated by the purification unit 8 is unlikely to diffuse over the interior of the main body 1 of the indoor unit.

[0093] More specifically, if ozone is soluble in water, ozone decomposition is accelerated with hydroxide ions as a catalyst and ozone is eventually decomposed into oxygen. Sterilization by ozone makes use of a strong oxidative power of radicals generated in a decomposition process of ozone. Such radicals are unstable and have a short life-span. For this reason, in order to entirely sterilize the interior of the main body 1 of the indoor unit using ozone, it is necessary to diffuse ozone over the interior of the main body 1 of the indoor unit before ozone begins to decompose.

[0094] In conditions of high humidity, however, ozone generated by the purification unit 8 reacts with moisture contained in air to thereby accelerate ozone decomposition. Because of this, ozone is unlikely to diffuse over the interior of the main body 1 of the indoor unit.

[0095] Also, in applications where the purification unit 8 is designed to generate ozone by making use of electric discharge such as, for example, corona discharge, ozone generation by the electric discharge in conditions of high humidity is hindered, thus resulting in a reduction in the amount of ozone generation. Because of this, the ozone generated merely remains in the vicinity of the purification unit 8 and is accordingly unlikely to diffuse over the interior of the main body 1 of the indoor unit.

[0096] For the above-described reason, in the air conditioner according to the fourth embodiment, upon completion of the cooling operation, the interior of the main body 1 of the indoor unit is dried by the fan 5 before the purification unit 8 generates ozone.

[0097] As shown in Fig. 5 depicting a process chart of the operation of the air conditioner according to the fourth embodiment, upon completion of the cooling operation, the controller 9 controls the fan 5 to conduct an air supply operation before operation of the purification unit 8 is initiated.

[0098] More specifically, upon completion of the cooling operation, the controller 9 operates the fan 5 with the discharge opening 3 opened at least partially by the louver 7.

[0099] When the fan 5 is brought into operation upon completion of the cooling operation, it is preferred that the discharge opening 3 be opened at least partially by the louver 7 because a user can visually see the operation of the fan 5, which relieves a feeling of strangeness the user may feel upon completion of the cooling operation.

[0100] It is also preferred that the operating time period of the fan 5 from the stop of the cooling operation to the start of purification by the purification unit 8 (operating time period before purification), i.e., the time period required for drying be determined based on the suction air temperature (room temperature) detected by the suction air temperature detecting means 10 and the temperature of the heat exchanger 6 detected by the heat exchanger temperature detecting means 13. Specifically, based on the suction air temperature (room temperature) and the temperature of the heat exchanger 6, the humidity inside the main body 1 of the indoor unit after completion of the cooling operation can be predicted. The operating time period of the fan 5 before purification is calculated so that thehumidity so predicted may become an optimum humidity suitable for the operation of the purification unit 8 (that is, a humidity at which ozone generated by the purification unit 8 can diffuse over the interior of the main body 1 of the indoor unit).

[0101] The relative humidity inside the main body 1 of the indoor unit can be predicted from a temperature difference between the suction air temperature (room temperature) and the temperature of the heat exchanger 6.

[0102] By way of example, if the air conditioner is operated to conduct the cooling operation for an hour at a set temperature of 16°C in a room of a temperature of 27°C and a relative humidity of 47%, the temperature difference between the suction air temperature (room temperature) and the temperature of the heat exchanger 6 exceeds 10°C after completion of the cooling operation and the relative humidity inside the main body 1 of the indoor unit is about 100%. If the fan 5 is operated for, for example, 30 minutes after completion of the one-hour cooling operation, the temperature difference between the suction air temperature (room temperature) and the temperature of the heat exchanger 6 becomes 2-3°C and the relative humidity inside the main body 1 of the indoor unit reduces to 80%. On the other hand, if the fan 5 is not operated, the relative humidity inside the main body 1 of the indoor unit is maintained at about 100% after completion of the cooling operation.

[0103] Fig. 6 depicts an example of a relationship between the relative humidity inside the main body 1 of the indoor unit, which is predicted based on the suction air temperature (room temperature) and the temperature of the heat exchanger 6, and on/off settings of the fan 5. As shown in Fig. 6(a), if the temperature difference between the suction air temperature (room temperature) and the temperature of the heat exchanger 6 is small, a relatively small amount of dew condensation water condenses on a surface of the heat exchanger 6 and, hence, the relative humidity (H1) inside the main body 1 of the indoor unit is predicted to be relatively low. For this reason, as the temperature difference between the suction air temperature (room temperature) and the temperature of the heat exchanger 6 reduces, the operating time period of the fan 5 is set shorter. On the other hand, as shown in Fig. 6(b), if the temperature difference between the suction air temperature (room temperature) and the temperature of the heat exchanger 6 is large, a relatively large amount of dew condensation water condenses on the surface of the heat exchanger 6 and, hence, the relative humidity (H2) inside the main body 1 of the indoor unit is predicted to be relatively high. For this reason, as the temperature difference between the suction air temperature (room temperature) and the temperature of the heat exchanger 6 increases, the operating time period of the fan 5 is set longer.

[0104] Also, an outdoor temperature detecting means (not shown) for detecting an outdoor temperature may be provided in an outdoor unit (not shown) of the air conditioner. In this case, the operating time period of the fan 5 before purification is increased or decreased (corrected) based on the outdoor temperature detected by the outdoor temperature detecting means.

[0105] Based on the outdoor temperature, an operating condition of the compressor 12 in the outdoor unit of the air conditioner and an amount of dew condensation water adhering to the heat exchanger 6 in the main body 1 of the indoor unit can be correctly perceived. The operating condition of the compressor 12 and, specifically, a frequency of the compressor 12 is determined based on a room temperature set by a user and an actual room temperature. The air conditioner according to the fourth embodiment is designed to increase or decrease (correct) the frequency of the compressor 12 based on the outdoor temperature. By doing so, the compressor 12 can be operated at a frequency which takes into account heat transfer from outdoor to indoor, thus making it possible to accurately control the actual room temperature to become equal to the set room temperature.

[0106] Also, based on the frequency (operating condition) of the compressor 12 at which the actual room temperature can be accurately controlled to the set room temperature, the temperature of the heat exchanger 6 in the main body 1 of the indoor unit can be calculated more accurately. Further, based on the more accurate temperature of the heat exchanger 6 so calculated and the room temperature, the amount of dew condensation water adhering to the heat exchanger 6 can be perceived more accurately. In addition, based on the more accurate amount of dew condensation water adhering to the heat exchanger 6, the operating time period of the fan 5 before purification can be calculated highly accurately to control the humidity inside the main body 1 of the indoor unit to an appropriate one.

[0107] As described above, based on a relationship among the outdoor temperature, the frequency of the compressor 12, the temperature of the heat exchanger 6, the amount of dew condensation water adhering to the heat exchanger 6 and the operating time period of the fan 5 before purification, the controller 9 of the air conditioner corrects more appropriately the operating time period of the fan 5 before purification from the outdoor temperature detected by the outdoor temperature detecting means. As such, the operating time period of the fan 5 before purification required to dry the interior of the main body 1 of the indoor unit so as to have an appropriate humidity can be highly accurately determined.

[0108] Upon completion of drying inside the main body 1 of the indoor unit by the fan 5, the controller 9 operates the purification unit 8 to initiate the purification operation with the discharge opening 3 closed by the louver 7.

[0109] As described above, after the stop of the cooling operation and before the start of operation of the purification unit 8, the interior of the main body 1 of the indoor unit is dried by the fan 5 so that ozone generated by the purification unit 8 may diffuse over the interior of the main body 1 of the indoor unit to entirely sterilize the interior of the main body 1. If the purification unit 8 is designed to generate ozone by electric discharge, a reduction in the amount of ozone generation of the purification unit 8 is restrained. Accordingly, ozone generated by the purification unit 8 diffuses over the interior of the main body 1 of the indoor unit without remaining in the vicinity of the purification unit 8.

[0110] Unlike the case after the stop of the cooling operation, after the stop of the heating operation, the humidity inside the main body 1 of the indoor unit is relatively low. Accordingly, after the stop of the heating operation, a need to dry the interior of the main body 1 of the indoor unit by means of the fan 5 prior to the operation of the purification unit 8 is low.

[0111] (Embodiment 5) An air conditioner according to a fifth embodiment differs from the air conditioners according to the above-described embodiments in that in the former the purification unit 8 is controlled in view of a secular change thereof.

[0112] The air conditioner according to the fifth embodiment is next explained. The same component parts as those in the above-described embodiments are designated by the same signs and explanation thereof is omitted.

[0113] The reason why the purification unit 8 is controlled in view of a secular change thereof is first explained.

[0114] The purification unit 8 increases the amount of ozone generation per unit time (rate of ozone generation) over time depending on a construction thereof. If the rate of ozone generation increases, the ozone concentration inside the main body 1 of the indoor unit increases excessively, thereby posing a problem that deterioration of the component parts within the indoor unit is accelerated or ozone odor is emitted in the vicinity of the indoor unit. Accordingly, it is necessary to control the purification unit 8 in view of the fact that the rate of ozone generation increases over time. Specifically, the purification unit 8 is controlled to restrain deterioration of the component parts within the indoor unit and generate an amount of ozone within a predetermined range that can sufficiently sterilize the interior of the main body 1 of the indoor unit without emitting ozone odor in the vicinity of the indoor unit.

[0115] With the use of a purification unit that is designed to discharge electricity on a discharge electrode having a sharp distal end for ozone generation, inventors of the present invention conducted various experiments and discovered that a secular change in shape of the distal end of the discharge electrode increased the rate of ozone generation over time.

[0116] Fig. 7 schematically depicts a construction of the purification unit 8 according to the fifth embodiment that may increase the rate of ozone generation over time. As shown in Fig. 7, the purification unit 8 according to the fifth embodiment includes an electric discharge portion 33 having a discharge electrode 31 and an opposite electrode 32 confronting a distal end 31a of the discharge electrode 31. This purification unit 8 also includes a high-voltage generating device 34 to apply a high voltage between the two electrodes of the electric discharge portion 33.

[0117] The distal end 31a of the discharge electrode 31 is sharply pointed and electric discharge occurs when an intense electric field is concentrated on the distal end 31a. As shown in Fig. 7, the opposite electrode 32 is made up of a plate-like member having a circular arc cross-section. The discharge electrode 31 is positioned such that the distal end 31a thereof is nearly equally separated from any points on a surface of the opposite electrode 32 as viewed in cross-section. This configuration allows an electric field to concentrate on the distal end 31a of the discharge electrode 31 to thereby enable effective electric discharge.

[0118] The discharge electrode 31 is made of, for example, stainless steel, nickel, aluminum, copper, tungsten or the like. Considering material workability, the use of stainless steel for the discharge electrode 31 is preferred. The sharper is the distal end 31a of the discharge electrode 31, the lower is the rate of ozone generation (amount of ozone generation per unit time is small). It is sufficient if a main body of the discharge electrode 31 has a diameter of 0.3 mm or more and 1 mm or less. If the diameter is less than 0.3 mm, a difference between the distal end and the main body is too small. If the diameter is greater than 1 mm, the discharge electrode 31 is hard to machine.

[0119] The opposite electrode 32 is similarly made of, for example, stainless steel, nickel, aluminum, copper, tungsten or the like. Considering material workability, the use of stainless steel for the opposite electrode 32 is preferred. It is sufficient if the opposite electrode 32 has a thickness of 0.3 mm or more and 2 mm or less. If the thickness is less than 0.3 mm, the opposite electrode 32 is low in strength and easily deforms during, for example, a manufacturing process. If the thickness is greater than 2 mm, the opposite electrode 32 is hard to machine.

[0120] The high-voltage generating device 34 applies a high voltage between the discharge electrode 31 and the opposite electrode 32. By way of example, the high-voltage generating device 34 is designed to apply a negative potential to the discharge electrode 31 and a positive potential to the opposite electrode 32. It is preferable that the voltage applied between the two electrodes of the electric discharge portion 33 by the high-voltage generating device 34 be less than, for example, 8 kV so as not to cause short circuit between the two electrodes. If the applied voltage is, for example, 10 kV, a spatial distance for insulation and a creepage distance for insulation are both required to be sufficiently long in consideration of safety, thus resulting in an increase in size of the purification unit 8.

[0121] The high-voltage generating device 34 is controlled by the controller 9. That is, the controller 9 controls electric discharge of the electric discharge portion 33 through the high-voltage generating device 34.

[0122] Preferably, the high-voltage generating device 34 includes, for example, a protection circuit to control an excessive current in consideration of safety.

[0123] The high-voltage generating device 34 may be designed to apply a positive potential to the discharge electrode 31 and a negative potential to the opposite electrode 32. In the practice of the present invention, a polarity of the potential applied to the discharge electrode 31 and that of the potential applied to the opposite electrode 32 are not limited insofar as electric discharge occurs to generate ozone.

[0124] In the purification unit 8, when a negative potential and a positive potential are applied to the discharge electrode 31 and the opposite electrode 32,respectively, electric discharge, specifically corona discharge occurs on the distal end 31a of the discharge electrode 31. That is, electrons are emitted from the distal end 31a of the discharge electrode 31 toward the opposite electrode 32.

[0125] The electrons emitted from the distal end 31a of the discharge electrode 31 are accelerated by an electric field. When the electrons impinge on gas molecules, kinetic energy is given to the gas molecules to thereby create an air current. Also, when the electrons impinge on oxygen molecules, molecular bonds thereof are cut off to thereby create oxygen atoms. Ozone is generated by such oxygen molecules and oxygen atoms. Further, when the electrons are trapped by gas particles, negatively-charged ion particles are created, thereby generating an ionic wind containing the minus ion particles. The ionic wind generated by applying a voltage between the discharge electrode 31 and the opposite electrode 32 flows from the discharge electrode 31 toward the opposite electrode 32.

[0126] The air conditioner may be designed to conduct a dust-collecting operation in which dust contained in indoor air is collected by minus ions created by the purification unit 8.

[0127] The dust-collecting operation is next explained. The dust-collecting operation is conducted by operating the fan 5 and the purification unit 8 with the discharge opening 3 opened by the louver 7. The dust-collecting operation may be conducted together with the cooling operation or the heating operation.

[0128] During the dust-collecting operation, the minus ions created by the purification unit 8 are supplied to an indoor space through the discharge opening 3 by the fan 5. The minus ions act to electrically charge dust contained in indoor air. The electrically-charged dust is sucked into the main body 1 of the indoor unit through the suction openings 2 and collected by the air filter 4. In order to increase a dust-collecting efficiency, the air filter 4 may be charged with a polarity opposite to the polarity of the electrically-charged dust using a voltage applying device (not shown).

[0129] Also, during the dust-collecting operation, it is preferred that the speed of the fan 5 be increased to rapidly discharge the ions created by the purification unit 8 into the indoor space before the ions neutralize within the main body 1 of the indoor unit. If dust collection is strongly desired, it is also preferred that the speed of the fan 5 be increased. With an increase in speed of the fan 5, an amount of ions to be discharged into the indoor space increases and, also, a volume of indoor air to be inhaled in the main body 1 of the indoor unit increases.

[0130] In applications where the dust-collecting operation is conducted using the ions created by the purification unit 8, it is preferred that the purification unit 8 be positioned, as shown in Fig. 8, in the air passageway that communicates the suction opening 2 with the discharge opening 3 or in the vicinity thereof. In particular, as shown in Fig. 8, it is preferred that the purification unit 8 be positioned in the vicinity of the discharge opening 3.

[0131] In order to allow ozone generated by the purification unit 8 to diffuse within the main body 1 of the indoor unit, i.e., to allow the ionic wind containing ozone to flow within the main body 1 of the indoor unit, it is preferred that the purification unit 8 be positioned in the main body 1 of the indoor unit such that the opposite electrode 32 is positioned on the air passageway side relative to the discharge electrode 31 (distal end 31a) (in a case where the discharge electrode 31 is negatively charged and the opposite electrode 32 is positively charged).

[0132] By such a construction, the ionic wind flows toward a center of the main body 1 of the indoor unit through the air passageway to allow ozone contained therein to diffuse within the main body 1 of the indoor unit. As a result, the fan 5, the heat exchanger 6 and the air filter 4 can be sufficiently sterilized by ozone.

[0133] In particular, if the purification unit 8 is disposed in the vicinity of the discharge opening 3 so as to direct the ionic wind upwardly, it becomes possible to diffuse ozone, which has a higher specific gravity than air, close to the air filter 4 positioned at an upper portion inside the main body 1 of the indoor unit.

[0134] A method of controlling the above-described purification unit 8 is next explained.

[0135] As described above, the inventors of the present invention discovered that a secular change in shape of the distal end 31a of the discharge electrode 31 increased the rate of ozone generation over time. Specifically, the inventors discovered that the rate of ozone generation increased due to a change in radius of curvature of the distal end 31a of the discharge electrode 31, which was caused by wear of the distal end 31 a. Accordingly, it is necessary to control electric discharge of the electric discharge portion 33 of the purification unit 8 based on the radius of curvature of the distal end 31a of the discharge electrode 31 so as to generate an amount of ozone within a predetermined range.

[0136] In order to control electric discharge of the electric discharge portion 33 of the purification unit 8 based on the radius of curvature of the distal end 31a of the discharge electrode 31 so as to generate an amount of ozone within the predetermined range, the inventors discovered, through various experiments, a relationship between the radius of curvature of the distal end 31a of the discharge
electrode 31 and the rate of ozone generation or the rate of ion generation.

[0137] Fig. 9 depicts a relationship between a value of integral of a discharge current and the radius of curvature of the distal end 31a of the discharge electrode 31. In a graph of Fig. 9, a horizontal axis indicates the value of integral of the discharge current and a vertical axis indicates the radius of curvature of the distal end 31a of the discharge electrode 31. The discharge current is an electric current flowing at the time of electric discharge and is obtained by detecting, for example, a current value flowing between the discharge electrode 31 and the high-voltage generating device 34.

[0138] As shown in Fig. 9, the radius of curvature of the distal end 31a of the discharge electrode 31 increases monotonically with an increase in value of integral of the discharge current. More specifically, at an early stage, i.e., until the value of integral of the discharge current reaches Q0.i, the radius of curvature rapidly increases up to about 0.1 mm. Thereafter, the radius of curvature increases gradually. The reason for this is that the electric discharge causes wear of the distal end 31a of the discharge electrode 31 so as to increase the radius of curvature thereof. At the early stage in which the radius of curvature is small, slight wear causes a large change in radius of curvature.

[0139] Fig. 9 reveals that a volume of wear of the distal end 31a of the discharge electrode 31 is associated with the value of integral of the discharge current. With the use of the relationship shown in Fig. 9, the radius of curvature of the distal end 31a of the discharge electrode 31 can be determined based on the value of integral of the discharge current.

[0140] Fig. 10'depicts a relationship among an amount of ozone generation per unit time generated by the electric discharge portion 33 (that is, the rate of ozone generation), an amount of ion generation per unit time (that is, the rate of ion generation) and the radius of curvature of the distal end 31a of the discharge electrode 31. In a graph of Fig. 10, a horizontal axis indicates the radius of curvature of the distal end 31a of the discharge electrode 31, a left- side vertical axis indicates the rate of ozone generation, and a right- side vertical axis indicates the rate of ion generation.

[0141] As shown in Fig. 10, the rate of ozone generation (solid line) increases relatively rapidly until the radius of curvature of the distal end 31a of the discharge electrode 31 reaches 0.1 mm. Thereafter, the rate of ozone generation increases gradually until the radius of curvature of the distal end 31a of the discharge electrode 31 reaches rendi- If the radius of curvature of the distal end 31a of the discharge electrode 31 exceeds rendi, the rate of ozone generation reduces rapidly. If the radius of curvature of the distal end 31a of the discharge electrode 31 reaches rend2. the rate of ozone generation becomes zero.

[0142] It is conceivable that the reason for the increase in rate of ozone generation is that wear progressing with the electric discharge increases the radius of curvature of the distal end 31a of the discharge electrode 31 to thereby enlarge a discharge field around the distal end 31a. It is also conceivable that if the radius of curvature of the distal end 31a of the discharge electrode 31 exceeds rendi, electric discharge is unlikely to occur because an electric field is weakened excessively.

[0143] On the other hand, the rate of ion generation (dotted line) changes little until the radius of curvature of the distal end 31a of the discharge electrode 31 reaches rendi- If the radius of curvature of the distal end 31a of the discharge electrode 31 exceeds rendi. the rate of ion generation reduces rapidly. If the radius of curvature of the distal end 31a of the discharge electrode 31 reaches rend2. the rate of ion generation becomes zero. As with a rapid reduction in rate of ion generation, it is conceivable that a rapid reduction in rate of ion generation is due to the weakened electric field around the distal end 31a of the discharge electrode 31.

[0144] As shown in Fig. 10, as the radius of curvature of the distal end 31a of the discharge electrode 31 increases, the rate of ion generation changes little, but the rate of ozone generation increases monotonically. Also, both the rate of ozone generation and the rate of ion generation reduce rapidly if the radius of curvature of the distal end 31a of the discharge electrode 31 exceeds rendi.

[0145] The secular change of only the purification unit 8 has been discussed above and a secular change when the purification unit 8 has been installed in the indoor unit of the air conditioner is discussed hereinafter.

[0146] Fig. 11 depicts a relationship between the radius of curvature of the distal end 31a of the discharge electrode 31 and an ozone concentration in the indoor unit. In a graph of Fig. 11, a horizontal axis indicates the radius of curvature of the distal end 31a of the discharge electrode 31 and a vertical axis indicates the ozone concentration in the indoor unit.

[0147] As shown in Fig. 11, as the radius of curvature of the distal end 31a of the discharge electrode 31 changes, the ozone concentration in the indoor unit changes in the same manner as the rate of ozone generation shown in Fig. 10. However, a rate of increase in ozone centration at an initial ozone concentration Cunio3o is greater than that in rate of ozone generation at an initial rate of ozone generation V03o- It is conceivable that the reason for this is that ozone leakage from the interior of the indoor unit to the exterior occurs and if the rate of ozone generation in the electric discharge portion 33 increases, a contribution ratio of ozone leakage to the reduction in ozone concentration reduces relatively.

[0148] Accordingly, it can be seen that the secular change in ozone concentration within the indoor unit is greater than the secular change in rate of ozone generation of the purification unit 8 shown in Fig. 10. Because of this, ozone odor may be emitted in the vicinity of the indoor unit or component parts within the indoor unit may be deteriorated with long-term use of the air conditioner.

[0149] The component parts within the indoor unit that are likely to be deteriorated by ozone are those made of, in particular, rubber. The component parts made of rubber having double bonds may be deteriorated by being exposed to ozone. By way of example, if a damping rubber of the fan 5 is deteriorated in the presence of, for example, cracks, an abnormal noise, a vibration or the like may be generated. Butyl rubber, nitrile rubber, chloroprene rubber, silicone rubber, ethylene-propylene rubber or the like is used as a rubber material to be used for the component parts within the indoor unit. Although ethylene-propylene rubber and silicone rubber have a resistance to ozone, the former is limited in use in terms of damping properties and the latter is limited in use in terms of cost. Accordingly, butyl rubber, nitrile rubber or chloroprene rubber added with an additive agent having a resistance to ozone is generally used. However, even a component part made of such a rubber material is deteriorated when excessively exposed to ozone.

[0150] Also, a surface of a component part made of a metallic material may become eroded in the presence of ozone. By way of example, if an electric contact becomes eroded, an electric resistance thereof may increase. If a sliding portion of a drive source such as, for example, a motor becomes eroded, a driving efficiency thereof may reduce.

[0151] Based on the relationship among the value of integral of the discharge current, the radius of curvature of the distal end 31a of the discharge electrode 31, and the ozone concentration within the indoor unit referred to above, the controller 9 is designed to control the purification unit 8 to generate an amount of ozone within a predetermined range. A control flow of the purification unit 8 to be executed by the controller 9 is explained hereinafter with reference to Fig. 12. Fig. 12 depicts a control flow to be executed during the purification operation.

[0152] As shown in Fig. 12, firstly at step S1, the controller 9 calculates the value of integral of the discharge current. Specifically, the controller 9 periodically samples the discharge current and calculates the value of integral of the discharge current by integrating sampled values of the discharge current with respect to time. Because a change in current value is small, it is sufficient if the sampling is conducted at time intervals within a range of a second to several minutes.

[0153] At step S2, the controller 9 determines a radius of curvature of the distal end 31a of the discharge electrode 31 corresponding to the value of integral of the discharge current calculated at step S1 based on the relationship shown in Fig. 9 between the value of integral of the discharge current and the radius of curvature of the distal end 31a of the discharge electrode 31. By way of example, a radius of curvature rx of the distal end 31a of the discharge electrode 31 corresponding to a value of integral Qx of the discharge current is determined, thereby rendering a current radius of curvature of the distal end 31a of the discharge electrode 31 to become known.

[0154] At step S3, the controller 9 determines an ozone concentration in the indoor unit corresponding to the radius of curvature of the distal end 31a of the discharge electrode 31, which has been determined at step S2 based on the relationship shown in Fig. 11 between the radius of curvature of the distal end 31a of the discharge electrode 31 and the ozone concentration in the indoor unit. By way of example, an ozone concentration Cuni03X in the indoor unit corresponding to the radius of curvature rx of the distal end 31a of the discharge electrode 31 is determined, thereby rendering a current ozone concentration to become known.

[0155] At step S4, the controller 9 determines a running rate of the electric discharge portion 33 of the purification unit 8 during the purification operation based on the ozone concentration in the indoor unit determined at step S3.

[0156] The controller 9 controls the high-voltage generating device 34 to control electric discharge of the electric discharge portion 33. Specifically, when the purification unit 8 purifies the interior of the main body 1 of the indoor unit (during the purification operation), the controller 9 alternately repeats starting and stopping (turning on and off) the electric discharge of the electric discharge portion 33 through the high-voltage generating device 34. The running rate is an ON-time per unit time and, for example, a duty ratio.

[0157] Specifically, the running rate of the electric discharge portion 33 is reduced with an increase in ozone concentration in the indoor unit determined at step S3. By way of example, if the current ozone concentration Cuni03x increases a -fold compared with the initial ozone concentration Cunio3o, the running rate is reduced a times from an initial running rate.

[0158] Running rate = Initial running rate x (Cunio3o/Cunio3x). The running rate is determined using the above formula. Based on this formula, the amount of ozone generated by the purification unit 8 is maintained constant. However, if the rate of ozone generation at the time of electric discharge varies depending on a value of the running rate, it is preferred that the running rate be corrected.

[0159] In the practice of the present invention, the running rate is not limited to maintaining the amount of ozone generation constant. It is sufficient at least if the running rate is determined so as to be able to restrain deterioration of the component parts within the indoor unit, not to emit ozone odor in the vicinity of the indoor unit, and to generate an amount of ozone within a predetermined range that can sufficiently sterilize the interior of the main body 1 of the indoor unit. Because the amount of ozone within the predetermined range depends greatly on the size of the electric discharge portion 33, the applied voltage, the size and construction of the indoor unit, and the like, it is determined by actually confirming ozone odor and the degree of deterioration of the component parts.

[0160] At step S5, the controller 9 controls the electric discharge of the electric discharge portion 33 through the high-voltage generating device 34 using the running rate determined at step S4. Specifically, the controller 9 controls the high-voltage generating device 34 to intermittently and periodically apply a voltage to the high-voltage generating device 34 based on the running rate. The intermittent period for voltage application preferably ranges from several seconds to several tens of minutes.

[0161] In the flow of Fig. 12, the control to be executed at step S2 may be omitted. As shown in Fig. 9, the value of integral of the discharge current calculated at step S1 corresponds unambiguously to the radius of curvature of the distal end 31a of the discharge electrode 31, which in turn corresponds unambiguously to the ozone concentration determined at step S3, as shown in Fig. 10. For this reason, the value of integral of the discharge current corresponds unambiguously to the ozone concentration. Accordingly, the ozone concentration can be determined based on the correspondence relationship between the value of integral of the discharge current obtained experimentally in advance and the ozone concentration and on the value of integral of the discharge current calculated at step S1.

[0162] As described above, even if the radius of curvature of the distal end 31a of the discharge electrode 31 changes over time, an amount of ozone within the predetermined range can be generated by controlling the electric discharge for ozone generation based on the radius of curvature of the distal end 31a of the discharge electrode 31, thereby making it possible to restrain deterioration of the component parts within the indoor unit that may be caused by ozone. Also, in controlling the amount of ozone within the predetermined range, the control of the electric discharge portion 33 with the use of the running rate is less expensive than the control of the voltage applied to the electric discharge portion 33 (in controlling the applied voltage, the high-voltage generating device 34 must have variable output voltage values).

[0163] (Embodiment 6) A sixth embodiment differs from the fifth embodiment in that in the former the radius of curvature of the distal end 31a of the discharge electrode 31 is determined using a cumulative discharge time and the ozone concentration in the indoor unit is controlled by controlling the discharge time.

[0164] An air conditioner according to the sixth embodiment is next explained. The same component parts as those in the above-described embodiments are designated by the same signs and explanation thereof is omitted.

[0165] Fig. 13 depicts a relationship between the cumulative discharge time (total discharge time) of the electric discharge portion 33 and the radius of curvature of the distal end 31a of the discharge electrode 31. In a graph of Fig. 13, a horizontal axis indicates the cumulative discharge time and a vertical axis indicates the radius of curvature of the distal end 31 a of the discharge electrode 31.

[0166] As shown in Fig. 13, the radius of curvature of the distal end 31a of the discharge electrode 31 increases monotonically with an increase in cumulative discharge time. It can be seen that the relationship shown in Fig. 13 between the cumulative discharge time and the radius of curvature of the distal end 31a of the discharge electrode 31 is nearly analogous to the relationship shown in Fig. 9 between the value of integral of the discharge current and the radius of curvature of the distal end 31a of the discharge electrode 31. Accordingly, the radius of curvature of the distal end 31a of the discharge electrode 31 can be determined based on the cumulative discharge time.

[0167] The reason for this can be understood from a relationship shown in Fig. 14 between the cumulative discharge time and the discharge current. As shown in Fig. 14, the discharge current (vertical axis) reduces monotonically with an increase in cumulative discharge time (horizontal axis). Because the discharge current corresponds unambiguously to the cumulative discharge time, the value of integral of the discharge current also corresponds unambiguously to the cumulative discharge time. Accordingly, the radius of curvature of the distal end 31a of the discharge electrode 31 can be determined from the cumulative discharge time using the relationship shown in Fig. 13 in place of the value of integral of the discharge current.

[0168] A control of the electric discharge portion 33 according to the sixth embodiment is explained hereinafter with reference to Fig. 15. A flow shown in Fig. 15 indicates a control to be executed during the purification operation.

[0169] At step S11, the controller 9 calculates the cumulative discharge time.The cumulative discharge time can be calculated, for example, by detecting the presence or absence of the discharge current at regular intervals and integrating a time period during which the discharge current flows. It is preferred in terms of an enhanced accuracy that each interval for periodic detection of the discharge current be less than a hundredth of a time period from when the discharge current begins to flow till when it stops flowing.

[0170] At step S12, the controller 9 determines the radius of curvature of the distal end 31a of the discharge electrode 31 based on the relationship shown in Fig. 13 between the cumulative discharge time and the radius of curvature of the distal end 31a of the discharge electrode 31 and on the cumulative discharge time calculated at step S11. If the cumulative discharge time is tx, a radius of curvature rx corresponding thereto is determined, thereby rendering a current radius of curvature of the distal end 31a of the discharge electrode 31 to become known.

[0171] At step S13, the controller 9 determines the ozone concentration based on the relationship shown in Fig. 11 between the radius of curvature of the distal end 31a of the discharge electrode 31 and the ozone concentration in the indoor unit and on the radius of curvature determined at step S12, thereby rendering a current ozone concentration in the indoor unit to become known.

[0172] At step S14, the controller 9 determines a duration of the purification operation (purification operation time) based on the ozone concentration in the indoor unit determined at step S13. Specifically, the discharge time of the electric discharge portion 33 is reduced with an increase in ozone concentration in the indoor unit. By way of example, if the ozone concentration Cunio3x in the indoor unit increases a -fold compared with the initial ozone concentration Cunio3o. the discharge time is reduced a times from an initial discharge time.

[0173] Purification operation time = Initial purification operation time x (Cunio3o/Cuni03x)
The purification operation time is determined using the above formula. Based on this formula, the amount of ozone generated by the purification unit 8 is maintained constant. However, if the rate of ozone generation at the time of electric discharge varies depending on a value of the purification operation time, it is preferred that the purification operation time be corrected.

[0174] In the practice of the present invention, the purification operation time is not limited to maintaining the amount of ozone generation constant. It is sufficient at least if the purification operation time is determined so as to be able to restrain deterioration of the component parts within the indoor unit, not to emit ozone odor in the vicinity of the indoor unit, and to generate an amount of ozone within a predetermined range that can sufficiently sterilize the interior of the main body 1 of the indoor unit.

[0175] Finally, at step S15, the controller 9 controls the electric discharge portion 33 to continue discharging (continue generating ozone) for the purification operation time determined at step S14.

[0176] Although a time period (purification operation time) is used for control of the electric discharge portion 33, a combination of the time period and the running rate may be used. Also, the value of integral of the discharge current may be used to determine the radius of curvature of the distal end 31a of the discharge electrode 31 and the time period may be used to control the electric discharge portion 33. Alternatively, the cumulative discharge time may be used to determine the radius of curvature of the distal end 31a of the discharge electrode 31 and the running rate may be used to control the electric discharge portion 33.

[0177] As described above, as in the fifth embodiment, even if the radius of curvature of the distal end 31a of the discharge electrode 31 changes over time, an amount of ozone within the predetermined range can be generated by controlling electric discharge for ozone generation based on the radius of curvature of the distal end 31a of the discharge electrode 31, thereby making it possible to further restrain deterioration of the component parts within the indoor unit that may be caused by ozone. Also, the radius of curvature of the distal end 31a of the discharge electrode 31 can be easily determined using the cumulative discharge time and not the value of integral of the discharge current.

[0178] (Embodiment 7) A seventh embodiment is an improved form of the fifth and sixth embodiments. The seventh embodiment differs from the fifth and sixth embodiments in that in the former the electric discharge of the electric discharge portion 33 is brought to a stop when the radius of curvature of the distal end 31a of the discharge electrode 31 has reached a critical radius of curvature (critical radius of curvature of the distal end).

[0179] An air conditioner according to the seventh embodiment is next explained. The same component parts as those in the above-described embodiments are designated by the same signs and explanation thereof is omitted.

[0180] Fig. 16 depicts a control flow of the purification unit 8 to be executed by a controller 9 according to the seventh embodiment. The control flow of the purification unit 8 shown in Fig. 16 is analogous to the control flow of the purification unit 8 according to the sixth embodiment shown in Fig. 15 and, hence, only different portions are explained in detail.

[0181] As shown in Fig. 16, as with step S11 in the sixth embodiment of Fig. 15, the controller 9 calculates the cumulative discharge time at step 21.

[0182] At step S22, as with step S12 in the sixth embodiment of Fig. 15, the controller 9 determines the radius of curvature of the distal end 31a of the discharge electrode 31 based on the cumulative discharge time calculated at step S21.

[0183] At step S23, the controller 9 determines as to whether or not the radius of curvature of the distal end 31a of the discharge electrode 31 determined at step S22 is greater than the critical radius of curvature of the distal end.

[0184] The term "the critical radius of curvature of the distal end" as used herein is a radius of curvature of the distal end 31a of the discharge electrode 31 that has been derived from, for example, experiments in advance, can generate an amount of ozone that may cause serious deterioration of the component parts within the indoor unit, and differs depending on an internal construction of the indoor unit. Accordingly, if the purification operation is conducted under conditions in which the radius of curvature of the distal end 31a of the discharge electrode 31 has exceeded the critical radius of curvature of the distal end, it is likely that the component parts within the indoor unit may be seriously deteriorated.

[0185] If the radius of curvature rx of the distal end 31a of the discharge electrode 31 determined at step S22 is less than the critical radius of curvature riimi, of the distal end (in the case of NO), the program advances to step S24. If not (in the case of YES), the program advances to step S27.

[0186] As with step S13 in the sixth embodiment of Fig. 15, at step S24, the controller 9 determines the ozone concentration in the indoor unit based on the radius of curvature of the distal end 31a of the discharge electrode 31 determined at step S22.

[0187] As with step S14 in the sixth embodiment of Fig. 15, at step S25, the controller 9 determines the purification operation time based on the ozone concentration determined at step S24. At step S26, the controller 9 controls the electric discharge portion 33 based on the purification operation time determined at step S24.

[0188] On the other hand, if a determination is made at step S23 that the radius of curvature rx of the distal end 31a of the discharge electrode 31 is greater than the critical radius of curvature rijmit of the distal end, the controller 9 determines the purification operation time to be zero at step S27, followed by step S26, at which the controller 9 controls the electric discharge portion 33 based on the zero-purification operation time. That is, the electric discharge portion 33 stops discharging electricity or the purification operation is suspended or not started.

[0189] As described above, based on the radius of curvature of the distal end 31a of the discharge electrode 31, ozone can be restrained from being generated in an amount that causes serious deterioration of the component parts within the indoor unit, thus making it possible to restrain failure from arising in the indoor unit of the air conditioner.

[0190] Fig. 17 depicts a control flow of the purification unit 8 to be executed by a controller 9 according to an improved form of the seventh embodiment. The control flow of the purification unit 8 shown in Fig. 17 is analogous to the control flow of the purification unit 8 shown in Fig. 16 and, hence, only different portions are explained.

[0191] As with step S4 in the fifth embodiment of Fig. 12, at step S25' following step S24 in Fig. 17, the controller 9 determines the running rate of the electric discharge portion 33 based on the radius of curvature of the distal end 31a of the discharge electrode 31 determined at step S24. At step S26', the controller 9 controls the electric discharge portion 33 based on the running rate determined at step S25'.

[0192] On the other hand, if a determination is made at step S23 in Fig. 17 that the radius of curvature rx of the distal end 31a of the discharge electrode 31 is greater than the critical radius of curvature rimm of the distal end, the controller 9 determines the running rate of the electric discharge portion 33 to be zero at step S27', followed by step S26', at which the controller 9 controls the electric discharge portion 33 based on the zero-running rate. That is, the electric discharge portion 33 stops discharging electricity or the purification operation is suspended or not started.

[0193] Also in this improved form, based on the radius of curvature of the distal end 31a of the discharge electrode 31, ozone can be restrained from being generated in an amount that causes serious deterioration of the component parts within the indoor unit, thus making it possible to restrain failure from arising in the indoor unit of the air conditioner.

[0194] Further, when the value of integral of the discharge current has reached a critical value of integral of the discharge current, the electric discharge portion 33 may be brought into a stop.

[0195] The term "a critical value of integral of the discharge current" as used herein is a value of integral of the discharge current corresponding to "the critical radius of curvature of the distal end". As shown in Fig. 9, if the value of integral of the discharge current is determined, the radius of curvature of the distal end 31a of the discharge electrode 31 is unambiguously determined. Accordingly, there exists a critical value of integral Q|imit of the discharge current corresponding to the critical radius of curvature rumit of the distal end. The critical value of integral of the discharge current is derived from, for example, experiments in advance and differs depending on an internal construction of the indoor unit.

[0196] Fig. 18 depicts a control flow of the purification unit 8 that is executed by a controller 9 according to an improved form of the seventh embodiment using a critical value of integral of the discharge current. The control flow of the purification unit 8 shown in Fig. 18 is analogous to the control flow of the purification unit 8 in the fifth embodiment shown in Fig. 12 and, hence, only different portions are explained in detail.

[0197] As shown in Fig. 18, as with step S1 in the fifth embodiment of Fig. 12, the controller 9 calculates a value of integral of the discharge current at step S31.

[0198] At step S32, the controller 9 determines as to whether or not the value of integral Qx of the discharge current calculated at step S31 is greater than the critical value of integral Q|imit of the discharge current. If the value of integral Qx of the discharge current is less than the critical value of integral OW of the discharge current (in the case of NO), the program advances to step S33. If not (in the case of YES), the program advances to step S37.

[0199] As with step S2 in the fifth embodiment of Fig. 12, at step S33, the controller 9 determines the radius of curvature of the distal end 31a of the discharge electrode 31 based on the value of integral of the discharge current calculated at step S31.

[0200] As with step S3 in the fifth embodiment of Fig. 12, at step S34, the controller 9 determines the ozone concentration in the indoor unit based on the radius of curvature of the distal end 31a of the discharge electrode 31 determined at step S33.

[0201] As with step S4 in the fifth embodiment of Fig. 12, at step S35, the controller 9 determines the running rate of the electric discharge portion 33 based on the ozone concentration in the indoor unit determined at step S34. At step S36, the controller 9 controls the electric discharge portion 33 based on the running rate determined at step S35.

[0202] On the other hand, if a determination is made at step S32 that the value of integral Qx of the discharge current is greater than the critical value of integral Qumit of the discharge current, the controller 9 determines the running rate of the electric discharge portion 33 to be zero at step S37, followed by step S36, at which the controller 9 controls the electric discharge portion 33 based on the zero-running rate. That is, the electric discharge portion 33 stops discharging electricity or the purification operation is suspended or not started.

[0203] The purification unit 8 may be provided with a fuse that melts if the discharge current flows and the value of integral thereof reaches a predetermined critical value of integral of the discharge current. If the fuse melts, the running rate of the electric discharge portion 33 becomes zero. That is, current supply to the electric discharge portion 33 is suspended to thereby stop discharging electricity. Because the electric discharge of the electric discharge portion is mechanically stopped by the fuse, the reliability of the purification unit 8 (that is, air conditioner) is high compared with a case where upon detection of the predetermined critical value of integral of the discharge current, the electric discharge portion 33 is controlled to stop discharging electricity. Also, if the purification unit 8 is designed such that the electric discharge of the electric discharge portion 33 is stopped mechanically by the fuse and, at the same time, the electric discharge portion 33 is controlled to stop discharging electricity, the reliability is further enhanced.

[0204] As described above, ozone can be restrained from being generated in an amount that causes serious deterioration of the component parts within the indoor unit by stopping the electric discharge of the electric discharge portion 33 when the radius of curvature of the distal end 31a of the discharge electrode 31 has exceeded the critical radius of curvature of the distal end or the value of integral of the discharge current has exceeded the critical value of integral of the discharge current, thus making it possible to restrain failure from arising in the indoor unit of the air conditioner.

[0205] Although the present invention has been explained with a plurality of embodiments, the present invention is not limited to these embodiments.

[0206] By way of example, of the plurality of embodiments referred to above, any combination thereof is also possible.

[0207] Also, although in the above-described embodiments the air conditioner is provided with a heat exchanger, the present invention is applicable to an air conditioner with no heat exchanger, i.e., an air cleaner or purifier.

[0208] Although the present invention has been fully described by way of preferred embodiments with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications otherwise depart from the scope of the present invention as set forth in the appended claims, they should be construed as being included therein.

[0209] The contents of a specification, drawings and claims of a Japanese patent application No. 2011 -134885 filed June 17, 2011, those of a Japanese patent application No. 2012-033720 filed February 20, 2012, and those of a Japanese patent application No. 2012-033724 filed February 20, 2012 are herein expressly incorporated by reference in their entirety.

Industrial Applicability

[0210] As described above, in the air conditioner according to the present invention, after the interior of the indoor unit has been purified by ozone generated by the purification unit, the fan is operated to effectively discharge ozone remaining in the indoor unit outside. By doing so, deterioration of the component parts within the indoor unit that may be caused by ozone can be restrained. Accordingly, the present invention is applicable to any air conditioners having a fan and a purification unit for home use or business use.

Explanation of reference numerals

[0211]
1 main body
2 suction opening
3 discharge opening
4 air filter
5 fan
6 heat exchanger
7 louver
8 purification unit
9 controller
10 suction air temperature detecting means
11 operation switching means
12 compressor
13 heat exchanger temperature detecting means

CLAIMS

1. An air conditioner comprising:
an indoor unit; a fan accommodated in the indoor unit; and a purification unit accommodated in the indoor unit to generate at least ozone by means of electric discharge for purification of an interior of the indoor unit; wherein after an air conditioning operation has been brought to a stop, the purification unit is operated to purify the interior of the indoor unit for a predetermined time period, and after the purification unit has been brought to a stop, the fan is operated to discharge ozone within the indoor unit outside.

2. The air conditioner according to claim 1, further comprising a suction air temperature detecting means operable to detect a temperature of air inhaled into the indoor unit from within a room, wherein an operating time period of the fan after purification, which indicates the operating time period of the fan after stop of operation of the purification unit, is determined based on a temperature detected by the suction air temperature detecting means.

3. The air conditioner according to claim 1 or 2, wherein the operating time period of the fan after purification is determined based on an air conditioning operation mode before start of operation of the purification unit.

4. The air conditioner according to any one of claims 1 to 3, further comprising a louver operable to open and close a discharge opening defined in the indoor unit, through which air within the indoor unit is discharged outside, wherein the purification unit is operated with the discharge opening closed by the louver and the fan is subsequently operated with the discharge opening opened at least
partially by the louver.

5. The air conditioner according to any one of claims 1 to 4, wherein after stop of operation of the purification unit, a heating operation is conducted and the fan is operated.

6. The air conditioner according to any one of claims 1 to 5, wherein after stop of a cooling operation, the fan is operated to dry the interior of the indoor unit and after stop of operation of the fan, operation of the purification unit is started to purify the interior of the indoor unit.

7. The air conditioner according to claim 6, further comprising a heat exchanger accommodated in the indoor unit, a suction air temperature detecting means operable to detect a temperature of air inhaled into the indoor unit from within a room, and a heat exchanger temperature detecting means operable to detect a temperature of the heat exchanger, wherein an operating time period of the fan before purification, which indicates the operating time period of the fan after stop of the cooling operation and before start of purification by the purification unit, is determined based on a temperature detected by the suction air temperature detecting means and a temperature detected by the heat exchanger temperature detecting means.

8. The air conditioner according to claim 7, further comprising an outdoor temperature detecting means operable to detect an outdoor temperature, wherein the operating time period of the fan before purification is increased or decreased based on a temperature detected by the outdoor temperature detecting means.

9. The air conditioner according to any one of claims 6 to 8, further comprising a louver operable to open and close a discharge opening defined in the indoor unit, through which air within the indoor unit is discharged outside, wherein after stop of the cooling operation of the air conditioner, the fan is operated with the discharge opening opened at least partially by the louver and the purification unit is subsequently operated with the discharge opening closed by the louver.

10. The air conditioner according to any one of claims 1 to 9, wherein the purification unit comprises an electric discharge portion, which comprises a discharge electrode having a sharp distal end to discharge electricity for ozone generation, and a controller operable to control electric discharge of the electric discharge portion to generate an amount of ozone within a predetermined range based on a radius of curvature of the distal end of the discharge electrode.

11. The air conditioner according to claim 10, wherein the radius of curvature of the distal end of the discharge electrode is determined based on a cumulative discharge time of the electric discharge portion.

12. The air conditioner according to claim 10, wherein the radius of curvature of the distal end of the discharge electrode is determined based on a value of integral of a discharge current.

13. The air conditioner according to any one of claims 10 to 12, wherein the controller controls a running rate of the electric discharge portion to maintain an amount of ozone generation within a predetermined range.

14. The air conditioner according to claim 13, wherein the controller controls the running rate of the electric discharge portion to be zero when the radius of curvature of the distal end of the discharge electrode reaches a predetermined critical radius of curvature of the distal end.

15. The air conditioner according to claim 14, further comprising a fuse that melts when a discharge current flows through the electric discharge portion and a value of integral thereof reaches a predetermined critical value of integral of the discharge current, wherein when the fuse melts, the running rate of the electric discharge portion becomes zero.

16. The air conditioner according to any one of claims 10 to 12, wherein the controller controls a discharge time of the electric discharge portion to maintain an amount of ozone generation within a predetermined range.

17. The air conditioner according to claim 16, wherein the controller controls the discharge time of the electric discharge portion to be zero when the radius of curvature of the distal end of the discharge electrode reaches a predetermined critical radius of curvature of the distal end.

18. The air conditioner according to any one of claims 10 to 17, wherein a dust-collecting operation is conducted to discharge ions generated by the electric discharge portion to the interior of the room.

19. The air conditioner according to claim 18, wherein the electric discharge portion is located in an air passageway or adjacent thereto.

20. The air conditioner according to claim 19, wherein the electric discharge portion comprises a discharge electrode having a distal end, to which a negative potential is applied, and an opposite electrode confronting the distal end of the discharge electrode, a positive potential being applied to the opposite electrode, and wherein the opposite electrode is positioned on an air passageway side relative to the discharge electrode to allow an ionic wind generated by the electric discharge portion to flow within the indoor unit through the air passageway.