JP7845273B2 - air conditioner - Google Patents

Description

This invention relates to an air conditioner that performs moist heat sterilization.

Patent Document 1 discloses an air conditioner. The air conditioner performs an internal cleaning operation after cooling operation. In the internal cleaning operation, heating operation is performed after fan operation. A strong airflow setting is applied at the start of fan operation. The strong airflow blows away moisture present inside the indoor unit. Moisture inside the indoor unit is removed during heating operation. As disclosed in Patent Document 2, an air conditioner is proposed that achieves moist heat sterilization by utilizing condensation water generated on the surface of the heat exchanger.

Japanese Patent Publication No. 2009-299983 Patent No. 6399181

In the moist heat sterilization method disclosed in Patent Document 2, a heating cycle operation is performed following a fan operation. Here, "heating cycle operation" refers to an operation other than so-called heating operation that establishes refrigerant circulation similar to that during heating operation. However, if moisture inside the indoor unit is removed during the heating cycle operation, as in Patent Document 1, sufficient moist heat sterilization cannot be achieved. On the other hand, if too much moisture remains after the heating cycle operation, the humidity inside the indoor unit increases, inducing mold growth.

The present invention aims to provide an air conditioner that can achieve moist heat sterilization and effectively suppress mold growth.

According to a first aspect of the present invention, an air conditioner is provided comprising: an indoor unit that generates an airflow passing through a heat exchanger in accordance with the rotation of a blower fan and blows out the airflow from an outlet; an outdoor unit that supplies a refrigerant to the heat exchanger in accordance with the operation of a compressor and an expansion valve; a heating control unit that performs a heating cycle operation while maintaining condensation water in the gaps of the heat exchanger and maintains the temperature of the heat exchanger at 55 degrees Celsius or higher; and a pre-treatment control unit that, prior to the heating cycle operation, performs a blower operation to remove moisture adhering to the surface of the heat exchanger while leaving condensation water on the heat exchanger so as to maintain the condensation water in the gaps of the heat exchanger during the heating cycle operation.

During the heating cycle, condensation is maintained, and if the heat exchanger temperature is maintained above 55 degrees Celsius, moist heat sterilization is achieved. Mold and bacteria can be effectively sterilized in the condensation. The fan operation dries the surface of the heat exchanger, so the humidity inside the indoor unit can be sufficiently reduced after the heating cycle. Mold growth can be suppressed. Furthermore, since the fan operation is performed prior to the heating cycle, the rise in humidity of the blown airflow at the start of the heating cycle can be suppressed. As a result, occupants do not have to be exposed to humid, warm air. The comfort level of occupants can be maintained. On the other hand, if the fan operation is excessively prolonged, condensation will evaporate from the gaps in the heat exchanger, and sufficient sterilization will not be achieved during the heating cycle. Conversely, if the surface of the heat exchanger is not sufficiently dried during the fan operation, the humidity of the blown airflow will rise significantly at the start of the heating cycle, worsening the comfort level of occupants.

The air conditioner may include a post-treatment control unit that performs a fan operation after the heating cycle to evaporate any condensation remaining in the gaps. This dries the inside of the indoor unit, thereby suppressing (preventing) mold growth.

The temperature of the heat exchanger should be maintained below a limit temperature determined in accordance with the upper limit temperature of the compressor's operating temperature range. The compressor has an operating temperature range that guarantees its operation. When the compressor temperature is maintained below the upper limit temperature of the operating temperature range, the compressor's operation can be reliably ensured. If the compressor's operation is suppressed during heating operation, a rise in the compressor's temperature can be avoided. In this air conditioner, the temperature of the heat exchanger is used for compressor temperature control. If the heat exchanger temperature exceeds the limit temperature, the compressor's operation is suppressed (for example, the compressor stops). Therefore, if the heat exchanger temperature is kept below the limit temperature, the compressor's operation is not suppressed, and the heating of the heat exchanger can be maintained well. In addition, since the heat exchanger is not heated to a temperature exceeding the limit temperature, excessively warm airflow from the indoor unit into the room can be prevented. This prevents deterioration of the indoor living environment.

The pre-processing control unit may have a reference table that defines the rotational speed per minute and the blowing time of the blower fan for the blowing operation, each using a single fixed value. Condensation droplets gradually grow on the surface of the heat exchanger and flow down the surface due to gravity. Therefore, the rotational speed per minute and blowing time of the blower can be determined based on the amount of moisture expected to remain on the heat exchanger surface against gravity.

According to a second aspect of the present invention, an air conditioner is provided comprising: an indoor unit that generates an airflow passing through a heat exchanger in accordance with the rotation of a blower fan and blows out the airflow from an outlet; an outdoor unit that supplies a refrigerant to the heat exchanger in accordance with the operation of a compressor and an expansion valve; a heating control unit that performs a heating cycle operation and maintains the temperature of the heat exchanger at 55 degrees Celsius or higher for a predetermined duration; and a pre-treatment control unit that performs a fan operation prior to the heating cycle operation, and in the fan operation, determines the rotation speed of the blower fan according to the amount of condensation water generated on the heat exchanger during the cooling operation prior to the heating cycle operation, so as to maintain condensation water on the heat exchanger during the duration of the heating cycle operation, and drives the blower fan at the determined rotation speed.

During continuous heating cycle operation, condensation is maintained, and if the heat exchanger temperature is maintained above 55 degrees Celsius, moist heat sterilization is achieved. Mold and bacteria can be effectively sterilized in the condensation. Fan operation dries the surface of the heat exchanger, allowing the humidity inside the indoor unit to decrease sufficiently after the heating cycle. Mold growth can be suppressed. Furthermore, since the fan speed is determined according to the amount of condensation during fan operation, the optimal humidity level for maintaining condensation can be established on the heat exchanger. Therefore, the fan operation time can be shortened. If fan operation is excessively prolonged, the condensation will evaporate from the heat exchanger, and sufficient sterilization will not be achieved during the heating cycle. Conversely, if the surface of the heat exchanger is not sufficiently dried during fan operation, the humidity of the blown airflow will increase significantly at the start of the heating cycle, worsening the skin comfort of occupants.

The pre-processing control unit may determine the rotation speed of the blower fan based on the operating time of the cooling operation. Since the amount of condensation generated in the heat exchanger depends on the operating time of the cooling operation, if the rotation speed of the blower fan during the blower operation is determined according to the operating time of the cooling operation, an optimal level of humidity can be established in the heat exchanger at the end of the blower operation.

The air conditioner may further include a humidity sensor located inside the indoor unit to measure the humidity inside the indoor unit. In this case, the pre-processing control unit may determine the rotation speed of the blower fan based on the humidity detected by the humidity sensor. Since the amount of condensation generated in the heat exchanger depends on the humidity inside the indoor unit, if the rotation speed of the blower fan during operation is determined according to the humidity sensor's measurement, an optimal humidity level can be established in the heat exchanger at the end of the operation.

As described above, the disclosed air conditioner can achieve moist heat sterilization and effectively suppress mold growth.

This is a conceptual diagram illustrating the configuration of an air conditioner according to one embodiment of the present invention. This is a schematic perspective view showing the appearance of an indoor unit according to one embodiment. This is a perspective view showing a schematic representation of the indoor unit's main body. This is an exploded perspective view showing a schematic representation of the indoor unit's structure. This is an enlarged vertical cross-sectional view of the indoor unit's main body. This is a block diagram that schematically shows the configuration of the control unit. This is an enlarged plan view that schematically shows the appearance and display of the remote control. This is a flowchart that outlines the heat sterilization process. This graph shows the time-dependent change in the rate of humidity change per minute.

The following describes one embodiment of the present invention with reference to the attached drawings.

(1) Configuration of the air conditioner Figure 1 schematically shows the configuration of an air conditioner 11 according to one embodiment of the present invention. The air conditioner 11 comprises an indoor unit 12 and an outdoor unit 13. The indoor unit 12 is installed, for example, in an indoor space within a building. Otherwise, the indoor unit 12 may be installed in any space equivalent to an indoor space. An indoor heat exchanger 14 is incorporated into the indoor unit 12. The outdoor unit 13 incorporates a compressor 15, an outdoor heat exchanger 16, an expansion valve 17, and a four-way valve 18. The indoor heat exchanger 14, compressor 15, outdoor heat exchanger 16, expansion valve 17, and four-way valve 18 form a refrigeration circuit 19. The outdoor unit 13 may be installed outdoors where heat exchange with the outdoor air is possible.

The refrigeration circuit 19 includes a first circulation path 21. The first circulation path 21 connects the first port 18a and the second port 18b of the four-way valve 18. A compressor 15 is provided in the first circulation path 21. The suction pipe 15a of the compressor 15 is connected to the first port 18a of the four-way valve 18 via refrigerant piping. Gas refrigerant is supplied from the first port 18a to the suction pipe 15a of the compressor 15. The compressor 15 compresses the low-pressure gas refrigerant to a predetermined pressure. The discharge pipe 15b of the compressor 15 is connected to the second port 18b of the four-way valve 18 via refrigerant piping. Gas refrigerant is supplied from the discharge pipe 15b of the compressor 15 to the second port 18b of the four-way valve 18. The refrigerant piping can be, for example, copper pipe.

The refrigeration circuit 19 further includes a second circulation path 22. The second circulation path 22 connects the third port 18c and the fourth port 18d of the four-way valve 18. The second circulation path 22 incorporates, in order from the third port 18c side, an outdoor heat exchanger 16, an expansion valve 17, and an indoor heat exchanger 14. The outdoor heat exchanger 16 exchanges thermal energy between the refrigerant passing through it and the air in contact with it. The indoor heat exchanger 14 exchanges thermal energy between the refrigerant passing through it and the air in contact with it.

The outdoor unit 13 incorporates a blower fan 23. The blower fan 23 provides airflow to the outdoor heat exchanger 16. The blower fan 23 generates airflow, for example, according to the rotation of its impeller. The airflow, mediated by the blower fan 23, passes through the outdoor heat exchanger 16. Outdoor air passes through the outdoor heat exchanger 16 and exchanges heat with the refrigerant. The resulting cool or warm air is then blown out from the outdoor unit 13. The airflow rate is adjusted according to the rotation speed of the impeller.

The indoor unit 12 incorporates a blower fan 24. The blower fan 24 provides airflow to the indoor heat exchanger 14. The blower fan 24 generates airflow according to the rotation of its impeller. The blower fan 24 draws indoor air into the indoor unit 12. The indoor air passes through the indoor heat exchanger 14 and exchanges heat with the refrigerant. The resulting cool or warm air is then blown out from the indoor unit 12. The airflow rate is adjusted according to the rotation speed of the impeller.

The indoor unit 12 is equipped with upper and lower air deflectors 25a and 25b. These deflectors define the direction of the airflow blown out from the indoor unit 12. Details of the structure of the upper and lower air deflectors 25a and 25b will be described later.

When cooling operation is performed in the refrigeration circuit 19, the four-way valve 18 connects the second port 18b and the third port 18c, and connects the first port 18a and the fourth port 18d. Therefore, high-temperature, high-pressure refrigerant is supplied from the discharge pipe 15b of the compressor 15 to the outdoor heat exchanger 16. The refrigerant flows sequentially through the outdoor heat exchanger 16, the expansion valve 17, and the indoor heat exchanger 14. In the outdoor heat exchanger 16, heat is released from the refrigerant to the outside air. In the expansion valve 17, the refrigerant is reduced to a low pressure. The reduced-pressure refrigerant absorbs heat from the surrounding air in the indoor heat exchanger 14. Cold air is generated. The cold air is blown into the indoor space by the action of the blower fan 24.

When heating operation is performed in the refrigeration circuit 19, the four-way valve 18 connects the second port 18b and the fourth port 18d, and connects the first port 18a and the third port 18c. High-temperature, high-pressure refrigerant is supplied from the compressor 15 to the indoor heat exchanger 14. The refrigerant flows sequentially through the indoor heat exchanger 14, the expansion valve 17, and the outdoor heat exchanger 16. In the indoor heat exchanger 14, the refrigerant releases heat into the surrounding air, generating warm air. This warm air is blown into the indoor space by the action of the blower fan 24. The refrigerant is reduced to a low pressure in the expansion valve 17. The reduced-pressure refrigerant absorbs heat from the surrounding air in the outdoor heat exchanger 16. After that, the refrigerant returns to the compressor 15.

The air conditioner 11 is equipped with a temperature sensor 26a and a humidity sensor 26b. The temperature sensor 26a is attached to the indoor heat exchanger 14. The temperature sensor 26a measures the temperature of the indoor heat exchanger 14. The temperature sensor 26a outputs a temperature signal containing the measured temperature information. The humidity sensor 26b is located inside the indoor unit 12. The humidity sensor 26b measures the relative humidity inside the indoor unit 12. The humidity sensor 26b outputs a humidity signal containing the measured humidity information.

The air conditioner 11 includes a control unit 27. The control unit 27 is formed on a control board (not shown) incorporated into the outdoor unit 13, for example. The control unit 27 is electrically connected to the four-way valve 18, expansion valve 17, and compressor 15 in the outdoor unit 13 via separate signal lines. Similarly, the control unit 27 is electrically connected to the drive motor of the blower fan 24, the drive sources for the upper and lower air deflectors 25a and 25b, the temperature sensor 26a, and the humidity sensor 26b in the indoor unit 12 via separate signal lines. Based on the temperature signal from the temperature sensor 26a and the humidity signal from the humidity sensor 26b, the control unit 27 controls the operation of the four-way valve 18, expansion valve 17, blower fan 23, and compressor 15 in the outdoor unit 13, as well as the blower fan 24 in the indoor unit 12. As a result of this control, the air conditioner 11 performs cooling, heating, and heat sterilization operations, as described later.

(2) Configuration of the indoor unit Figure 2 schematically shows the appearance of an indoor unit 12 according to one embodiment. An outer panel 28b covers the main body (casing) 28a of the indoor unit 12. An air outlet 29 is formed on the lower surface of the main body 28a. The air outlet 29 opens towards the room. The main body 28a can be fixed to, for example, the wall surface of the room. Cold air or warm air is generated in the indoor heat exchanger 14, and the airflow of cold air or warm air is blown out from the air outlet 29.

The air outlet 29 is equipped with a pair of upper and lower air deflectors 25a and 25b. Each of the upper and lower air deflectors 25a and 25b can rotate around a rotation axis 32a and 32b, parallel to the longitudinal direction of the main body. The upper and lower air deflectors 25a and 25b open and close the air outlet 29 in accordance with their rotation. The direction of the airflow can be changed depending on the angle of the upper and lower air deflectors 25a and 25b.

As shown in Figure 3, an intake port 33 is formed in the main body 28a. The intake port 33 opens on the front and top surfaces of the main body 28a. Indoor air is drawn into the main body 28a through the intake port 33 and supplied towards the indoor heat exchanger 14.

An air filter assembly 34 is arranged in the intake port 33 in a direction parallel to the rotation axes 32a and 32b. The air filter assembly 34 comprises an air filter 35 and a dust box 36. The air filter 35 is held in the dust box 36. The dust box 36 is detachably attached to the main body 28a. When the dust box 36 is set on the main body 28a, the air filter 35 is positioned across the entire surface of the intake port 33.

The dust box 36 has a front filter rail 38. The main body 28a has a rear filter rail 39 that corresponds to the extension of the front filter rail 38. The filter rails 38 and 39 extend along vertical planes perpendicular to the rotation axes 32a and 32b. The left and right ends of the air filter 35 are slidably held by the filter rails 38 and 39. The air filter 35 is driven by a second driven gear 52 (described later) and moves along the filter rails 38 and 39.

As shown in Figure 4, a blower fan 24 is rotatably supported on the main body 28a. For example, a cross-flow fan is used for the blower fan 24. The blower fan 24 rotates around a rotation axis 41 parallel to the rotation axes 32a and 32b. The rotation axis 41 of the blower fan 24 extends horizontally when the main body 28a is installed. The blower fan 24 is positioned parallel to the outlet 29. Driving force is transmitted to the blower fan 24 around the rotation axis 41 from a drive source (not shown). The drive source is supported by the main body 28a. As the blower fan 24 rotates, the airflow passes through the indoor heat exchanger 14. As a result, a flow of cool or warm air is generated. The cool or warm airflow is blown out from the outlet 29.

The indoor heat exchanger 14 comprises a front body 14a and a rear body 14b. The front body 14a faces the blower fan 24 from the front side. The rear body 14b faces the blower fan 24 from the rear side. The front body 14a and the rear body 14b are connected to each other at their upper ends, as will be described later. The front body 14a and the rear body 14b have refrigerant pipes 42a. That is, the refrigerant pipes 42a extend parallel to the rotation axes 32a and 32b, are folded back at the left and right ends of the main body 28a in a front view, extend again parallel to the rotation axes 32a and 32b, are folded back again at the left and right ends of the main body 28a in a front view, and this is repeated. The refrigerant pipes 42a constitute part of the second circulation path 22. Multiple heat dissipation fins 42b are connected to the refrigerant pipes 42a. The heat dissipation fins 42b are arranged parallel to each other while being perpendicular to the rotation axes 32a and 32b. The refrigerant pipes 42a and heat dissipation fins 42b can be made from metallic materials such as copper or aluminum. Heat exchange is achieved between the refrigerant and the air through the refrigerant pipes 42a and heat dissipation fins 42b.

As shown in Figures 4 and 5, the air filter assembly 34 includes a filter cleaning unit 43. The dust box 36 is a component of the filter cleaning unit 43. The dust box 36 comprises an upper dust box 45 and a lower dust box 46. The upper dust box 45 is located on the front side of the air filter 35. The upper dust box 45 has a cover 47. The cover 47 opens and closes the storage space 49 of the box body 48. The lower dust box 46 is located on the rear side of the air filter 35. The upper dust box 45 and the lower dust box 46 sandwich the air filter 35. When cleaning the air filter 35, dust from the front of the air filter 35 is generally collected in the box body 48 of the upper dust box 45, and dust from the rear of the air filter 35 is collected in the lower dust box 46.

The filter cleaning unit 43 includes a first driven gear 51 and a second driven gear 52. The first driven gear 51 is supported by the upper dust box 45. The first driven gear 51 rotates around a horizontal axis 53. The teeth of the first driven gear 51 are partially exposed from the outer surface of the upper dust box 45. Similarly, the second driven gear 52 is supported by the lower dust box 46. The second driven gear 52 rotates around a horizontal axis 54. The second driven gear 52 drives the air filter 35 at both ends of the lower dust box 46. The teeth of the second driven gear 52 are partially exposed from the outer surface of the lower dust box 46. When the air filter assembly 34 is set in the main body 28a, the first driven gear 51 meshes with a first drive gear (not shown) mounted on the main body 28a, and similarly, the second driven gear 52 meshes with a second drive gear (not shown) mounted on the main body 28a. Each drive gear is individually connected to a drive source (not shown), such as an electric motor. The first driven gear 51 and the second driven gear 52 rotate independently according to the driving force supplied by each drive source.

As shown in Figure 5, the filter cleaning unit 43 includes a cleaning brush 56. The cleaning brush 56 is housed in the upper dust box 45. The cleaning brush 56 includes a brush base 57. The brush base 57 can rotate around a horizontal axis 58 by a driving force from the first driven gear 51. The brush bristles 59 are arranged on the cylindrical surface of the brush base 57 over a predetermined central angle range. The bristle placement area of the brush bristles 59 extends across the air filter 35 in the axial direction of the brush base 57. The cleaning brush 56 contacts the air filter 35 with its bristles 59 at a predetermined rotational position, and detaches the bristles 59 from the air filter 35 at other rotational positions. When the air filter 35 moves along a vertical plane perpendicular to the rotational axes 32a and 32b while the brush bristles 59 are in contact with the air filter 35, dust adhering to the front surface of the air filter 35 can be caught by the brush bristles 59.

The filter cleaning unit 43 includes a brush holder 61. The brush holder 61 is housed within the lower dust box 46. The brush holder 61 has a receiving surface 62. The receiving surface 62 faces the cleaning brush 56. When the brush bristles 59 contact the air filter 35, the receiving surface 62 sandwiches the air filter 35 between itself and the brush bristles 59. Additionally, the receiving surface 62 may have brush bristles implanted on it.

The indoor heat exchanger 14 includes a connecting body 63 that connects the front body 14a and the rear body 14b. The connecting body 63 is coupled to the upper ends of the front body 14a and the rear body 14b. The connecting body 63 is formed from a metal material with good thermal conductivity, such as copper or aluminum. The connecting body 63 is formed as a plate that at least partially covers the upper ends of the front body 14a and the rear body 14b. When the blower fan 24 rotates, the air flowing from the intake port 33 toward the blower fan 24 is blocked by the connecting body 63 and does not reach the first region 64 of the indoor heat exchanger 14.

The indoor heat exchanger 14 includes a lower body 14c connected to the lower end of the front body 14a. A windbreak 65, such as a plasma clean unit, is positioned in front of the gap between the front body 14a and the lower body 14c. The windbreak 65 blocks the air flowing from the front of the main body 28a toward the blower fan 24. When the blower fan 24 rotates, the air flowing from the intake port 33 toward the blower fan 24 is blocked by the windbreak 65 and does not reach the second region 66 of the indoor heat exchanger 14.

The indoor unit 12 of the air conditioner 11 is equipped with a drain pan located below the indoor heat exchanger 14. The drain pan includes a first drain pan 67a located below the front body 14a and a second drain pan 67b located below the rear body 14b. The first drain pan 67a is supported by the main body 28a in front of the blower fan 24. Condensation water generated on the surface of the front body 14a flows into the first drain pan 67a due to gravity. The first drain pan 67a is gently sloped toward the lowest outlet (not shown). Piping connected to the outdoor unit 13 is connected to the outlet. When the blower fan 24 rotates, the air flowing from the intake port 33 toward the blower fan 24 is blocked by the first drain pan 67a and does not reach the third region 68 of the indoor heat exchanger 14.

The second drain pan 67b is supported by the main body 28a behind the blower fan 24. Condensation water generated on the surface of the rear body 14b flows into the second drain pan 67b due to gravity. The second drain pan 67b is gently sloped toward the lowest outlet (not shown). Piping connected to the outdoor unit 13 is connected to the outlet. When the blower fan 24 rotates, the second drain pan 67b blocks the airflow path from the intake port 33 along the back wall of the main body 28a. Therefore, when the blower fan 24 rotates, the air flowing in from the intake port 33 along the back wall of the main body 28a cannot pass through and flow toward the second drain pan 67b, and thus does not reach the fourth region 69 of the indoor heat exchanger 14.

(3) Configuration of the control system As shown in Figure 6, the control unit 27 includes a cooling operation unit 78 that manages the operation of cooling operation, a heating operation unit 79 that manages the operation of heating operation, and a heating and sterilization operation unit 81 that manages the heating and sterilization operation. The cooling operation unit 78, heating operation unit 79, and heating and sterilization operation unit 81 are connected to a valve switching control unit 82, an opening degree control unit 83, a compressor control unit 84, a first blower fan control unit 85, a second blower fan control unit 86, and a wind direction control unit 87. The valve switching control unit 82 is connected to the four-way valve 18. The valve switching control unit 82 outputs a control signal to the four-way valve 18. The four-way valve 18 is switched between a first position and a second position according to the received control signal. In the first position, the four-way valve 18 connects the second port 18b and the third port 18c to each other and connects the first port 18a and the fourth port 18d to each other. In the second position, the four-way valve 18 connects the second port 18b and the fourth port 18d to each other, and connects the first port 18a and the third port 18c to each other. The valve switching control unit 82 generates a control signal to identify the first or second position in response to instructions from the cooling operation unit 78, the heating operation unit 79, or the heating and sterilization operation unit 81.

The opening degree control unit 83 is connected to the expansion valve 17. The opening degree control unit 83 outputs a control signal to the expansion valve 17. The opening degree of the expansion valve 17 is adjusted according to the received control signal. The control signal specifies the opening degree of the expansion valve 17. In setting the temperature of the indoor heat exchanger 14, the adjustment of the opening degree of the expansion valve 17 is used in conjunction with the control of the compressor 15, which will be described later. The opening degree control unit 83 generates a control signal that specifies the opening degree of the expansion valve 17 in response to instructions from the cooling operation unit 78, the heating operation unit 79, or the heating and sterilization operation unit 81.

The compressor control unit 84 is connected to the compressor 15. The compressor control unit 84 outputs a control signal to the compressor 15. The operation of the compressor 15 is controlled according to the received control signal. For example, the control signal specifies the rotational speed of the compressor 15. When setting the temperature of the indoor heat exchanger 14, the operation of the compressor 15 is adjusted along with the opening degree of the expansion valve 17. The compressor control unit 84 generates a control signal that specifies the rotational speed of the compressor 15 in response to instructions from the cooling operation unit 78, the heating operation unit 79, or the heating and sterilization operation unit 81.

The first blower fan control unit 85 is connected to the blower fan 23 of the outdoor unit 13. The first blower fan control unit 85 outputs a control signal to the blower fan 23. The rotation of the blower fan 23 is controlled according to the received control signal. The control signal, for example, switches the rotation and stationary state of the blower fan 23. When the blower fan 23 is rotating, the control signal specifies the rotation speed of the blower fan 23. The amount of thermal energy exchanged in the outdoor heat exchanger 16 is adjusted according to the airflow based on the rotation of the blower fan 23. The first blower fan control unit 85 generates control signals to stop operation or specify the rotation speed of the blower fan 23 in response to instructions from the cooling operation unit 78, the heating operation unit 79, or the heating and sterilization operation unit 81.

The second blower fan control unit 86 is connected to the blower fan 24 of the indoor unit 12. The second blower fan control unit 86 outputs a control signal to the blower fan 24. The rotation of the blower fan 24 is controlled according to the received control signal. The control signal, for example, switches the rotation and stationary state of the blower fan 24. When the blower fan 24 is rotating, the control signal specifies the rotation speed of the blower fan 24. The amount of thermal energy exchanged in the indoor heat exchanger 14 is adjusted according to the airflow based on the rotation of the blower fan 24. The second blower fan control unit 86 generates control signals to stop operation or specify the rotation speed of the blower fan 24 in response to instructions from the cooling operation unit 78, the heating operation unit 79, or the heating and sterilization operation unit 81.

The airflow direction control unit 87 is connected to the upper and lower airflow deflectors 25a and 25b. The airflow direction control unit 87 outputs control signals to the upper and lower airflow deflectors 25a and 25b. The orientation of the upper and lower airflow deflectors 25a and 25b around the rotation axes 32a and 32b is controlled according to the received control signals. For example, the control signals specify the angles of the upper and lower airflow deflectors 25a and 25b around the rotation axes 32a and 32b. At the minimum angle, the upper and lower airflow deflectors 25a and 25b close the air outlet 29. At the maximum angle, the upper and lower airflow deflectors 25a and 25b open the air outlet 29 to the maximum extent. The airflow direction control unit 87 generates control signals that specify the angles of the upper and lower airflow deflectors 25a and 25b in response to instructions from the cooling operation unit 78, the heating operation unit 79, or the heating and sterilization operation unit 81.

The cooling operation unit 78 instructs the valve switching control unit 82 to establish cooling operation. The cooling operation unit 78 instructs the opening control unit 83 and the compressor control unit 84 to control the opening of the expansion valve 17 and the rotation speed of the compressor 15 according to the set temperature during cooling operation. The heating operation unit 79 instructs the valve switching control unit 82 to establish heating operation. The heating operation unit 79 instructs the opening control unit 83 and the compressor control unit 84 to control the opening of the expansion valve 17 and the rotation speed of the compressor 15 according to the set temperature during heating operation. In this way, the indoor unit 12 generates an airflow of cold or warm air passing through the indoor heat exchanger 14 in accordance with the rotation of the blower fan 24, and blows out the airflow of cold or warm air from the outlet 29. The outdoor unit 13 supplies refrigerant to the indoor heat exchanger 14 in an adjusted phase state according to the operation of the compressor 15 and the expansion valve 17.

The heating and sterilization unit 81 comprises a heating control unit 81a that performs a heating cycle operation and maintains the temperature of the indoor heat exchanger 14 at 55 degrees Celsius or higher for a predetermined duration (e.g., 10 minutes), a pre-treatment control unit 81b that performs a fan operation (hereinafter referred to as "first fan operation") prior to the heating cycle operation of the heating control unit 81a, and a post-treatment control unit 81c that performs a fan operation (hereinafter referred to as "second fan operation") after the heating cycle operation of the heating control unit 81a. During the fan operation, a pause state is established in the compressor 15. That is, the operation of the compressor 15 stops. Here, during the heating cycle operation, the same refrigerant circulation as during heating operation is established in the refrigeration circuit 19. A temperature sensor 26a and a humidity sensor 26b are connected to the heating and sterilization unit 81. The temperature sensor 26a and humidity sensor 26b may also be used as sensors for the cooling or heating operation of the air conditioner 11.

Here, the heating and sterilization unit 81 sets a limit temperature corresponding to the upper limit temperature of the operating temperature range of the compressor 15. The compressor 15 has an operating temperature range that guarantees its operation. When the temperature of the compressor 15 is maintained below the upper limit temperature of the operating temperature range, the operation of the compressor 15 is reliably ensured. When the operation of the compressor 15 is suppressed during heating operation, a rise in the temperature of the compressor 15 can be avoided. In this case, the temperature of the indoor heat exchanger 14 is used for temperature control of the compressor 15 in the air conditioner 11. The temperature of the indoor heat exchanger 14 is detected by the temperature sensor 26a. When the temperature of the indoor heat exchanger 14 exceeds the limit temperature, the heating and sterilization unit 81 suppresses the operation of the compressor 15. The heating and sterilization unit 81 may also stop the operation of the compressor 15. In this way, the compressor 15 is protected. The limit temperature is set, for example, to 59 degrees Celsius.

A reference table 88 is connected to the second blower fan control unit 86. The reference table 88 holds a first value 88a that defines the rotational speed of the blower fan 24 per minute, a second value 88b that defines a rotational speed of the blower fan 24 per minute that is less than the first value 88a, a third value 88c that defines a rotational speed of the blower fan 24 per minute that is less than the second value 88b, and a fourth value 88d that defines a rotational speed of the blower fan 24 per minute that is less than the first value 88a and greater than the second value 88b. When the blower fan 24 rotates at the rotational speed of the first value 88a, an airflow of the first volume is blown out from the outlet 29. When the blower fan 24 rotates at the rotational speed of the second value 88b, an airflow of the second volume, which is less than the first volume, is blown out from the outlet 29. When the blower fan 24 rotates at a rotational speed of the third value 88c, an airflow with a third airflow volume smaller than the second airflow volume is blown out from the outlet 29. When the blower fan 24 rotates at a rotational speed of the fourth value 88d, an airflow with an airflow volume smaller than the first airflow volume and larger than the second airflow volume is blown out from the outlet 29. The reference table 88 can be constructed in a storage medium such as memory. Here, the fifth value 88e, which defines the rotational speed of the blower fan 24 per minute that is smaller than the third value 88c, is stored in the reference table 88. When the blower fan 24 rotates at a rotational speed of the fifth value 88e, an airflow with an airflow volume smaller than the third airflow volume is blown out from the outlet 29.

The reference table 88 stores the first time value 89a, which specifies the airflow time for the heating cycle operation performed by the heating control unit 81a; the second time value 89b, which specifies the airflow time for the first airflow operation performed by the pre-treatment control unit 81b; and the third time value 89c, which specifies the airflow time for the second airflow operation performed by the post-treatment control unit 81c. Here, the first values 88a to 5th values 88e and the first time values 89a to 3rd time values 89c are each specified by a single fixed value.

The control unit 27 includes a timer 91 connected to the cooling operation unit 78, the heating operation unit 79, and the heat sterilization operation unit 81. The timer 91 measures time according to the instructions of the cooling operation unit 78, the heating operation unit 79, or the heat sterilization operation unit 81. The operating time of the cooling or heating operation, the heating cycle operation time of the heating control unit 81a, the airflow time of the pre-treatment control unit 81b, and the airflow time of the post-treatment control unit 81c are measured. The timer 91 outputs a timing signal to the heat sterilization operation unit 81. The timing signal specifies the value of the measured time. The heat sterilization operation unit 81 controls the operation of the valve switching control unit 82, the compressor control unit 84, and the second airflow fan control unit 86 according to the measured time value.

The control unit 27 includes a receiving unit 92 connected to the cooling operation unit 78, the heating operation unit 79, and the heating and sterilization operation unit 81. The receiving unit 92 communicates with the remote control (operation unit) 93. Optical signals and radio waves are used for communication. The remote control 93 is placed in the indoor space and sends operation signals to the indoor unit 12.

As shown in Figure 7, the remote control 93 includes a group of operation buttons 95 and a display panel 96 embedded on the surface of the housing 94. The group of operation buttons 95 includes buttons such as "Menu" button 95a, "Select" button 95b, "Back" button 95c, "Cooling" button 95d, "Heating" button 95e, "Dehumidification" button 95f, and "Stop" button 95g. When each operation button is pressed, an electrical signal specific to that button 95a-95g is output. These electrical signals are converted into optical signals or radio waves by a transmission circuit and transmitted to the receiving unit 92 of the indoor unit 12.

The display panel 96 displays the type of operation, such as "Automatic," "Cooling," "Heating," "Dehumidification," and "Ventilation," as well as the set temperature, according to the instructions of the drawing circuit. In addition, a menu list (icons) is displayed in response to the operation of the "Menu" button 95a. By selecting from the options displayed in the menu list with the "OK" button 95b, it is possible to decide whether to execute or not execute other operations, including the heating sterilization operation. For example, if the "Menu" button 95a is operated during cooling or heating operation, the menu list 97 is displayed on the display panel 96, as shown in Figure 7(B). If "Airflow" is selected in response to the operation of the "OK" button 95b, the "Airflow" list 98 is displayed, as shown in Figure 7(C). The user can select the desired airflow through the operation of the "OK" button 95b. For example, if "Strong Airflow" is selected, the second fan control unit 86 obtains a first value 88a from the reference table 88. The second fan control unit 86 controls the operation of the fan 24 according to the first value 88a. Similarly, if "Weak Airflow" is selected, a second value 88b is obtained. When "Gentle Breeze" is selected, the third value 88c is acquired. When "Silent" is selected, the fifth value 88e is acquired. Similarly, the user can select "Heat Sterilization" from the menu list. When "Heat Sterilization" is selected on the remote control 93, the control unit 27 performs the heat sterilization operation.

(4) Heat sterilization operation Next, the heat sterilization operation performed by the air conditioner 11 will be explained. If the air conditioner 11 is operating in cooling mode prior to the start of the heat sterilization operation, the temperature inside the indoor unit 12 will be lower than the room temperature, and condensation will occur inside the housing of the indoor unit 12 depending on the humidity of the indoor space. At this time, the heat dissipation fins 42b are arranged at intervals that cause capillary action of condensation water according to surface tension, so condensation water accumulates in the gaps between the heat dissipation fins 42b. Due to the airflow caused by the rotation of the blower fan 24 and gravity, the condensation water partially flows from the indoor heat exchanger 14 to the first and second drain pans 67a and 67b.

The heat sterilization operation is initiated, for example, in response to user remote control operation. Based on the user's operation of the "Menu" button 95a, a menu list is displayed on the remote control 93's display panel 96. The user selects "Heat Sterilization" from the menu list. A radio signal identifying "Heat Sterilization" is transmitted from the remote control 93 to the indoor unit 12's receiver 92. The heat sterilization operation unit 81 begins the heat sterilization operation upon receiving the "Heat Sterilization" signal. Prior to the heat sterilization operation, the cooling operation unit 78 terminates the cooling operation.

As shown in Figure 8, when the heat sterilization operation is started, in step S1, the pre-treatment control unit 81b performs a first blower operation. During the first blower operation, the pre-treatment control unit 81b obtains the fourth value 88d and the second time value 89b from the reference table 88. The pre-treatment control unit 81b stops the operation of the compressor 15. The pre-treatment control unit 81b controls the operation of the blower fan 24 based on the fourth value 88d and the second time value 89b via the second blower fan control unit 86. The pre-treatment control unit 81b may use, for example, a timer 91 to time the second time value 89b. In the first region 64, second region 66, third region 68, and fourth region 69, condensation remains in the gaps of the heat dissipation fins 42b because airflow does not pass through these areas. Moisture adhering to the surface of the heat dissipation fins 42b outside of the gaps is removed.

Once the first blower operation is complete, in step S2, the heating control unit 81a performs a heating cycle operation. For the heating cycle operation, the heating control unit 81a obtains the third value 88c and the first time value 89a from the reference table 88. The heating control unit 81a controls the operation of the four-way valve 18, expansion valve 17, and compressor 15 through the valve switching control unit 82, opening degree control unit 83, and compressor control unit 84 to establish heating operation. For the heating cycle operation, the heating control unit 81a controls the operation of the blower fan 24 based on the third value 88c and the first time value 89a through the second blower fan control unit 86. For timing the first time value 89a, the heating control unit 81a may use, for example, a timer 91.

When the heating cycle operation is completed, in step S3, the post-processing control unit 81c performs a second blower operation. For the second blower operation, the post-processing control unit 81c obtains the second value 88b and the third time value 89c from the reference table 88. The post-processing control unit 81c stops the operation of the compressor 15. The post-processing control unit 81c controls the operation of the blower fan 24 based on the second value 88b and the third time value 89c through the second blower fan control unit 86. For timing the third time value 89c, the post-processing control unit 81c may use, for example, a timer 91.

The heating control unit 81a maintains the temperature of the indoor heat exchanger 14 at 55 degrees Celsius or higher for a predetermined duration (= first time value 89a). Since a shorter time is desirable for the heat sterilization operation, the first time value 89a is set to the minimum time required to kill 90% or more of mold and bacteria (e.g., E. coli). Here, based on known experimental results, the minimum time is set to 5 minutes. From the perspective of protecting the compressor 15, the temperature of the indoor heat exchanger 14 is set to 59 degrees Celsius or lower.

During the first fan operation, the fourth value 88d and the second time value 89b are set to values that allow condensation water to be maintained in the gaps of the indoor heat exchanger 14 during the heating cycle operation of the heating control unit 81a. Therefore, during the first fan operation, condensation water remains in the gaps of the indoor heat exchanger 14 to a level sufficient to maintain condensation water in the gaps of the indoor heat exchanger 14 during the heating cycle operation of the heating control unit 81a. Moisture adhering to the surface of the heat dissipation fins 42b is removed. In the indoor heat exchanger 14, evaporation of condensation water is suppressed in areas where airflow does not pass, such as the first region 64, second region 66, third region 68, and fourth region 69. Therefore, the amount of remaining condensation water can be adjusted by adjusting the areas of the first region 64, second region 66, third region 68, and fourth region 69 during the design phase.

During the second fan operation, the second value 88b and the third time value 89c are set to values that can at least sufficiently cool the indoor heat exchanger 14 after the heating cycle operation. Preferably, the indoor heat exchanger 14 is cooled to room temperature. Here, the condensation water remaining on the indoor heat exchanger 14 in response to the second fan operation vaporizes. The surface of the indoor heat exchanger 14 dries.

In this embodiment, since condensation is maintained during the heating cycle operation of the heat sterilization function, moist heat sterilization is achieved when the indoor heat exchanger 14 is maintained at 55 degrees Celsius or higher. Mold and bacteria are effectively sterilized in the condensation. Mold growth is suppressed. Moreover, since the fan operation is performed prior to the heating cycle operation, the rise in humidity in the blown airflow at the start of the heating cycle operation is suppressed. As a result, occupants do not have to come into contact with humid, warm air. The comfort of the occupants' skin is maintained well. On the other hand, if the first fan operation is continued excessively, condensation will evaporate from the gaps in the indoor heat exchanger 14, and sufficient sterilization effect will not be achieved during the heating cycle operation. Conversely, if the surface of the indoor heat exchanger 14 is not sufficiently dry during the first fan operation, the humidity of the blown airflow will rise significantly at the start of the heating cycle operation, and the comfort of the occupants' skin will deteriorate.

In this embodiment, the post-processing control unit 81 performs a second fan operation after the heating cycle operation of the heat sterilization operation to cool the indoor heat exchanger 14 and vaporize condensation water from the gaps in the indoor heat exchanger 14. In this way, the inside of the indoor unit 12 is dried, and mold growth is suppressed (prevented).

The indoor heat exchanger 14 has a set limit temperature to protect the compressor 15 from excessive heating. If the temperature of the indoor heat exchanger 14 exceeds the limit temperature, the operation of the compressor 15 is suppressed. Therefore, if the temperature of the indoor heat exchanger 14 is kept below the limit temperature, the operation of the compressor 15 is not suppressed, and the heating of the indoor heat exchanger 14 is maintained properly. In addition, because the indoor heat exchanger 14 has a limit temperature, excessively warm airflow is prevented from being blown from the indoor unit 12 into the room. This prevents deterioration of the indoor living environment.

The pre-processing control unit 81a according to this embodiment has a reference table 88 that defines the rotational speed per minute and the blowing time of the blower fan 24 for the first blowing operation, each using a single fixed value. Condensation water flows down the surface of the indoor heat exchanger 14 due to gravity. Therefore, the amount of moisture adhering to the surface of the indoor heat exchanger 14 can be anticipated in advance. Based on the anticipated amount of moisture, the rotational speed per minute and the blowing time of the blower fan 24 can be determined. In this way, the processing operation of the pre-processing control unit 81a is simplified.

In this embodiment, during the second fan operation, although the indoor heat exchanger 14 reaches a high temperature after the heating cycle operation, the fan 24 rotates at a lower rotational speed per minute (3rd value 88c) than the rotational speed during the first fan operation (4th value 88d). Therefore, the airflow rate of the blown-out air is suppressed, and as a result, the comfort level of occupants is maintained. Since the indoor heat exchanger 14 is cooled during the second fan operation, even if cooling operation is subsequently performed, it can be started in a short time.

During the heating sterilization operation, if the airflow is most suppressed during the heating cycle, occupants will not be exposed to warm airflow. Therefore, their skin comfort will be maintained. During the second fan operation, if a larger airflow is ensured than during the heating cycle, the drying and temperature decrease of the indoor heat exchanger 14 will be accelerated. Therefore, the processing time will be shortened. During the second fan operation, the temperature of the discharged airflow decreases, so even if the airflow increases, the skin comfort of occupants can be maintained.

During cooling operation by the cooling unit 78 and heating operation by the heating unit 79, the airflow of the indoor unit 12 can be adjusted according to the user's selection. The rotation speed of the blower fan 24 is pre-set for each user selection when adjusting the airflow. The user selection is set on the remote control 93. When the rotation speed set on the remote control 93 is used during the heating cycle operation for heat sterilization or the second blower operation, the rotation speed remains the same as during normal control, thus simplifying the control process. The load on the control unit 27 is reduced. Since there is no need to add new values to the reference table 88, memory capacity can also be saved.

In this embodiment, during the first blower operation, the rotation speed of the blower fan 24 is set to a fourth value that defines the rotation speed corresponding to an airflow less than "strong wind" and greater than "weak wind." Thus, a rotation speed different from the user's selection is assigned during the first blower operation. A rotation speed suitable for the first blower operation can be set other than the user's selection. In this way, the time of the first blower operation can be shortened as much as possible. The heating and sterilization operation can be completed in the shortest possible time. However, during the first blower operation, the pre-processing control unit 81b may be set to a first value corresponding to "strong wind" which is greater than "weak wind" during the second blower operation. In this way, if the rotation speed set on the remote control 93 is used during the first blower operation, the rotation speed remains the same as during normal control, thus simplifying the control.

In setting the fourth value 88d and the second time value 89b for the first fan operation, for example, the rate of humidity change per minute in the discharged airflow may be referenced. The inventors measured the rate of humidity change per minute at elapsed time intervals during the first fan operation and the heating cycle operation. The air conditioner 11 was installed in the laboratory for the measurements. Relative humidity was measured every minute in the laboratory. For the first fan operation, the airflow rate was set to "low" based on the second value 88b. For the heating cycle operation, the airflow rate was set to "very low" based on the third value 88c.

As shown by the solid line in Figure 9, it was found that when the first fan operation is continued for a specific operating time, the humidity change rate per minute in the discharged airflow reaches a peak value of 101 before converging to a value within a predetermined range. Subsequently, when the heating cycle operation is performed following the first fan operation, the humidity change rate per minute in the discharged airflow again reaches a peak value of 102 upon the start of the heating cycle operation. Thus, it was confirmed that the peak values 101 and 102 are dispersed between the first fan operation and the heating cycle operation. On the other hand, when the first fan operation is not continued until a peak value of 101 appears, and the system switches from the first fan operation to the heating cycle operation, a peak value 103, which is larger than either peak value 101 or 102, appears upon the start of the heating cycle operation, as shown by the dotted line in Figure 9. Since this increase in the humidity change rate per minute worsens the skin sensation of occupants, reducing the peak value leads to greater comfort for occupants. In other words, if the first fan operation is performed until the humidity change rate per minute in the discharged airflow reaches a peak value of 101 and then converges to a value within a predetermined range, the increase in humidity due to the heating cycle operation will be suppressed even if the heating cycle operation is subsequently performed. Therefore, the comfort level of the occupants will be maintained. On the other hand, if the heating cycle operation is started after the humidity change rate per minute reaches a peak value but before it settles within the predetermined range, the humidity change rate per minute will increase significantly more than either of the peak values 101 or 102. Here, when the humidity change rate per minute in the discharged airflow reaches a peak value of 101 and then converges to within ±1.0%, the heating control unit 81a switches from the first fan operation to the heating cycle operation.

In the heating cycle operation of the heat sterilization operation, as mentioned above, it is not necessary to maintain condensation on the indoor heat exchanger 14 for the entire duration of the heating cycle. It is sufficient to maintain the temperature of the indoor heat exchanger 14 at 55 degrees Celsius or higher for a predetermined duration, thereby maintaining condensation on the indoor heat exchanger 14. In this case, the rotation speed and airflow time of the blower fan 24 are not fixed values, but rather determined according to the amount of condensation generated in the indoor heat exchanger 14 during cooling operation. For example, the pre-treatment control unit 81b can determine the rotation speed of the blower fan 24 based on the operating time of the cooling operation. Since the amount of condensation generated in the indoor heat exchanger 14 depends on the operating time of the cooling operation, if the rotation speed of the blower fan 24 during airflow operation is determined according to the operating time of the cooling operation measured by the control unit 27, an optimal level of humidity can be established in the indoor heat exchanger 14 at the end of the airflow operation.

Thus, since the rotation speed of the blower fan 24 is determined according to the amount of condensation water during the first blower operation, an optimal level of humidity can be established in the indoor heat exchanger 14 for maintaining condensation water. Therefore, the blower operation time can be shortened. If the first blower operation is continued for an excessive amount of time, the condensation water will evaporate from the indoor heat exchanger 14, and sufficient sterilization effect will not be achieved during the heating cycle operation of the heating sterilization operation. Conversely, if the surface of the indoor heat exchanger 14 is not sufficiently dry during the first blower operation, the humidity of the blown airflow will rise significantly at the start of the heating cycle operation, worsening the skin comfort of occupants.

The pre-processing control unit 81b may determine the rotation speed of the blower fan 24 based on the humidity detected by the humidity sensor 26b. Since the amount of condensation water generated in the indoor heat exchanger 14 depends on the humidity inside the indoor unit 12, if the rotation speed of the blower fan 24 during the first blower operation is determined according to the measurement value of the humidity sensor 26b, an optimal humidity level can be established in the indoor heat exchanger 14 at the end of the first blower operation.

11…Air conditioner, 12…Indoor unit, 13…Outdoor unit, 14…Heat exchanger (indoor heat exchanger), 15…Compressor, 17…Expansion valve, 24…(Indoor unit) Blower fan, 26b…Humidity sensor, 29…Air outlet, 81a…Heating control unit, 81b…Pre-treatment control unit, 81c…Post-treatment control unit, 88…Reference table.

Claims (2)

An indoor unit that generates an airflow that passes through a heat exchanger in accordance with the rotation of a blower fan and blows out the airflow from an outlet,
An outdoor unit that supplies refrigerant to the heat exchanger according to the operation of the compressor and expansion valve,
A heating control unit operates a heating cycle while maintaining condensation water in the gap at the end of the heat exchanger, and maintains the temperature of the heat exchanger at 55 degrees Celsius or higher.
An air conditioner characterized by comprising a pre-treatment control unit that, prior to the operation of the heating cycle, performs a blower operation corresponding to the area of the end region in order to remove moisture adhering to the surface of the heat exchanger, while leaving the condensation water in the gap so as to maintain the condensation water in the gap for the entire duration of the heating cycle operation. An air conditioner according to claim 1, wherein the heat exchanger comprises an inner body positioned facing the blower fan and an outer body positioned to overlap the outside of the inner body, and the gap is partitioned by the inner body .