Air conditioner apparatus

Abstract: An air conditioner apparatus wherein the range of fluctuation of the difference between the room temperature and the desired preset temperature is divided into a plurality of zones, a variable capacity compressor (18) being driven at frequencies respectively corresponding to these zones, and a heater (13) provided in an internal unit when a drying operation mode is selected and the room temperature is in a zone lower than the desired preset temperatures. The apparatus is further equipped with a switch (24) that shifts the frequencies corresponding to the zones in the drying operation mode in the direction of an increasing dehumidification capacity.

Description: The present invention relates, in general, to an air conditioner apparatus that dehumidifies by controlling current to a heater provided in an internal unit in a range in which the room temperature is lower than its set value. In most modern air conditioners, usually the range of fluctuation of the difference between the room temperature and the set temperature value is divided into a plurality of zones. Thus, the compressor for refrigerant circulation is driven at a frequency corresponding to the respective zone. In this case, usually the compressor is stopped in the zone in which the room temperature is lower than the set value. However, compressor improvements have expanded the low end of the range of speeds in which the compressor operation is possible. Recently, air conditioners have appeared in which the compressor is operated at low speed even in the zone in which the room temperature is lower than the set value. There are also air conditioners in which a heater is provided in the internal unit of the air conditioner. Thus, comfort is increased by controlling current to this heater in the initial period of the heating operation mode, or in the zone in which room temperature is lower than the set value in the drying operation mode. For example, this type of air conditioner is found in Japanese Utility Model Disclosure (Kokai) No. 54-125152. In this conventional air conditioner, the room temperature is controlled by an ON/OFF operation of an electric heater in the drying operation mode. Furthermore, the compressor operating frequency in the zone in which the room temperature is lower than the set value is determined by the occupant of the room. In this connection, in the case of a typical domestic air conditioner intended for a room with a floor area of about 10 square meters (≒ 110 ft²), assuming that the occupant of the room is alone, the compressor operating frequency is selected to be 12 Hz. In this case, even if the room is occupied by three people, the compressor continues to operate with the same frequency so long as the room temperature does not exceed the set value, so that even if the humidity is felt to be high, it is not possible to alter the dehumidifying capacity. US-A-4,813,474 discloses an air conditioning apparatus comprising a refrigeration system including a variable capacity compressor, an external heat exchanger, a decompression device, and an internal heat exchanger, all of which are coupled to each other; a heater arranged in association with the internal heat exchanger; temperature setting means for setting a desired room temperature; temperature detecting means for detecting an actual room temperature; a controller for operating in a drying operation mode to output first control data for controlling the capacity of the variable capacity compressor by comparing temperature data preset by the temperature setting device with temperature data detected by the temperature detecting device, and to output second control data for controlling current to the heater when the room temperature is lower than the preset room temperature in the drying operation mode. US-A-4,744,223 discloses an air conditioning apparatus comprising means for altering the temperature of the internal heat exchanger in response to the selection of a low humidity control mode by increasing the capacity of the compressor. The present invention seeks to provide an improved air conditioner apparatus wherein the dehumidifying capacity can be raised without altering the set room temperature. According to a first aspect of the present invention, there is provided a method of controlling ambient humidity in a predetermined region, comprising: comparing a preset temperature with an ambient temperature to produce a temperature difference indication; controlling an operating capacity of a variable capacity compressor coupled with a heat exchanger for affecting said ambient humidity in response to said temperature difference indication; controlling a heater interacting with said heat exchanger in response to said temperature difference indication; the method being characterised by: in a drying operation mode, further altering said operating capacity of said variable capacity compressor in response to a selected condition independent of said ambient temperature. According to a second aspect of the present invention, there is provided apparatus for carrying out the method in accordance with the first aspect of the invention, the apparatus comprising: a refrigeration system including a variable capacity compressor, an external heat exchanger, a decompression device, and an internal heat exchanger, all of which are coupled to each other; a heater arranged in association with said internal heat exchanger; temperature setting means for setting a desired room temperature; temperature detecting means for detecting an actual room temperature; means for selecting a drying operation mode in which dehumidification control of a room is to be performed; control means responding to said drying operation mode, for outputting first control data for controlling a capacity of said variable capacity compressor by comparing said desired room temperature set by said temperature setting means with said actual room temperature detected by said temperature detecting means, and outputting second control data for controlling current to said heater when said actual room temperature is lower than said desired room temperature in said drying operation mode; characterised in that the apparatus further comprises: means for selecting a condition in said drying operation mode, whereby said capacity may be increased by controlling said variable capacity compressor independently of said ambient temperature. A presently preferred embodiment of the invention will now be described in conjunction with the accompanying drawings of which: Fig. 1 is a block diagram showing the general layout of an embodiment of the present invention; Fig. 2(a) and Fig. 2(b) are diagrams in explanation of the operation of the embodiment shown in Fig. 1, each showing the relationship between temperature difference and compressor operating frequency; and Fig. 3 is a graph showing the relationships between mean room humidity and mean temperature and time, in explanation of the action of the present invention. The preferred embodiment of the present invention will now be described in more detail with reference to the accompanying drawings. In Fig. 1, a heater 13 is connected to an AC power source 11 through the contact 12a of a relay 12. A converter 14 is also connected in parallel to the AC power source 11. The heater 13 is provided in the indoor unit. The heater 13 performs dehumidification in the drying operation mode, and, in the initial period of the heating operation mode, heats up the cold air that is blown out. The converter 14 consists of a diode bridge circuit that rectifies the AC input and outputs DC. A smoothing capacitor 15 is connected on the output side of the converter 14. Furthermore, an inverter 16 is connected to the converter 14. The inverter 16 converts the smoothed DC to AC of variable voltage and variable frequency. The AC output of this inverter 16 is applied to a compressor motor 17. The compressor motor 17 drives a compressor 18. The input side of the compressor 18 is connected to one side of an external heat exchanger 19. An external fan device 20 is disposed close to the external heat exchanger 19 for supplying air to the external heat exchanger 19. The other side of the external heat exchanger 19 is connected to one side of internal heat exchanger 22 through a decompression device, e.g., an expansion valve 21. The aforementioned heater 13 is arranged in the vicinity of the internal heat exchanger 22. An internal fan device 23 is disposed close to the internal heat exchanger 22 for supplying air to the internal heat exchanger 22. The other side of the internal heat exchanger 22 is connected to the output side of the compressor 18. There are further provided a dehumidification switch 24, a room temperature sensor 25, a temperature setter 26 and a capacity up button 27. The dehumidification switch 24 is utilized for selecting the drying operation mode. The room temperature sensor 25 detects a room temperature. The room temperature setter 26 is utilized for setting room temperature. The capacity up button 27 is utilized for increasing dehumidifying capacity. In this case, the dehumidification switch 24, the temperature setter 26 and the capacity up button 27 are provided in a remote controller, but to simplify the description the elements associated with the remote control are omitted. The room temperature sensor 25 and the temperature setter 26 are connected to a temperature difference detecting device 28. The temperature difference detecting device 28 calculates the deviation between the room temperature and the set temperature value. A temperature difference compensation device 29 is connected to the temperature difference detecting device 28. The temperature difference compensation device 29 delivers an output compensating for the actual temperature difference in response to an ON signal from the capacity up button 27. The temperature difference compensation device 29 also is connected to a frequency determining device 30. The frequency determining device 30 determines the frequency of the compressor operation in accordance with each of the zones into which the range of fluctuation of temperature difference is divided and outputs a determined frequency signal. An inverter control device 31 controls the inverter 16 in accordance with the determined frequency signal. The frequency determining device 30 has a data table which stores frequency data corresponding to temperature differences for each operating mode. Thus, the frequency determining device 30 determines the compressor operating frequency by using this table. The temperature difference detection device 28 is connected to a heater ON/OFF determination device 32. The heater ON/OFF determination device 32 determines whether the heater 13 is to be connected or not depending on whether or not the drying operation mode is selected. Depending on its output, a relay drive device 33 controls excitation of the relay 12. In operation, AC from the AC power source 11 is rectified by the converter 14, then smoothed by the smoothing capacitor 15. After that, smoothed current is converted to AC of variable voltage and variable frequency by the inverter 16 and fed to the compressor motor 17. The temperature difference detection device 28 calculates the deviation between the value detected by the room temperature sensor 25 and the value set by the temperature setter 26. The deviation is supplied to the temperature difference compensation device 29. If the capacity up button 27 has not been turned ON, the temperature difference signal is supplied without modification to the frequency determining device 30, through the temperature difference compensation device 29. The frequency determining device 30 then selects a data table in accordance with the operating mode, and, using this data table, determines the compressor operating frequency corresponding to the temperature difference. Thus, the inverter control device 31 controls the inverter 16 such that three-phase AC of this frequency is output. The data tables selected in the drying operation mode by turning dehumidification switch 24 ON are as follows: Based on the output of the temperature difference detection device 28, the heater ON/OFF determination device 32 outputs a heater ON command in the range where the room temperature is lower than the set temperature, under the condition that the drying operation mode has been selected by the dehumidification switch 24. Thus, the relay drive device 33 excites the relay 12. As a result, as shown in Fig. 2(a), the compressor motor 17 is operated with the frequency of the data table shown in Table 1 when the temperature difference is on a falling trend and is operated with the frequency of the data table shown in Table 2 when the temperature difference is on a rising trend. When the room temperature is less than the set value, the dehumidifying operation is performed by connecting the heater 13 while the compressor motor 17 is operated at 12 Hz. In this state, if the capacity up button 27 is turned ON because it is felt that the humidity is high, the temperature difference compensation device 29 delivers an output in which a zone step is added to the temperature difference signal from the temperature difference detection device 28. The frequency determining device 30 therefore outputs a frequency signal that is shifted in the direction of increasing capacity from the frequency signal that would normally correspond to the actual temperature difference. As a result, as shown in Fig. 2(b), the compressor motor 17 is driven with increased dehumidification capacity, with the frequency shifted by a step corresponding to one zone. Fig. 3 shows how the mean room humidity and the mean temperature change, depending on whether or not the capacity up button 27 is turned ON, in the drying operating mode. In this case, it is assumed that the drying operation is performed from time t₀, when the occupancy of the room is high and there is high humidity. Accordingly, when the capacity up button 27 is pressed at time t₁, only the humidity is lowered, the temperature staying unaltered. It has been found that, with an ordinary domestic air conditioner, for a room with a floor area of 10 square meters, if there are three occupants, the humidity can be kept in a satisfactory range by operating the compressor motor 17 at 16 Hz. Thus, with this embodiment, the dehumidification capacity can be raised simply by operating a switch when it is felt that the humidity in the room is high. In the above embodiment, a correction is applied to the temperature difference signal that is output from the temperature difference detection device 28 so as to shift the frequency in the direction of increasing capacity by a step corresponding to one zone. Instead, it would be possible to prepare a data table for the frequency determining means 30 giving higher frequencies corresponding to each zone, so that when the capacity up button 27 is operated, the compressor drive frequency would be determined using this data table with higher frequencies.

Claims: A method of controlling ambient humidity in a predetermined region, comprising: comparing a preset temperature with an ambient temperature to produce a temperature difference indication; controlling an operating capacity of a variable capacity compressor coupled with a heat exchanger for affecting said ambient humidity in response to said temperature difference indication; controlling a heater interacting with said heat exchanger in response to said temperature difference indication; the method being characterised by: in a drying operation mode, further altering said operating capacity of said variable capacity compressor in response to a selected condition independent of said ambient temperature. A method as claimed in claim 1, wherein said selected condition is inputted by an occupant of said predetermined region. Air conditioning apparatus for carrying out the method according to claim 1 or 2, the apparatus comprising: a refrigeration system including a variable capacity compressor (18), an external heat exchanger (19), a decompression device (21), and an internal heat exchanger (22), all of which are coupled to each other; a heater (13) arranged in association with said internal heat exchanger; temperature setting means (26) for setting a desired room temperature; temperature detecting means (25) for detecting an actual room temperature; means (24) for selecting a drying operation mode in which dehumidification control of a room is to be performed; control means (28, 29, 30, 32), responding to said drying operation mode, for outputting first control data for controlling a capacity of said variable capacity compressor by comparing said desired room temperature set by said temperature setting means with said actual room temperature detected by said temperature detecting means, and outputting second control data for controlling current to said heater when said actual room temperature is lower than said desired room temperature in said drying operation mode; characterised in that the apparatus further comprises: means (27) for selecting a condition in said drying operation mode, whereby said capacity may be increased by controlling said variable capacity compressor (18) independently of said ambient temperature. An apparatus according to claim 3, further including an internal fan device (23) for supplying air flow to said internal heat exchanger. An apparatus according to claim 3 or 4, further including an external fan device (20) for supplying air flow to said external heat exchanger (19). An apparatus according to claim 3, 4 or 5, wherein said decompression device (21) is an expansion valve. An apparatus according to one of claims 3 to 6, further including an inverter circuit (16) for supplying variable frequency driving power to said compressor (18). An apparatus according to claim 7, further including a compressor motor (17) for driving said compressor. An apparatus according to one of claims 3 to 8, further including a heater driver (33, 12) for driving said heater (13) in response to said second control data from said control means. An apparatus according to one of claims 3 to 9, wherein said control means includes means (28, 29) for calculating a temperature difference between said actual and desired temperatures as a plurality of divided zones and means (30) for determining said first control data in accordance with each of said zones. An apparatus according to claim 10, wherein said determining means (30) includes a data table in which said first control data corresponding to an operating mode of said apparatus and said temperature difference between said actual and desired temperatures are pre-stored. An apparatus according to claim 10, wherein said data table stores different values of said first control data respectively corresponding to tendencies of said temperature difference to increase or decrease.

Inventors: NAGASAWA ATSUSHI C O INTELLECT, NAGASAWA, ATSUSHI, C/O INTELLECTUAL PROPERTY DIV.
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1990
Main classification: F24F3
IPC codes: F24F3, F24F11