Patent Application
20100125370
1. Field of the Invention
The present invention relates to an air-conditioning apparatus configured to include a plurality of air conditioners. More particularly, the present invention relates to the air-conditioning apparatus that allows the plurality of air conditioners to communicate with each other, although they generally operate individually, to achieve efficient energy saving performance and promote comfort.
2. Description of the Related Art
Air conditioners for business applications are usually installed in large spaces of offices or stores. It is a common practice, in such cases, that a group of air conditioners is operated and controlled by one remote control. An example of this case is disclosed in JP 07-167519 A.
With reference to JP 07-167519 A, a plurality of air conditioners is operated individually based on instructions by a single remote control so that room temperatures reach a set temperature by heating or cooling. There is nothing more than that.
Therefore, an air conditioner installed in a location near an entrance or a window where higher air-conditioning load is required compared to other parts of a room requires high capacity. A high capacity operation results in low efficiency (=capacity/input). Therefore, if the air conditioners are operated individually, then the room temperature becomes nonuniform. This may reduce the overall efficiency of the group of air conditioners.
In addition, the heat exchanger of the outdoor unit of an air conditioner may be frosted during heating when outside temperatures are low, and frosts may grow. Therefore, defrosting is required at regular intervals. A defrost operation is generally performed by running the outdoor unit exclusively by a refrigerating cycle for cooling while the operation of the indoor unit sending warm air into a room is suspended. Since the heating operation is thus temporarily stopped for defrosting, room temperatures are reduced. Furthermore, those air conditioners may reach a point to start defrosting almost simultaneously since they are controlled to start heating operations simultaneously as a group. If the group of air conditioners warming a room together perform their defrost operations all at once, then a serious reduction in room temperatures may create less comfort.
In addition to that, a low-load cooling operation may be performed in a rainy season or the like when the discomfort index is high because the temperature is not so high but the humidity is high. In such a low-load cooling operation, each air conditioner operates at a high evaporation temperature and a high sensible heat ratio (sensible heat capacity/full capacity) during cooling, i.e., an operation with low dehumidification capacity. Therefore, room air is not sufficiently dehumidified, which cannot improve comfort. Then, if the set temperature of room air is lowered for more comfort, then the power consumption is increased and above all the user of the air conditioner would feel cold. This creates less comfort.
The present invention is directed to solving problems such as those described above. It is an object of the present invention to reduce the power consumption of an air-conditioning apparatus, by allowing a plurality of air conditioners to communicate with each other, and thereby leveling their air-conditioning capacities with no load variations involved by temperature nonuniformity.
It is another object of the present invention to prevent less comfort by a reduction in room temperatures, by allowing a plurality of air conditioners to communicate with each other, and thereby preventing two or more air conditioners from performing their defrost operations simultaneously during heating.
It is still another object of the present invention to promote comfort, by allowing a plurality of air conditioners to communicate with each other during cooling, and thereby adjusting air-conditioning load so that several air conditioners perform a cooling operation with high capacity at a low evaporation temperature and a low sensitive heat ratio, and the rest of the plurality of air conditioners perform their cooling operations with less capacity. This means that not every air conditioner performs the same operation with low capacity at a high evaporation temperature and a high sensible heat ratio. This may allow an air-conditioning apparatus to perform a low-load cooling operation, which provides an overall dehumidification performance acceptable without causing room temperatures to decrease.
It is still another object of the present invention to allow an air conditioning apparatus to pretend to perform a reheating dehumidifying operation, by allowing a plurality of air conditioners to communicate with each other during cooling, and thereby allowing several air conditioners among a plurality of air conditioners to perform a heating operation.
These and other objects of the embodiments of the present invention are accomplished by the present invention as hereinafter described in further detail.
According to one aspect of the present invention, an air-conditioning apparatus may include a plurality of air conditioners and a computing section for control that allows the plurality of air conditioners to communicate with each other to level the air-conditioning capacities of the air conditioners based on air-conditioning load detected by each of the plurality of air conditioners. Each air conditioner may include an indoor unit and an outdoor unit that form a closed refrigerating cycle. The indoor units of the air conditioners may be installed in an area to be air-conditioned.
According to another aspect of the present invention, an air-conditioning apparatus may include a plurality of air conditioners and a computing section for control that allows the plurality of air conditioners to communicate with each other to include an air conditioner that performs a dehumidification capacity increase operation, and an air conditioner that adjusts air-conditioning load to prevent room temperatures from decreasing below a set temperature, upon receipt of an instruction to start cooling. Each of the plurality of air conditioners may include an indoor unit and an outdoor unit that form a closed refrigerating cycle. The indoor units of the air conditioners may be installed in an area to be air-conditioned.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals indicate like devices throughout the several views.
As shown in
The example of
The air conditioners may be of a ceiling cassette type, for example. Generally, a ceiling cassette air conditioner means a separate type air conditioner that is equipped with a ceiling mounted indoor unit and an outdoor unit connected to the indoor unit. The indoor unit and the outdoor unit forms a closed refrigeration cycle.
Each air conditioner of the air-conditioning apparatus 100 shown in
The indoor units 2a, 2b, . . . and 2x and the outdoor units 1a, 1b, . . . and 1x communicate with one another via the internal/external communication lines of the pipes/wires 3 and the connecting wires 4. This may allow a computing section for control mentioned below to obtain statistics on the operational frequencies of compressors installed in the outdoor units 1a, 1b, . . . and 1x.
The compressors in the outdoor units 1a, 1b, . . . and 1x may be inverter driven. Therefore, the operational frequency is not fixed, but varies based on instructions. The compressor may be a rotary compressor, a scroll compressor, or the like.
AS shown in
This computing section for control may be installed in one of the outdoor unit 1a, 1b, . . . and 1x, the indoor units 2a, 2b, . . . and 2x, and the remote control 5. Alternatively, a separate device equipped with the computing section for control may be newly added.
More specifically, as shown in
With reference to
Then, an average suction air temperature of each indoor unit 2a, 2b, 2x is compared with the set temperature to determine whether cooling capacity or heating capacity is sufficient enough (S12). The set temperature of air sucked at the suction intake is preset by a user by the remote control 5.
During cooling, it is determined that the cooling capacity is sufficient enough if average suction air temperature of each indoor unit 2a, 2b, . . . , 2x≦set temperature.
During heating, it is determined that the heating capacity is sufficient enough if average suction air temperature of each indoor unit 2a, 2b, . . . , 2x≧set temperature.
If it is determined in S12 that the air-conditioning capacity (i.e., cooling capacity or heating capacity) is sufficient, then the current air-conditioning capacity is maintained or reduced (S13).
If it is determined that air-conditioning capacity is not sufficient, then every connected outdoor unit is controlled to increase its air-conditioning capacity (S14). Air-conditioning capacity is not sufficient if average suction air temperature of each indoor unit 2a, 2b, . . . , 2x>set temperature during cooling, or if average suction air temperature of each indoor unit 2a, 2b, . . . , 2x<set temperature during heating.
The fixed time operation is completed here (S15), and the same operation is repeated afterward.
In the case of varying compressor frequency, air-conditioning capacity and input may vary as follows: The air-conditioning capacity at a maximum frequency is around 2.5 times higher than that at a minimum frequency, for example. The input at the maximum frequency is around five times more than that at the minimum frequency, for example. Therefore, the COP (Coefficient of Performance=air-conditioning capacity/input) at the maximum frequency is around a half of that at the minimum frequency.
Thus, the air-conditioning apparatus 100 of this embodiment may achieve a reduction in power consumption by allowing the plurality of air conditioners to communicate with one another and thereby leveling their air-conditioning capacities with no load variations involved by temperature nonuniformity.
Such a load leveling operation may allow for a reduction in power consumption of the air-conditioning apparatus described in this and other embodiments characterized as follows: The air-conditioning apparatus 100 may be configured to include the plurality of air conditioners and the computing section for control, where each air conditioner includes the indoor unit 2a, 2b, . . . , 2x and the outdoor unit 1a, 1b, . . . , 1x that form a closed refrigeration cycle. The indoor units 1a, 1b, . . . and 1x of the plurality of air conditioners are installed in an area to be air-conditioned. The computing section for control may allow the plurality of air conditioners to communicate with one another, thereby leveling their air-conditioning capacities based on air-conditioning load detected by each air conditioner.
The plurality of air conditioners of the air-conditioning apparatus 100 of
When a fixed time heating operation is started (S20), the temperature of the outdoor heat exchanger of each air conditioner is measured to have statistics (S21). The temperature of the outdoor heat exchanger may be measured by a temperature detector (e.g., a thermistor) attached to the outdoor heat exchanger, which is not shown in the figures.
It is determined (S22) whether each air conditioner has approached a defrost permission time, based on the temperature of the outdoor heat exchanger of the air conditioner that is measured to have statistics in S21.
The “defrost permission time” may be defined as follows: When an air conditioner starts heating, the temperature of the outdoor heat exchanger as an evaporator is reduced gradually. In such a situation, time of heating periods when the temperature of the outdoor heat exchanger is under a predetermined “defrost permission temperature Tdef” (e.g., −5° C. to −2° C.) is accumulated. A predetermined value (e.g., 60 minutes) of an accumulated time of heating periods when the temperature is under the predetermined temperature below zero (e.g., −5° C. to −2° C.) is defined as the “defrost permission time”.
If it is determined in S22 that two or more air conditioners where the accumulated time of heating periods that satisfies the “temperature of outdoor heat exchanger≦defrost permission temperature Tdef” have approached the predetermined defrost permission time, then it is determined whether there is an air conditioner that is performing a defrost operation (S23).
If it is determined in S23 that there is no air conditioner that is performing a defrost operation, then an air conditioner that is the nearest to the defrost permission time is started to perform a defrost operation (S25).
The fixed time heating operation is completed here (S27), and the process returns to S20.
The defrost operation may be performed by running the outdoor unit exclusively by a refrigerating cycle for cooling while the operation of the indoor unit sending warm air into the room is stopped (the fan is stopped). More specifically, the outdoor heat exchanger of the outdoor unit may operate as a condenser.
If it is determined in S23 that an air conditioner is performing a defrost operation, then it is determined whether the temperature of the outdoor heat exchanger of the air conditioner where the accumulated time of heating periods that satisfies “temperature of outdoor heat exchanger≦defrost permission temperature Tdef” has approached the defrost permission time is below a forced defrost temperature (e.g., −20° C. to −10° C.) (S24).
If it is determined in S24 that the temperature of the outdoor heat exchanger of the air conditioner where the accumulated time of heating periods that satisfies “temperature of outdoor heat exchanger≦defrost permission temperature Tdef” has approached the defrost permission time is below the forced defrost temperature, then the air conditioner having the temperature determined to be below the forced defrost temperature is started to perform a defrost operation, regardless of whether or not there is another air conditioner that is performing a defrost operation (S26).
If it is determined in S24 that the temperature of the outdoor heat exchanger of the air conditioner where the accumulated time of heating periods that satisfies “temperature of outdoor heat exchanger≦defrost permission temperature Tdef” has approached the defrost permission time is not below the forced defrost temperature, meaning that there is an air conditioner in the state of a defrost operation, then no defrost operation is started and the process returns to S21 for the following reason. In such a situation where there is an air conditioner that is performing a defrost operation, if another air conditioner performs a defrost operation, then the overall heating capacity of the air-conditioning apparatus 100 is reduced.
If it is determined in S22 that there is no or a single air conditioner where the accumulated time of heating periods that satisfies “temperature of outdoor heat exchanger≦defrost permission temperature Tdef” has approached the predetermined defrost permission time, then it is determined whether the temperature of the outdoor heat exchanger of the single air conditioner is below the forced defrost temperature (e.g., −20° C. to −10° C.) (S24).
If the temperature of the outdoor heat exchanger of the single air conditioner is below the forced defrost temperature (e.g., −20° C. to −10° C.), then the air conditioner is started to perform a defrost operation (S26).
If it is determined in S24 that the temperature of the outdoor heat exchanger of the single air conditioner is not below the forced defrost temperature, then no defrost operation is started and the process returns S21.
After S26, the fixed time heating operation is completed (S27), like S25, and the process returns to S20.
The above described defrost operation is performed by the computing section for control. The computing section for control may be installed in one of the outdoor units 1a, 1b, . . . and 1x, the indoor units 2a, 2b, . . . and 2x, and the remote control 5. Alternatively, a separate device equipped with the computing section for control may be newly added.
As described above, the air conditioners may thus be controlled during heating such that an air conditioner does not start its defrost operation unless the temperature of the outdoor heat exchanger is below the forced defrost temperature while another air conditioner is in the middle of a defrost operation, or starts its defrost operation at an earlier stage when another air conditioner is likely to start its defrost operation simultaneously. The air conditioners that are allowed to communicate with one another may thereby prevent two or more air conditioners from performing simultaneous defrost operations, as much as possible, during heating when outside temperatures are low. This may prevent the air-conditioning apparatus 100 from having insufficient heating capacity and thereby avoid a reduction in room temperatures and less comfort.
The plurality of air conditioners of the air-conditioning apparatus 100 of
If a person in a room (i.e., an area to be air-conditioned) issues an instruction to give priority to dehumidification by a remote control 5, then the air-conditioning capacities of several air conditioners are increased and their evaporation temperatures are reduced. The air-conditioning capacities of the rest of the air conditioners are reduced, or their operations are switched from cooling to blowing, in order to adjust increased overall air-conditioning capacity, thereby preventing an excessive reduction in room temperatures.
Such an operation to reduce air-conditioning capacities for adjusting overall air-conditioning capacity at the time of an increase in overall air-conditioning capacity is a load adjustment operation performed to prevent room temperatures from decreasing below the set temperature.
The “dehumidification capacity increase operation” may be defined as a cooling operation performed at a low evaporation temperature and a low sensitive heat ratio (sensitive heat capacity/full capacity).
With reference to
Subsequently, the fixed time operation is started (S32). The suction air temperatures of each indoor unit 2a, 2b, . . . , 2x are measured by a temperature detector (e.g., a thermistor) installed at a suction intake of each indoor unit, which is not shown in the figures, to have statistics (S33).
Then, the average suction air temperature of each indoor unit 2a, 2b, . . . , 2x is compared with the set temperature (S34).
During cooling, the air-conditioning capacity is determined to be sufficient if average suction air temperature of each indoor unit 2a, 2b, . . . , 2x≦set temperature.
During heating, the air-conditioning capacity is determined to be sufficient if average suction air temperature of each indoor unit 2a, 2b, . . . , 2x≧set temperature.
If it is determined in S34 that air-conditioning capacity is sufficient, then it is determined whether air-conditioning capacity has exceeded the limit (S35).
In that case, the operation of an indoor unit not performing its dehumidification capacity increase operation is stopped. Then, if average suction air temperature of each indoor unit<the set temperature−Tdif, where Tdif is a predetermined temperature difference, it is determined that air-conditioning capacity has exceeded the limit.
If it is determined that air-conditioning capacity has exceeded the limit, then the number of air conditioners performing their dehumidification capacity increase operations is reduced (S38) and the process returns to S32.
If it is determined that air-conditioning capacity has not exceeded the limit, then the current air-conditioning capacity is maintained (S37), then the fixed time operation is completed (S39), and the process returns to S32.
If it is determined in S34 that air-conditioning capacity is not sufficient, then the air-conditioning capacity of an air conditioner not performing its dehumidification capacity increase operation is increased (S36), then the air-conditioning capacity is maintained (S37), then the fixed time operation is completed (S39), and the process returns to S32.
If a specific air conditioner is always set to increase its cooling capacity, then the user near by the indoor unit of that specific air conditioner would feel less comfortable with cold. Given this fact, air conditioners are controlled to change their roles of increasing dehumidification capacity and adjusting (temperature) capacity alternately in every 10 to 20 minutes, thereby preventing less comfort.
The dehumidification control operation described above is performed by the computing section for control, as is the case with the first embodiment. The computing section for control may be installed in one of the outdoor units 1a, 1b, . . . and 1x, the indoor units 2a, 2b, . . . and 2x, and the remote control 5. Alternatively, a separate device equipped with the computing section for control may be newly added.
During dehumidification, the dehumidification capacity is large when the evaporation temperature is reduced. Therefore, the volume of airflow of each indoor unit may be reduced. This control may prevent, as much as possible, the user near by the indoor unit of an air conditioner from feeling less comfortable with cold. Wind direction may also be controlled so that the volume of airflow is reduced as much as possible, for better comfort. It is desirable therefore that the wind direction is oriented at such an angle that wind does not blow against a recipient.
With reference to the air-conditioning apparatus 100 of the third embodiment, when a person in a room (i.e., an area to be air-conditioned) issues instructions to further raise the priority of dehumidification by the remote control 5, at least one of the plurality of air conditioners may be controlled to perform a heating operation. This may allow the amount of dehumidification to be increased without reducing overall room temperatures. The volume of airflow and wind direction may also be controlled for better comfort in this case. It is also desirable to set the volume of airflow and wind direction so that warm air does not blow against a recipient.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-293474 | Nov 2008 | JP | national |
