EP2835595A1

EP2835595A1 - Control device, method, and program, and multi-type air conditioning system comprising same

Info

Publication number: EP2835595A1
Application number: EP13772647.7A
Authority: EP
Inventors: Takahiro Kato; Keisuke Mitoma; Atsushi Enya
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2012-04-06
Filing date: 2013-03-18
Publication date: 2015-02-11
Also published as: CN104081131A; JP5916489B2; CN104081131B; JP2013217550A; EP2835595A4; WO2013150885A1

Abstract

An indoor fan of an indoor unit in a thermo-OFF state is operated intermittently while reducing a necessary amount of refrigerant and suppressing an increase in receiver capacity. Provided is a control unit (41) for controlling operation of a packaged air conditioning system (1) in which a plurality of indoor units (7) are connected to an outdoor unit (2). During a heating operation, if an indoor fan (73) of each of the indoor units (7A, 7B) performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, the control unit (41) forms a plurality of groups of the indoor units for matching timings for the intermittent operation of the respective indoor units, shifts the timing for the intermittent operation for each group, and controls assignment of the indoor units (7A, 7B) to the groups so that total model capacities of the indoor units (7A, 7B) that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.

Description

{Technical Field}

The present invention relates to a control device, a control method, a control program, and a packaged air conditioning system including the control device.

{Background Art}

A packaged air conditioning system used for air-conditioning a building or the like is configured so that a plurality of indoor units are connected to one outdoor unit. In the packaged air conditioning system of this type, the operation is controlled to be started/stopped per indoor unit, and a thermostat is controlled to be turned ON/OFF depending on whether an indoor temperature reaches a set temperature range.
In heating operation, if the thermostat is turned off after the indoor temperature reaches the set temperature range, the corresponding indoor unit does not require a heating capability. However, if the other indoor units connected to the common outdoor unit are in operation, the compressor of the outdoor unit continuous to operate and refrigerant, therefore, continuously flows in the system as a whole. Owing to this, in the indoor unit in which the thermostat is turned off or the indoor unit that is stopped to operate, the expansion valve of the indoor unit is not set closed but slightly opened to allow for the flow of the refrigerant so as to prevent the refrigerant from being accumulated in the indoor unit.
The following situation may possibly occur in the packaged air conditioning system. In the indoor unit in the state in which the thermostat has been turned off in the heating operation, even when the indoor temperature falls out of the set temperature range and the thermostat should be turned on to restart heating, the temperature sensor of the indoor unit does not operate properly to turn on the thermostat because of warm air filled in the indoor unit. To avoid such a situation, the conventional packaged air conditioning system has been designed such that the indoor fan of each indoor unit can perform an intermittent operation to be appropriately turned ON/OFF even in the state in which the thermostat is turned off so as to be able to detect the indoor temperature.
For example, PTL 1 discloses the following technique. Among a plurality of indoor units each in a state in which a thermostat is turned off, the number of the simultaneously-driven indoor fans of the indoor units is limited, and the timing of driving the indoor fans is made different from that of driving the other fans, thereby suppressing a sharp decrease in the temperature of the air blown off from the indoor units.

{Citation List}

{Patent Literature}

{PTL 1}
The Publication of Japanese Patent No. 3778117

{Summary of Invention}

{Technical Problem}

However, in PTL 1, the following problems unavoidably occur. The refrigerant is condensed in each indoor unit by allowing the indoor fan of the indoor unit to operate in the state in which the thermostat is turned off, resulting in an increase in the amount of the refrigerant necessary for the system. For this reason, there is a problem that a difference between a maximum and a minimum of the necessary amount of refrigerant becomes large and a receiver capacity increases accordingly.
The present invention has been made in view of aforementioned situations, and an object of the present invention is to provide a control device, a control method, a control program, and a packaged air conditioning system including the control device capable of allowing an indoor fan of each indoor unit in a state in which a thermostat is turned off to perform an intermittent operation while reducing a necessary amount of refrigerant and suppressing an increase in receiver capacity.

{Solution to Problem}

A first aspect of the present invention is a control device for controlling operation of a packaged air conditioning system in which a plurality of indoor units are connected to an outdoor unit, wherein during a heating operation, if an indoor fan of each of the indoor units performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, the control device forms a plurality of groups of the indoor units for matching timings for the intermittent operation of the respective indoor units, shifts the timing for the intermittent operation for each group, and controls assignment of the indoor units to the groups so that total model capacities of the indoor units that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.
In accordance with the first aspect, during a heating operation, if an indoor fan of each of the indoor units performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, the plurality of groups of the indoor units for matching the timings for the intermittent operation of the respective indoor units are formed, the timing for the intermittent operation is shifted for each group, and assignment of the indoor units to the groups is controlled so that the total model capacities of the indoor units that are included in the respective groups and are in the thermo-OFF state become approximately equal to each other.
In this way, to the respective groups which have different timings for the intermittent operation, the indoor units are assigned so that each total model capacity of the indoor units becomes equal. Accordingly, the amounts of refrigerant accumulating in a heat exchanger of the indoor unit during the on-period of the indoor fan in the thermo-OFF mode during a heating operation are averaged, whereby the necessary amount of refrigerant can be minimized. Therefore, a necessary amount of refrigerant can be reduced, and the receiver capacity can also be reduced as a result.
In the first aspect, the control device preferably sets a different timing of an on-period in the intermittent operation for each of the groups so that the on-periods of the groups do not overlap with each other.
The intermittent operation is performed with the on-period of the indoor fan varied in the different groups, and accordingly, the amount of refrigerant accumulating in the heat exchanger of the indoor unit during the on-period of the indoor fan can be suppressed to ensure a reduction in necessary amount of refrigerant.
In the first aspect, the control device preferably assigns the indoor unit that is switched from a thermo-ON state to a thermo-OFF state to the group with a smallest total model capacity of the indoor units, of the plurality of groups.
The indoor unit that has just entered the thermo-OFF state is assigned to the group with the smallest total model capacity, and accordingly, it is possible to avoid a case where a total model capacity of a certain group becomes large, and the respective model capacities of the groups can be approximated to equalization.
In the first aspect, if there is a group in which the total model capacity of the indoor units is equal to or larger than a predetermined ratio relative to the total model capacities of all the groups, the indoor unit with a smallest model capacity in the group with the total model capacity equal to or larger than the predetermined ratio is preferably assigned to the group with the smallest total model capacity.
Consequently, the respective total model capacities of the groups can be equalized.
In the first aspect, if one of the indoor units has a model capacity equal to or larger than a predetermined ratio relative to the total model capacities of all the groups, another indoor unit than the indoor unit with the model capacity equal to or larger than the predetermined ratio is preferably assigned to a group that is different from the group that includes the indoor unit with the model capacity equal to or larger than the predetermined ratio.
Consequently, a case where only a certain group has a large total model capacity can be avoided, and the increase in necessary amount of refrigerant can be suppressed.
A second aspect of the present invention is a packaged air conditioning system having any control device mentioned above.
A third aspect of the present invention is a control method for controlling operation of a packaged air conditioning system in which a plurality of indoor units are connected to an outdoor unit, comprising: during a heating operation, if an indoor fan of each of the indoor units performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, forming a plurality of groups of the indoor units for matching timings for the intermittent operation of the respective indoor units; shifting the timing for the intermittent operation for each group; and controlling assignment of the indoor units to the groups so that total model capacities of the indoor units that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.
A fourth aspect of the present invention is a control program for controlling operation of a packaged air conditioning system in which a plurality of indoor units are connected to an outdoor unit, the program causing a computer to, during a heating operation, if an indoor fan of each of the indoor units performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, form a plurality of groups of the indoor units for matching timings for the intermittent operation of the respective indoor units, shift the timing for the intermittent operation for each group, and control assignment of the indoor units to the groups so that total model capacities of the indoor units that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.

{Advantageous Effects of Invention}

The present invention can provide the effect that an indoor fan of an indoor unit in a state in which a thermostat is turned off can be operated intermittently while reducing a necessary amount of refrigerant and suppressing an increase in receiver capacity.

{Brief Description of Drawings}

{Fig. 1}
Fig. 1 is a schematic configuration diagram of a refrigerant circuit in an air conditioner according to an embodiment of the present invention.
{Fig. 2}
Fig. 2(a) is a diagram illustrating the transition of an amount of refrigerant in a first indoor unit, Fig. 2(b) is a diagram illustrating the transition of an amount of refrigerant in a second indoor unit, Fig. 2(c) is a diagram illustrating the transition of an amount of refrigerant in a third indoor unit, and Fig. 2(d) is a diagram illustrating the transition of total amounts of refrigerant in the first to third indoor units, corresponding to an ON/OFF state of an indoor fan and a thermo-ON/OFF state, according to the conventional control method.
{Fig. 3}
Fig. 3(a) is a diagram illustrating the transition of an amount of refrigerant in a first indoor unit, Fig. 3(b) is a diagram illustrating the transition of an amount of refrigerant in a second indoor unit, Fig. 3(c) is a diagram illustrating the transition of an amount of refrigerant in a third indoor unit, and Fig. 3(d) is a diagram illustrating the transition of total amounts of refrigerant in the first to third indoor units, corresponding to an ON/OFF state of an indoor fan and a thermo-ON/OFF state, according to the embodiment of the present invention.
{Fig. 4}
Fig. 4 is a diagram illustrating an example of ON/OFF states of indoor fans of three groups in an intermittent operation, according to a modification of the embodiment of the present invention.

{Description of Embodiments}

A control device, a control method, a control program, and a packaged air conditioning system including the control device according to an embodiment of the present invention will be described hereinafter with reference to the drawings.
Fig. 1 is a schematic configuration diagram of a packaged air conditioning system 1 including a control device according to the embodiment of the present invention, with a refrigerant cycle also shown therein.
The packaged air conditioning system 1 includes one outdoor unit 2, a gas-side pipe 4 and a liquid-side pipe 5 led out from the outdoor unit 2, and a plurality of indoor units 7 connected in parallel between the gas-side pipe 4 and the liquid-side pipe 5 via branch units 6. In Fig. 1, the number of the indoor units 7 is two, that is, indoor units 7A and 7B are shown by way of example. In the present embodiment, however, a case will be described where a third indoor unit 7C, not illustrated, is additionally provided. The indoor units will be described as "indoor units 7" hereinafter unless specified otherwise.
The outdoor unit 2 includes an inverter-driven compressor 21 that compresses refrigerant, an oil separator 22 that separates chiller oil from refrigerant gas, a four-way change-over valve 23 changing over a circulation direction of the refrigerant, an outdoor heat exchanger 24 that exchanges heat between the refrigerant and outdoor air, a supercooling coil 25 configured integrally with the outdoor heat exchanger 24, an outdoor electric expansion valve for heating (EEVH) 26, a receiver 27 that stores therein liquid refrigerant, a supercooling heat exchanger 28 that supercools the liquid refrigerant, an electric expansion valve for supercooling (EEVSC) 29 that controls an amount of the refrigerant branched to the supercooling heat exchanger 28, an accumulator 30 that separates the liquid refrigerant from the refrigerant gas absorbed into the compressor 21 so as to absorb only gas refrigerant into the compressor 21, a gas-side operating valve 31, and a liquid-side operating valve 32.
The constituent elements of the outdoor unit 2 described above are connected to one another via refrigerant pipes such as a discharge pipe 33A, a gas pipe 33B, a liquid pipe 33C, a gas pipe 33D, an suction pipe 33E, and an supercooling branch pipe 33F by a well-known manner, and constitute an outdoor refrigerant circuit 34. The outdoor unit 2 also includes an outdoor fan 35 that sends the outdoor air to the outdoor heat exchanger 24.
Furthermore, for returning the chiller oil separated from the discharged refrigerant gas within the oil separator 22 to the compressor 21 by a predetermined amount at a time, a parallel circuit constituted by a first oil return circuit 37 that includes a fixed throttle (throttle) 36 such as a capillary tube and a second return circuit 40 that includes a solenoid valve 38 and a fixed throttle (throttle) 39 such as a capillary tube is connected between the oil separator 22 and the suction pipe 33E connected to the compressor 21.
The gas-side pipe 4 and the liquid-side pipe 5 are the refrigerant pipes connected to the gas-side operating valve 31 and the liquid-side operating valve 32 of the outdoor unit 2. At a time of installing the packaged air conditioning system 1 on site in a construction phase, lengths of the gas-side pipe 4 and the liquid-side pipe 5 are set depending on distances between the outdoor unit 2 and the indoor units 7A and 7B connected to the outdoor unit 2. An appropriate number of branch units 6 are provided halfway along the gas-side pipe 4 and the liquid-side pipe 5, and an appropriate number of indoor units 7A and 7B are each connected to the gas-side pipe 4 and the liquid-side pipe 5 via these branch units 6. A closed one-system refrigerant cycle 3 is thereby constituted.
Each of the indoor units 7A and 7B includes an indoor heat exchanger 71 that exchanges heat between the refrigerant and indoor air to be used for indoor air-conditioning, an indoor electric expansion valve (indoor-unit electric expansion valve) for cooling (EEVC) 72, and an indoor fan 73 that circulates the indoor air through the indoor heat exchanger 71. Each of the indoor units 7A and 7B is connected to the branch units 6 via an indoor-side branch gas pipe 4A and an indoor-side branch liquid pipe 5A.
In the aforementioned packaged air conditioner 1, a cooling operation is performed as follows.
The high-temperature and high-pressure refrigerant gas compressed by the compressor 21 is discharged to the discharge pipe 33A, and the oil separator 22 separates the chiller oil contained in the refrigerant. Thereafter, the refrigerant gas circulates toward the gas pipe 33B via the four-way change-over valve 23, exchanges heat with the outdoor air sent by the outdoor fan 35, and is condensed into liquid refrigerant in the outdoor heat exchanger 24. After being further cooled by the supercooling coil 25, this liquid refrigerant passes through the outdoor electric expansion valve 26 and is temporarily stored in the receiver 27.
The liquid refrigerant the circulating amount of which is regulated in the receiver 27 is branched in part to the supercooling branch pipe 33F while being distributed through the supercooling heat exchanger 28 via the liquid pipe 33C. The resultant liquid refrigerant exchanges heat with the refrigerant adiabatically expanded by the electric expansion valve for supercooling (EEVSC) 29, and is thereby supercooled. This liquid refrigerant is led out from the outdoor unit 2 to the liquid-side pipe 5 via the liquid-side operating valve 32. The liquid refrigerant led out to the liquid-side pipe 5 is further branched to the branch liquid pipes 5A and 5B of the respective indoor units 7A and 7B by the branch units 6.
The liquid refrigerant branched to the branch liquid pipes 5A and 5B flows into the indoor units 7A and 7B adiabatically expanded by the indoor electric expansion valve (EEVC) 72, in each of which the liquid refrigerant flows, as a gas-liquid two-phase flow, into the indoor heat exchanger 71. In the indoor heat exchanger 71, the indoor air circulated by the indoor fan 73 exchanges heat with the refrigerant, and the indoor air is cooled and used for indoor cooling. On the other hand, the refrigerant is transformed into gas, the gas refrigerant reaches the branch units 6 via the branch gas pipes 4A and 4B, and the gas refrigerant meets with the refrigerant gas from the other indoor units in the gas-side pipe 4.
The refrigerant gas meeting together in the gas-side pipe 4 returns toward the outdoor unit 2, reaches the suction pipe 33E via the gas-side operating valve 31, the gas pipe 33D, and the four-way change-over valve 23, meets with the refrigerant gas from the branch pipe 33F, and is then led into the accumulator 30. In the accumulator 30, the liquid refrigerant contained in the refrigerant gas is separated and only the gas refrigerant is absorbed into the compressor 21. This refrigerant is compressed again by in the compressor 21. Thus, the cooling operation is performed by repeating the aforementioned cycle.
Meanwhile, heating operation is performed as follows.
The high-temperature and high-pressure refrigerant gas compressed by the compressor 21 is discharged to the discharge pipe 33A, the oil separator 22 separates the chiller oil contained in the refrigerant, and then the refrigerant gas circulates toward the gas pipe 33D by the four-way change-over valve 23. This refrigerant is led out from the outdoor unit 2 via the gas-side operating valve 31 and the gas-side pipe 4, and further led into the indoor units 7A and 7B via the indoor-side branch gas pipes 4A and 4B, respectively.
The high-temperature and high-pressure refrigerant gas led into the indoor units 7A and 7B exchange heat with the indoor air circulated by the indoor fan 73, and the indoor air is heated and used for indoor heating in the indoor heat exchanger 71. The liquid refrigerant resulting from condensation in the indoor heat exchanger 71 reaches the branch units 6 via the indoor electric expansion valve (EEVC) 72 and the branch liquid pipe 5A or 5B, meets with the refrigerant from the other indoor units, and then returns to the outdoor unit 2 via the liquid-side pipe 5.
The refrigerant back to the outdoor unit 2 reaches the supercooling heat exchanger 28 via the liquid-side operating valve 32 and the liquid pipe 33C, and is supercooled similarly to the cooling operation. Thereafter, the resultant refrigerant flows into the receiver 27 and is temporarily stored in the receiver 27, whereby the circulating amount of the refrigerant is regulated in the receiver 27. This liquid refrigerant is supplied to the outdoor electric expansion valve (EEVH) 26 via the liquid pipe 33C and adiabatically expanded in the outdoor electric expansion valve (EEVH) 26, and the liquid refrigerant then flows into the outdoor heat exchanger 24 via the supercooling coil 25.
In the outdoor heat exchanger 24, the refrigerant exchanges heat with the outdoor air sent from the outdoor fan 35, and the refrigerant absorbs the heat from the outdoor air and is evaporated into gas. This refrigerant led out from the outdoor heat exchanger 24 meets with the refrigerant from the supercooling branch pipe 33F via the gas pipe 33B, the four-way change-over valve 23, and the suction pipe 33E, and is led into the accumulator 30. In the accumulator 30, the liquid refrigerant contained in the refrigerant gas is separated and only the gas refrigerant is absorbed into the compressor 21. This refrigerant is compressed again by the compressor 21. Thus, the heating operation is performed by repeating the aforementioned cycle.
During the cooling operation or the heating operation described above, the chiller oil separated from the discharged refrigerant gas in the oil separator 22 is returned toward the compressor 21 via the first oil return circuit 37 including the fixed throttle 36 and the second oil return circuit 40 including the solenoid valve 38 and the fixed throttle 39 that are connected to each other in parallel. This secures the chiller oil of a certain amount in the compressor 21, and allows slide portions in the compressor 21 to be lubricated. The solenoid valve 38 provided in the second oil return circuit 40 is configured to be able to regulate an amount of the oil separated in the oil separator 22 by which the separated oil is returned toward the compressor 21 by being actuated to be opened/closed at appropriate timing during the steady cooling operation or heating operation.
In a thermo-OFF mode during a heating operation, in which the suction temperature of air reaches a target temperature and the refrigerant is not circulated, if the indoor fan 73 of the indoor unit 7 performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time, a control unit 41 forms a plurality of groups of indoor units for matching timings for the intermittent operation of the respective indoor units, shifts the timing for the intermittent operation for each group, and controls assignment of the indoor units 7 to the groups so that total model capacities of the indoor units 7 that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.
The control unit 41 preferably sets a different timing of an on-period of the indoor fans 73 in the intermittent operation for each group so that the respective on-periods do not overlap with each other. Note that the control unit 41 sets, for each group, a timing for ON/OFF operation of the indoor fans 73 of the indoor units 7 in the group in the intermittent operation.
Furthermore, the control unit 41 stores information on a model capacity of each of the indoor units 7, and therefore, if there is an indoor unit 7 that is switched from a thermo-ON state to a thermo-OFF state, the control unit 41 calculates a total model capacity of indoor units 7 included in each group, and assigns the indoor unit 7 that is switched to the thermo-OFF state to the group with the smallest total model capacity.
Hereinafter, a description will be given of a group formation and a method for controlling an intermittent operation by the control unit 41, showing a specific example in comparison with the conventional control method. The control unit 41 sets in advance an on-period and an off-period of the indoor fan 73, and controls the intermittent operation for turning ON/OFF the indoor fan 73 based on the set periods. In the present embodiment, a case will be illustrated where the intermittent operation is performed with the on-period of three minutes and the off-period of five minutes, however, time lengths for the on-period and the off-period are not particularly limited.
Fig. 2 illustrates the transition of the thermo-ON/OFF states of three indoor units 7 (black triangle marks), the ON/OFF states of indoor fans 73 (black round marks), an amount of refrigerant estimated depending on the thermo-ON/OFF states (black rhombus marks), according to the conventional control method. The three indoor units 7 are described each as a first indoor unit 7A, a second indoor unit 7B and a third indoor unit 7C. Also, the amounts of refrigerant illustrated here are an approximate amount of accumulating refrigerant in a heat exchanger of the indoor unit 7. Fig. 2(a) illustrates the transition of an amount of refrigerant in the first indoor unit 7A, Fig. 2(b) illustrates the transition of an amount of refrigerant in the second indoor unit 7B, and Fig. 2(c) illustrates the transition of an amount of refrigerant in the third indoor unit 7C. Fig. 2(d) illustrates the transition of total amounts of refrigerant in all the indoor units 7A, 7B, and 7C.
Furthermore, the thermo-ON/OFF state and the ON/OFF state of the indoor fan 73 are shown overlapping on the graph of the transition of the amount of refrigerant. The description will be made assuming that a point of an amount of refrigerant of 0% is a thermo-OFF state, a point of an amount of refrigerant of 10% is a thermo-ON state, a point of an amount of refrigerant of 20% is an off-state where the rotation of the indoor fan 73 stops, and a point of an amount of refrigerant of 30% is an on-state where the indoor fan 73 rotates.
Remote controllers or the like of the first to third indoor units 7A, 7B, and 7C are operated to start operation of the respective indoor units 7. As illustrated in Fig. 2(a), regarding the first indoor unit 7A, the thermo-ON state continues due to the suction temperature of indoor air below a set target temperature, and also the indoor fan 73 of the indoor unit 7A is in the on-state, and the amount of refrigerant in the indoor unit 7A is stable around 40%.
As illustrated in Fig. 2(b) and Fig. 2(c), when the suction temperature of indoor air reaches the set target temperature at time t=2 (minutes), the second indoor unit 7B and the third indoor unit 7C are switched from a thermo-ON state to a thermo-OFF state, however, the rotation of the respective indoor fans 73 continues, and accordingly the amounts of refrigerant increase. At time t=5, when three minutes has passed since the indoor units 7B and 7C enter the thermo-OFF state, the respective indoor fans 73 are switched from the on-state to the off-state and accordingly the amounts of refrigerant decrease. At time t=10, when five minutes has passed since the respective indoor fans 73 enter the off-state, the amounts of refrigerant increase again since the indoor fans 73 are switched from the off-state to the on-state. At time t=13, when three minutes has passed since the respective indoor fans 73 enter the on-state, the indoor fans 73 are switched to the off-state, and the amounts of refrigerant decrease to be stable around 40%.
As described above, the intermittent operation is traditionally performed based on the preset on-period and off-period, timings when the indoor fans 73 in the thermo-OFF state are switched to the thermo-ON state on the assumption of the worst possible condition are made same in the second indoor unit 7B and the third indoor unit 7C. Thereby, an increase and a decrease in amount of refrigerant in the indoor units 7 change in the same manner, and thus, the transition of the amount of refrigerant necessary for all the indoor units 7 is as shown in Fig. 2(d). On the calculation of the added values, the maximum of the necessary amount of refrigerant is approximately 240%, taking the necessary amount of refrigerant for one indoor unit as a base of 100%.
Fig. 3 illustrates the transition of the thermo-ON/OFF states of three indoor units 7 (black triangle marks), the ON/OFF states of indoor fans 73 (black round marks), an amount of refrigerant estimated depending on the thermo-ON/OFF states and the ON/OFF states of the indoor fans 73 (black rhombus marks). In Fig. 3, as in Fig. 2, Fig. 3(a) illustrates the transition of an amount of refrigerant in a first indoor unit 7A, Fig. 3(b) illustrates the transition of an amount of refrigerant in a second indoor unit 7B, and Fig. 3(c) illustrates the transition of an amount of refrigerant in a third indoor unit 7C. Fig. 3(d) illustrates the transition of total amounts of refrigerant in all the indoor units 7A, 7B, and 7C. As in Fig. 2, the thermo-ON/OFF states and the ON/OFF states of the indoor fans 73 are shown overlapping on the graph of the transition of the amount of refrigerant. A description will be given of operation of the packaged air conditioning system 1 according to the present embodiment with reference to Fig. 1 to Fig. 3, illustrating a case where an on-period is three minutes and an off-period is five minutes in the intermittent operation.
Remote controllers or the like of the first to third indoor units 7A, 7B, and 7C are operated to start operation of the respective indoor units 7. As illustrated in Fig. 3(a), regarding the first indoor unit 7A, the thermo-ON state continues due to the suction temperature of indoor air below a set target temperature, and also the indoor fan 73 of the first indoor unit 7A is in the on-state, and the amount of refrigerant in the first indoor unit 7A is stable around 40%.
If there is an indoor unit(s) (for example, the second indoor unit 7B and the third indoor unit 7C) that has entered a thermo-OFF state as a result of the suction temperature of the indoor air reaching a target set temperature, signals indicating "the second indoor unit 7B is in a thermo-OFF state" and "the third indoor unit 7C is in a thermo-OFF state" are output to the control unit 41.
Upon detecting existence of the indoor unit 7 that has entered the thermo-OFF state, the control unit 41 reads out information on a model capacity of the indoor unit 7 having entered the thermo-OFF state and allocates the indoor unit 7 to a group appropriately. It is assumed here that the control unit 41 sets two groups. In a first group, upon detecting that the first one of the indoor units 7 has entered a thermo-OFF state, the control unit 41 continues the rotation of an indoor fan 73 for a predetermined time and then suspends the rotation of the indoor fan 73 for a predetermined time. In a second group, upon detecting that the first one of the indoor units 7 has entered a thermo-OFF state, the control unit 41 suspends the rotation of an indoor fan 73 for the predetermined time and then rotates the indoor fan 73 for the predetermined time after the end of the rotation of the indoor fan 73 (on-period) in the other group.
The groups are formed so that total model capacities of the indoor units 7 that are in the thermo-OFF state in the groups become approximately equal to each other. As illustrated in Fig. 3, if there are two indoor units, that is, the second indoor unit 7B and the third indoor unit 7C that have entered the thermo-OFF state at time t=2 (minutes), the control unit 41 determines to assign the second indoor unit 7B to the first group and assign the third indoor unit 7C to the second group. The control unit 41 assigns the two indoor units 7 that have entered the thermo-OFF state simultaneously to different groups.
At time t=2, the control unit 41 outputs, to the second indoor unit 7B assigned to the first group, a command for setting the rotation of the indoor fan 73 to the on-state. The second indoor unit 7B sets the indoor fan 73 to the on-state according to the command. Thereby, the second indoor unit 7B is in the thermo-OFF state and the indoor fan 73 is in the on-state, and therefore, the amount of refrigerant increases. Also, the control unit 41 outputs, to the third indoor unit 7C assigned to the second group, a command for setting the rotation of the indoor fan 73 to the off-state. The third indoor unit 7C sets the indoor fan 73 to the off-state according to the command.
At time t=5 when a predetermined time (for example, three minutes) has passed, the control unit 41 outputs, to the second indoor unit 7B in which the rotation of the indoor fan 73 is in the on-state, a command for suspending the rotation of the indoor fan 73 to set the indoor fan 73 to the off-state. On receiving the command, the second indoor unit 7B switches the indoor fan 73 from the on-state to the off-state. Thereby, the second indoor unit 7B is in the thermo-OFF state and the indoor fan 73 is also in the off-state, and therefore, the amount of refrigerant in the second indoor unit 7B gradually decreases and settles into around 40%.
At time t=6, since the indoor fan 73 of the second indoor unit 7B in the first group is in the off-state, the control unit 41 outputs, to the third indoor unit 7C in the second group, a command for setting the indoor fan 73 to the on-state. On receiving the command, the third indoor unit 7C switches the indoor fan 73 from the off-state to the on-state. Thereby, the third indoor unit 7C is in the thermo-OFF state and the indoor fan 73 is in the on-state, and therefore, the amount of refrigerant increases.
At time t=9 when a predetermined time (for example, three minutes) has passed, the control unit 41 outputs, to the third indoor unit 7C in which the rotation of the indoor fan 73 is in the on-state, a command for setting the indoor fan 73 to the off-state. On receiving the command, the third indoor unit 7C switches the indoor fan 73 from the on-state to the off-state. Thereby, the third indoor unit 7C is in the thermo-OFF state and the indoor fan 73 is also in the off-state, and therefore, the amount of refrigerant in the third indoor unit 7C gradually decreases and settles into around 40%.
At time t=10, since the indoor fan 73 of the third indoor unit 7C in the second group is in the off-state, the control unit 41 outputs, to the second indoor unit 7B in the first group, a command for setting the indoor fan 73 to the on-state. On receiving the command, the second indoor unit 7B switches the indoor fan 73 from the off-state to the on-state. Thereby, the amount of refrigerant in the second indoor unit 7B gradually increases. Thereafter, the control unit 41 performs ON/OFF control in the same way so that on-periods of the indoor fans 73 of the indoor units 7 belonging to the respective groups do not overlap with each other.
Afterwards, an indoor unit 7 that enters a thermo-OFF state (for example, the indoor unit 7A) is sequentially assigned to one of the first group and the second group with a smaller total model capacity of indoor units 7 in a thermo-OFF state included therein. In this way, assignment can be performed so that the total model capacities of the indoor units that are in the thermo-OFF state included in the respective groups become approximately equal to each other.
Note that even if an indoor unit 7 that has been once assigned to a group is switched from a thermo-OFF state to a thermo-ON state, information on the group to which the indoor unit 7 has been assigned previously is no longer maintained. Specifically, when the indoor unit 7 that has once entered the thermo-ON state from the thermo-OFF state is switched to the thermo-OFF state next time, it is determined that which group the indoor unit 7 is to be assigned based on the total model capacity of each group at that time (irrespective of the previous group information). In other words, since there is an indoor unit 7 in a thermo-OFF state that is to be switched to a thermo-ON state to sequentially leave the group, each total capacity is varying continuously. For this reason, when the indoor unit 7 is switched to the thermo-OFF state next time, the respective total model capacities at that time are calculated and a group to be an allocation destination is determined.
As described so far, indoor units 7 that have entered a thermo-OFF state are each assigned to different groups by the control unit 41 so that a timing for an on-period of an indoor fan 73 is varied for each group, and thereby, timings of a peak in the transition of the amount of refrigerant are different from each other as illustrated in Fig. 3(b) and Fig. 3(c). Accordingly, the transition of the amount of refrigerant necessary for the indoor units 7A, 7B and 7C is as illustrated in Fig. 3(d), where the added value is, if calculated, around 180% (= 40% in the first indoor unit 7A + 60% in the second indoor unit 7B + 80% in the third indoor unit 7C) at the most.
Even when a plurality of indoor units 7 simultaneously have entered a thermo-OFF state, the indoor units 7 are assigned to a plurality of groups among which timings of ON/OFF operation of the indoor fan 73 are different to make variations in fluctuation of the amount of refrigerant. Thus, the necessary amount of refrigerant can be suppressed.
If at least one of the first group and the second group has a total model capacity of indoor units exceeding an average (e.g., 50%) obtained by dividing a total model capacity of all the indoor units connected to the same outdoor unit 2 (i.e., 100%) by the number of groups (e.g., two groups), the indoor unit 7 with a smallest model capacity in the group that has the total capacity of the indoor units exceeding 50% is preferably shifted to the other group. As a result of this, each of the total model capacities of the groups can be approximated to the substantial equalization.
Alternatively, if one indoor unit 7 has a model capacity exceeding an average (e.g., 50%) obtained by dividing the total capacity of all the indoor units (i.e., 100%) by the number of groups (e.g., two groups), the groups are preferably divided into one group to which the indoor unit 7 with the model capacity exceeding 50% relative to the total capacity of all the indoor units is to be assigned, and the other group to which indoor units 7 in the thermo-OFF state other than the relevant indoor unit 7 are to be assigned.
In the present embodiment, although the case has been illustrated where timings to switch ON/OFF in the intermittent operation of the indoor fans 73 in the respective groups are prescribed in the control unit 41, the present invention is not limited to this. For example, through an input device or the like from an outside, ON/OFF timings in the respective groups may be varied as appropriate.
The control unit 41 according to the aforementioned embodiment may be configured so that all of or a part of the processes described above are performed by software provided separately. In this case, the control unit 41 includes a CPU (Central Processing Unit), a main storage unit such as a RAM (Random Access Memory), and a computer-readable recording medium in which a program (control program, for example) for realizing all of or a part of the above processes is recorded. The CPU reads the program recorded in the recording medium and executes information processing and computing processes, thereby realizing similar processes to those performed by the control unit 41 described above.
Examples of the computer-readable recording medium referred to herein include a magnetic disk, a magnetooptical disk, a CD (Compact Disk)-ROM (Read Only Memory), a DVD (Digital Versatile Disk)-ROM, and a semiconductor memory. Alternatively, this computer program may be distributed to a computer over a communication line and the computer to which the computer program is distributed may execute the program.
As described so far, according to the control unit (control device) 41, the control method, the control program, and the packaged air conditioning system 1 including the control device in the present embodiment, in a thermo-OFF mode during a heating operation, if an indoor fan 73 of an indoor unit 7 performs an intermittent operation, a plurality of groups of the indoor units for matching timings for the intermittent operation are formed, the timing for the intermittent operation is shifted for each group, and assignment of the indoor units to the groups is controlled so that total model capacities of the indoor units that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.
In this way, to the groups which have different timings for the intermittent operation, the indoor units are assigned so that each total model capacity of the indoor units becomes equal. Accordingly, the amounts of refrigerant accumulating in a heat exchanger of the indoor unit during the on-period of the indoor fan 73 in the thermo-OFF mode during a heating operation are averaged, whereby the necessary amount of refrigerant can be minimized. Therefore, a necessary amount of refrigerant can be reduced, and the receiver capacity can also be reduced as a result.

[Modification]

In the above embodiment, although the case has been illustrated where two groups are set for an intermittent operation of indoor fans 73, the number of groups is not limited to this. Three or more groups may be set. A description will be given of operation of the packaged air conditioning system 1 with the reference to Fig. 4, illustrating a case where three groups, that is, a first group, a second group, and a third group are set. In the present modification, a case will be illustrated where the indoor fans 73 perform an intermittent operation with an on-period of three minutes and an off-period of six minutes.
Remote controllers or the like corresponding to the three respective indoor units 7 are operated to start operation of the indoor units 7. An indoor unit 7 that has entered the thermo-OFF state first as a result of the suction temperature of indoor air reaching the set target temperature is assigned to the first group, and an indoor fan 73 thereof is in the on-state for three minutes. At this time, an indoor fan 73 of each of the indoor unit 7 belonging to the second group and the indoor unit 7 belonging to the third group is in the off-state. The indoor unit 7 that has entered the thermo-OFF state next is assigned to the second group, and the indoor unit 7 that has entered the thermo-OFF state after next is assigned to the third group. Afterwards, an indoor unit 7 that enters a thermo-OFF state is sequentially assigned to a group with a smallest total model capacity of the indoor units 7 that are included therein and are in the thermo-OFF state, of three groups, that is, the first group, the second group, and the third group.
The indoor fan 73 of the indoor unit 7 in the first group is switched from the on-state to the off-state at time t=3 (minutes), and then the off-state is maintained for six minutes (i.e., until time t=9 (minutes)). The indoor fan 73 of the indoor unit 7 in the second group is switched from the off-state to the on-state at time t=3, continues the on-state until time t=6, and is switched to the off-state at time t=6. The indoor fan 73 of the indoor unit 7 in the third group is switched from the off-state to the on-state at time t=6, at which the indoor fans 73 of the indoor units 7 both in the first group and the second group are in the off-state, continues the on-state until time t=9, and is switched to the off-state at time t=9.
Afterwards, the indoor units 7 belonging to the first to third groups are controlled so that the ON/OFF states of the indoor fans 73 thereof are each switched in the above described manner and the on-periods when the indoor fans 73 are in the on-state do not overlap one another.
If at least one of the first group, the second group and the third group has a total model capacity of indoor units exceeding an average (e.g., 33%) obtained by dividing a total model capacity of all the indoor units connected to the same outdoor unit 2 (i.e., 100%) by the number of groups (e.g., three groups), the indoor unit 7 with a smallest model capacity in the group that has the total capacity of the indoor units exceeding 33% is preferably shifted to another group. As a result of this, each of the total model capacities of the groups can be approximated to the substantial equalization.
Alternatively, if one indoor unit 7 has a model capacity exceeding an average (e.g., 33%) obtained by dividing the total capacity of all the indoor units (i.e., 100%) by the number of groups (e.g., three groups), the groups are preferably divided into a group to which the indoor unit 7 with the model capacity exceeding 33% relative to the total capacity of all the indoor units is to be assigned, and the other groups to which indoor units 7 in the thermo-OFF state other than the relevant indoor unit 7 are to be assigned.

{Reference Signs List}

1: packaged air conditioning system
2: outdoor unit
7, 7A, 7B: indoor unit
27: receiver
41: control unit (control device)

Claims

A control device for controlling operation of a packaged air conditioning system in which a plurality of indoor units are connected to an outdoor unit, wherein
during a heating operation, if an indoor fan of each of the indoor units performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, the control device forms a plurality of groups of the indoor units for matching timings for the intermittent operation of the respective indoor units, shifts the timing for the intermittent operation for each group, and controls assignment of the indoor units to the groups so that total model capacities of the indoor units that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.
The control device according to claim 1, wherein the control device sets a different timing of an on-period in the intermittent operation for each of the groups so that the on-periods of the groups do not overlap with each other.
The control device according to claim 1 or 2, wherein the control device assigns the indoor unit that is switched from a thermo-ON state to a thermo-OFF state to the group with a smallest total model capacity of the indoor units, of the plurality of groups.
The control device according to any one of claims 1 to 3, wherein if there is a group in which the total model capacity of the indoor units is equal to or larger than a predetermined ratio relative to the total model capacities of all the groups, the control device assigns the indoor unit with a smallest model capacity in the group with the total model capacity equal to or larger than the predetermined ratio to the group with the smallest total model capacity.
The control device according to any one of claims 1 to 4, wherein if one of the indoor units has a model capacity equal to or larger than a predetermined ratio relative to the total model capacities of all the group, the control device assigns another indoor unit than the indoor unit with the model capacity equal to or larger than the predetermined ratio to a group that is different from the group that includes the indoor unit with the model capacity equal to or larger than the predetermined ratio.
A packaged air conditioning system comprising the control device according to any one of claims 1 to 5.
A control method for controlling operation of a packaged air conditioning system in which a plurality of indoor units are connected to an outdoor unit, comprising:
during a heating operation, if an indoor fan of each of the indoor units performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, forming a plurality of groups of the indoor units for matching timings for the intermittent operation of the respective indoor units; shifting the timing for the intermittent operation for each group; and controlling assignment of the indoor units to the groups so that total model capacities of the indoor units that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.
A control program for controlling operation of a packaged air conditioning system in which a plurality of indoor units are connected to an outdoor unit, the program causing a computer to, during a heating operation, if an indoor fan of each of the indoor units performs an intermittent operation for repeating ON/OFF operations to stop for a predetermined time after rotating for a predetermined time at a time at which a thermostat is turned off, form a plurality of groups of the indoor units for matching timings for the intermittent operation of the respective indoor units, shift the timing for the intermittent operation for each group, and control assignment of the indoor units to the groups so that total model capacities of the indoor units that are included in the respective groups and are in a thermo-OFF state become approximately equal to each other.