JP4383472B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner and relates to control of an indoor unit.

  Generally, an air conditioner is known in which a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve are connected in parallel to an outdoor unit having a compressor and an outdoor heat exchanger.

  In this type, when any one of the indoor units is stopped, the refrigerant may sleep in the stopped indoor unit. Conventionally, in order to collect the refrigerant sleeping in the indoor heat exchanger of this indoor unit in the outdoor unit, the stop time of the stopped indoor unit is measured, and after the fixed time has elapsed, The indoor expansion valve of the indoor unit is opened by a predetermined opening, and the refrigerant sleeping in the indoor heat exchanger is collected by the outdoor unit.

  However, in the conventional configuration, there is a problem in that the outdoor unit runs out of gas when a large amount of refrigerant has slept before a certain period of time for collecting the refrigerant that has slept in the indoor heat exchanger.

  Also, if the capacity of the heat exchanger of the stopped indoor unit is large, if the refrigerant that has fallen into it is trying to return the refrigerant to the outdoor unit at once by opening the indoor expansion valve, the amount of refrigerant that has fallen down is large. There is a problem that defects such as back occur.

  Therefore, the object of the present invention is to solve the problems of the conventional technology described above, prevent a large amount of refrigerant from sleeping in a heat exchanger having a capacity larger than a certain amount, prevent gas shortage, and operate stably. An object of the present invention is to provide an air conditioner capable of maintaining the above.

According to the first aspect of the present invention, a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve are added to one or a plurality of outdoor units having a compressor, an outdoor heat exchanger, and an outdoor expansion valve. In the air conditioner connected in parallel, one or more prediction means for predicting the occurrence of gas shortage provided in at least one of the one or more outdoor units, and the one or more predictions during heating operation When at least one of the means predicts the occurrence of gas shortage and there is a stopped indoor unit, the indoor expansion valve of the stopped indoor unit is opened at a predetermined interval every predetermined cycle. In accordance with the state of the indoor expansion valve of the stopped indoor unit, the control means for performing a control to recover the refrigerant that has been opened and closed step by step, and collects the refrigerant that has stagnation in the indoor heat exchanger of the stopped indoor unit, Adjusting means for adjusting the predetermined opening unit of the control means; Characterized by comprising a.
According to this configuration, when a gas shortage is predicted by the prediction unit, the indoor expansion valve is opened / closed by a predetermined opening unit by the control unit at predetermined intervals, and the refrigerant stagnation is eliminated. The opening unit of the indoor expansion valve is adjusted by the adjusting means in accordance with the state of the indoor expansion valve.
Thereby, the stagnation of the refrigerant is eliminated and the occurrence of liquid back is suppressed.

According to a second aspect of the present invention, the adjustment means is configured such that the predetermined opening degree unit when the indoor expansion valve of the stopped indoor unit is closed is smaller than the predetermined opening unit when the indoor unit is opened. It is characterized by adjusting as follows.
According to this configuration, the predetermined opening unit for closing the indoor expansion valve of the stopped indoor unit is adjusted to be smaller than the predetermined opening unit for opening. Thereby, the increase in the resistance with respect to the refrigerant | coolant inside piping can be suppressed, and the stagnation of a refrigerant | coolant can be prevented.

According to a third aspect of the present invention, when the adjustment means closes the indoor expansion valve of the stopped indoor unit, the predetermined opening when the opening of the indoor expansion valve is smaller than a predetermined opening is provided. The degree unit is adjusted to be smaller than the predetermined opening unit when the opening of the indoor expansion valve is larger than the predetermined opening.
According to this configuration, when closing the indoor expansion valve, the predetermined opening unit when the opening of the indoor expansion valve is smaller than the predetermined opening is set to be larger than the predetermined opening. It is adjusted to be smaller than a predetermined opening degree unit. Thereby, even if it is a case where generation | occurrence | production of gas shortage is not estimated, it can prevent that a refrigerant | coolant sleeps.

According to a fourth aspect of the present invention, the adjusting means adjusts the predetermined opening degree unit so as to be within a range of a predetermined upper limit value and a lower limit value.
According to this configuration, the predetermined opening degree unit is adjusted so as to be within the range between the predetermined upper limit value and the predetermined lower limit value. Thereby, it can prevent that the opening degree of a valve changes rapidly.

According to a fifth aspect of the present invention, when the out-of-gas is not predicted in all of the one or the plurality of predicting means, the adjusting means is configured to open the indoor expansion valve and the valve opening degree of the outdoor expansion valve. The predetermined opening degree unit is adjusted on the basis of the difference.
According to this configuration, when the gas shortage is not predicted, the predetermined opening degree unit is adjusted based on the difference between the opening degrees of the indoor expansion valve and the outdoor expansion valve. As a result, the valve opening degree of the outdoor expansion valve is reduced, the valve is stabilized in a state where the absolute value of the valve opening degree of the outdoor expansion valve is increased, and unnecessary refrigerant can be prevented from flowing into the stopped indoor unit.

  By the means for opening the valve opening of the indoor expansion valve of the indoor unit having a certain capacity that is stopped during heating operation, it is possible to prevent the refrigerant from sleeping in the indoor heat exchanger and to prevent gas shortage. As a result, stable operation is maintained.

  Even if the refrigerant stagnates in the indoor heat exchanger of the stopped indoor unit, when the refrigerant was recovered, the upper limit was set for the increase valve opening of the indoor expansion valve of the indoor unit. Since the refrigerant is not collected in the outdoor unit at a time, problems such as liquid back can be prevented and stable operation can be maintained.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In FIG. 1, 1a and 1b indicate outdoor units, and 3a, 3b, and 3c indicate indoor units. The outdoor unit 1a includes a compressor 5a driven by a gas engine, a check valve 7a, a four-way valve 9a, an outdoor heat exchanger 13a, an outdoor expansion valve 17a, a liquid valve 19a, a bypass valve 21a, and an accumulator 23a. And is composed of. In addition, 11a shows the outdoor heat exchanger refrigerant | coolant exit | outlet temperature sensor provided in the pipe line by the side where a refrigerant | coolant flows out from the outdoor heat exchanger 13a at the time of heating operation, 15a shows outdoor heat exchanger 13a at the time of heating operation 1 shows an outdoor heat exchanger refrigerant inlet temperature sensor provided in a pipe line on the refrigerant flow side, and 25a shows a fan of the outdoor heat exchanger 13a. Since the outdoor unit 1b is the same as the outdoor unit 1a including the following configuration, the description thereof is omitted.

  The indoor unit 3a includes an indoor heat exchanger 27a and an indoor expansion valve 29a. Reference numeral 31a denotes an indoor heat exchanger refrigerant outlet temperature sensor provided in a conduit on the side from which the refrigerant flows out of the indoor heat exchanger 27a during the cooling operation, and 33a denotes a refrigerant in the indoor heat exchanger 27a during the cooling operation. The indoor heat exchanger refrigerant | coolant inlet_port | entrance temperature sensor provided in the pipe line of the side into which is flowed is shown. Since the indoor units 3b and 3c are the same as the indoor unit 3a including the following configurations, the description thereof is omitted. From the indoor units 3a, 3b, and 3c, an inter-unit pipe including a gas pipe 35 and a liquid pipe 37 extends, and the outdoor units 1a and 1b are connected in parallel to the inter-unit pipe.

  In the above configuration, during the cooling operation, the refrigerant from the compressors 5a and 5b is supplied with check valves 7a and 7b, four-way valves 9a and 9b, outdoor heat exchangers 13a and 13b, outdoor, as indicated by dotted arrows in FIG. The gas flows out into the liquid pipe 37 through the expansion valves 17a and 17b, enters the respective indoor units 3a, 3b and 3c, flows in the order of the indoor expansion valves 29a, 29b and 29c, and the indoor heat exchangers 27a, 27b and 27c. 35 and then returned to the compressors 5a and 5b via the four-way valves 9a and 9b and the accumulators 23a and 23b.

  Further, during the heating operation, the refrigerant from the compressors 5a and 5b flows into the gas pipe 35 through the check valves 7a and 7b and the four-way valves 9a and 9b as shown by solid arrows in FIG. Enters the machines 3a, 3b, 3c, flows in the order of the indoor heat exchangers 27a, 27b, 27c, the indoor expansion valves 29a, 29b, 29c and flows out to the liquid pipe 37, and further, the outdoor expansion valves 17a, 17b, the outdoor heat exchanger 13a, 13b, four-way valves 9a, 9b, and accumulators 23a, 23b are returned to the compressors 5a, 5b.

Each outdoor unit 1a, 1b is provided with an outdoor control device 39a, 39b for individually controlling each outdoor unit 1a, 1b. Each indoor unit 3a, 3b, 3c includes each indoor unit 3a, Indoor control devices 41a, 41b and 41c for individually controlling 3b and 3c are provided. And the centralized control apparatus 43 which controls these outdoor units 1a and 1b and the indoor units 3a, 3b, and 3c collectively is provided. This centralized control device 43 monitors the outdoor control devices 39a and 39b and the indoor control devices 41a, 41b and 41c through control lines, and transmits and receives control signals.
In this embodiment, the capacity of the indoor heat exchanger 27c of the indoor unit 3c is larger than the capacity of the indoor heat exchangers 27a and 27b of the other indoor units 3a and 3b. In this embodiment, the capacity of the indoor heat exchangers 27a and 27b is 14 kW, and the indoor heat exchanger 27c is 22.4 kW.

  By the way, since the indoor thermal expansion valve 29 of the stopped indoor unit 3 is closed during the heating operation, conventionally, there has been a case where the refrigerant stagnates in the indoor heat exchanger 27 of the stopped indoor unit 3. When the stagnation refrigerant is collected in the outdoor unit 1, the central control device 43 or the indoor control device 41 of each indoor unit 3 measures the stop time of the indoor unit 3 that is stopped, and the measured stop time When a certain time has elapsed, the indoor expansion valve 29 was opened, and the refrigerant sleeping in the indoor heat exchanger 27 was recovered in the outdoor unit 1 in operation. However, when the indoor heat exchanger 27 of the stopped indoor unit 3 has a large capacity, if the refrigerant falls into the indoor heat exchanger 27 having a large capacity, the refrigerant of the outdoor unit in operation When a situation occurs in which the gas flow is insufficient and the exhausted refrigerant is recovered in the indoor heat exchanger 27 having a large capacity, if the recovered refrigerant is recovered in the outdoor unit 1 at a time, the liquid back As a result, problems such as the occurrence of problems such as driving became unstable.

  For this reason, in this embodiment, a means for predicting the out of gas is provided so that the refrigerant does not stagnate in the indoor heat exchanger 27 having a capacity larger than a certain value, and when the out of gas is predicted, the indoor unit 3 is provided with control means for opening the indoor expansion valve 29 and returning the refrigerant to the operating outdoor unit. Moreover, even if the refrigerant stagnates, the upper limit value of the number of steps for increasing the valve opening degree of the indoor expansion valve is set so that the stagnation refrigerant is not collected in the outdoor unit 1 at a time and trouble such as liquid back occurs. The control which adjusts and adjusts the valve opening degree of the indoor expansion valve 29 according to the capacity | capacitance of the indoor heat exchanger 27 of the indoor expansion valve 29 is implemented.

  The indoor unit 3 to be controlled has a capacity of the indoor heat exchanger 27 that is larger than a certain level among the stopped indoor units 3. In this embodiment, the indoor heat exchanger 27 having a capacity of 22.4 kW or more is controlled, and the indoor heat exchanger 27c is applicable.

Prior to the control for adjusting the valve opening degree of the indoor expansion valve 29 of the stopped indoor unit 3, the central control device 43 is based on data such as refrigerant pressure and refrigerant temperature of one outdoor unit 1 in operation. In order to control the entire apparatus, the outdoor unit 1 that takes in this data is selected as a reference unit.
In this embodiment, the outdoor unit 1 activated first is selected as the reference unit. As conditions for starting up first, it has been devised that the cumulative operation time is short or based on a preset priority operation order. In this embodiment, the outdoor units 1a and 1b are both operated, and the outdoor unit 1a is selected as the reference unit.

  Hereinafter, the control of adjusting the valve opening degree of the indoor expansion valve 29c of the indoor unit 3c when at least one of the indoor units 3a and 3b is operated and the indoor unit 3c is stopped will be described with reference to the flowchart of FIG. Will be described in detail.

  First, the central control device 43 determines whether the indoor unit 3 in operation is in a heating operation (S1). The control for adjusting the valve opening degree of the indoor expansion valve 29c prevents a large amount of refrigerant from sleeping in the indoor heat exchanger 27c of the indoor unit 3c that is stopped during the heating operation. Since it is the control which collects refrigerant | coolants gradually, without collect | recovering at once, it is not implemented when it is not judged that it is heating operation.

  When it is determined that the heating operation is performed, the outdoor control devices 39a and 39b of the outdoor units 1a and 1b individually detect the temperatures detected by the outdoor heat exchanger refrigerant inlet temperature sensors 15a and 15b, and the outdoor heat exchanger refrigerant. The temperature difference between the temperatures detected by the outlet temperature sensors 11a and 11b is calculated, and it is determined whether or not the refrigerant flow rate of each outdoor unit 1 is insufficient (whether or not there is a gas shortage) based on the temperature difference data. To do. That is, in this embodiment, the outdoor control devices 39a and 39b are prediction means for predicting whether or not there is a gas shortage. In this embodiment, the temperature difference for determining whether or not the gas is lacking is 10 ° C. As a result of the experiment, the temperature difference changes from 10 ° C. to about 22 ° C. according to the shortage of the refrigerant flow rate.

  When the refrigerant flow rate is satisfied, the temperature difference at the refrigerant inlet / outlet is about 2 ° C. to 7 ° C. as a result of the experiment, and the set value of the temperature difference that is normally determined to be sufficient is 0 ° C. Since it is -5 degreeC, if a temperature difference is 10 degreeC, it can be judged that generation | occurrence | production of the gas shortage of the said outdoor unit 1 is estimated.

  The outdoor control devices 39a and 39b of the outdoor units 1a and 1b, which are determined to be predicted to be out of gas in the outdoor unit 1, individually open the outdoor expansion valves 17a and 17b according to the temperature difference between the refrigerant inlets and outlets. Adjust the degree.

  Here, the centralized control device 43 monitors changes in the valve openings of the outdoor expansion valves 17a and 17b through control lines, and the gas of the outdoor unit 1 is determined from the changes in the valve openings of the outdoor expansion valves 17a and 17b. Detect that a defect is predicted to occur.

  When the central control device 43 detects that the out-of-gas occurrence of the outdoor unit 1 is predicted, the central control device 43 determines that the refrigerant has stagnated in the indoor heat exchanger 27 of the stopped indoor unit 3. When the indoor units 3b and 3c are stopped, the conventional control is performed on the indoor unit 3b because the capacity of the indoor heat exchanger 27b is smaller than a certain capacity. In this conventional control, the centralized control device 43 measures the stop time of the indoor unit 3b. When the stop time has elapsed for a certain time, the valve opening of the indoor expansion valve 29b is increased, and Collect in the outdoor unit 1 in operation. On the other hand, with respect to the indoor unit 3c, the capacity of the indoor heat exchanger 27c is larger than a certain capacity, so that control for adjusting the valve opening degree of the indoor expansion valve 29c according to the capacity of the indoor heat exchanger 27c is performed. .

  The valve opening degree of the indoor expansion valve 29c is adjusted based on the indoor expansion valve calculation coefficient X by calculating the indoor expansion valve calculation coefficient X based on the following equation 1 (S2).

  The indoor expansion valve calculation coefficient X is calculated at regular intervals by the outdoor control device 39 of the outdoor unit 1 in operation. In this embodiment, the fixed time is 30 seconds.

  Further, in Equation 1, V1 is the current outdoor expansion valve opening, V2 is the previous outdoor expansion valve opening, and V3 is the indoor unit valve opening coefficient.

  The valve opening degree of each indoor expansion valve 29 and each outdoor expansion valve 17 is adjusted by increasing or decreasing the number of steps, and this V3 is the sum of the number of steps of the indoor expansion valve opening degree during stop and the indoor unit expansion valve during operation. This is the total of the number of steps of the opening multiplied by a constant.

  Next, it is determined whether or not the indoor expansion valve calculation coefficient X is larger than 20 (S3). If it is not determined that the value is greater than 20, it is determined whether the indoor expansion valve calculation coefficient X is less than -20 (S4).

  In S3 and S4, when the indoor expansion valve calculation coefficient X is not greater than 20 and not smaller than −20, that is, when the indoor expansion valve calculation coefficient X is −20 <X <20, the valve of the outdoor expansion valve 17 The opening degree is not increased from the valve opening degree at the time of the previous detection (30 seconds before), and the control for adjusting the valve opening degree of the indoor expansion valve 29c of the stopped indoor unit 3c is not executed.

  In S3 and S4, when the indoor expansion valve calculation coefficient X is larger than 20 or smaller than −20, control for adjusting the valve opening degree of the indoor expansion valve 29c of the stopped indoor unit 3c is executed, and the indoor expansion is performed. The valve opening correction reference amount δSTEP_1 is calculated by the following equation 2:

  In the calculation formula number 2, n indicates the number of indoor units 3 including the indoor heat exchanger 27 having a capacity of 22.4 kW or more.

  This outdoor expansion valve opening correction reference amount δSTEP_ 1 is calculated at regular intervals by the outdoor control device 39 of the outdoor unit 1 during operation. That is, the indoor expansion valve opening correction reference amount δSTEP_ 1 is calculated based on the indoor expansion valve calculation coefficient X calculated every 30 seconds. The outdoor unit 1 in operation communicates the calculated value of the indoor expansion valve opening correction reference amount δSTEP_ 1 to the central control device 43 via the control line.

  When the central control device 43 receives the indoor expansion valve opening correction reference amount δSTEP_1 from each outdoor unit 1 in operation, the central control device 43 receives the indoor expansion valve opening correction reference amount from the outdoor unit 1 (outdoor unit 1a) selected as the reference unit. The indoor expansion valve opening of each indoor unit 3 is adjusted based on δSTEP_1 (hereinafter referred to as the selected indoor expansion valve opening correction reference amount δSTEP ').

  First, the centralized controller 43 inputs 0 to i indicating the operation number of the indoor unit 3 (S6), and the indoor heat exchanger 27 of the indoor unit 3 is set for each indoor unit 3 in the order of decreasing operation number i. It is determined whether or not the capacity is greater than 22.4 kW (S7). When the capacity of the indoor heat exchanger 27 of the indoor unit (i) is not larger than 22.4 kW, the valve opening degree of the indoor expansion valve 29 of this indoor unit (i) is constant as before. Increased at one time after time.

  When the capacity of the indoor heat exchanger 27 of the indoor unit (i) is larger than 22.4 kW, it is first determined whether or not the indoor unit (i) is in operation (S8). When the indoor unit (i) is in operation, the valve opening degree of the indoor expansion valve 29 is controlled according to the operation status.

  If the indoor unit (i) is not in operation, it is determined whether or not the value of the selected indoor expansion valve opening correction reference amount δSTEP 'is smaller than 0 (S9).

  The central control device 43 determines whether or not the value of the selected indoor expansion valve opening correction reference amount δSTEP 'is smaller than 0. If the value is smaller than 0, the valve opening degree of the outdoor expansion valve 17 of the reference machine is determined. When it is smaller than the previous time (30 seconds before), that is, when the outdoor control device 39 of the reference machine is predicted to be out of gas although it is predicted that the reference machine has run out of gas, it is not less than 0. When the valve opening degree of the outdoor expansion valve 17 of the reference machine becomes larger than the previous time (30 seconds before), that is, the reference controller outdoor control device 39 predicts that the reference machine is out of gas and is out of gas. This is the case when it is determined that there is.

  If it is determined that the value of the selected indoor expansion valve opening correction reference amount δSTEP 'is smaller than 0, it is determined whether or not the current value of the indoor expansion valve opening STEP (i) is smaller than 350. (S10).

  If it is not determined that the current value of the indoor expansion valve opening STEP (i) is smaller than 350, the indoor expansion valve opening correction amount coefficient K is set to 1.0 (S11), and the current indoor expansion valve opening STEP STEP When it is determined that the value of (i) is smaller than 350, the indoor expansion valve opening correction amount coefficient K is set to 0.5 (S12), and the indoor expansion valve opening correction reference amount δSTEP 'is selected. By multiplying the expansion valve opening correction amount coefficient K, the indoor expansion valve opening correction amount δSTEP (i) is calculated (S15).

  In S9, the value of δSTEP 'is negative, and it is determined that the occurrence of gas shortage is predicted, but it is not out of gas. If this value of δSTEP' is negative, the indoor expansion valve opening calculated in S15 The correction amount δSTEP (i) is negative. In S10 to S12, when it is not determined that the current value of the indoor expansion valve opening STEP (i) is smaller than 350, the indoor expansion valve opening correction amount coefficient K is 1.0, and the current indoor expansion valve opening correction amount coefficient K is 1.0. When it is determined that the value of the expansion valve opening STEP (i) is smaller than 350, the indoor expansion valve opening correction amount coefficient K is 0.5. Therefore, when the occurrence of a gas shortage is predicted but not a gas shortage, the current valve opening degree of the indoor expansion valve 29 of the indoor unit 3 to be controlled is decreased and the current indoor expansion valve is opened. When the value of degree STEP (i) is larger than 350, the amount of decrease in the valve opening is large, and when the value of the current indoor expansion valve opening STEP (i) is smaller than 350, the valve opening is decreased. The amount becomes smaller. That is, even when the occurrence of a gas shortage in the outdoor unit 1 during operation is not predicted, the opening degree of the indoor expansion valve 29 of the stopped indoor unit 3 is set in order to prevent the refrigerant flow shortage in a preventive manner. Increase according to the current valve opening.

  In S9, if it is not determined that the value of the selected indoor expansion valve opening correction reference amount δSTEP 'is smaller than 0, the following is based on the value of the compressor discharge pressure sensor (not shown) of the reference machine. Saturation temperature Ts of the refrigerant (in this embodiment, refrigerant R22 is used) calculated by the equation 3 shown below, the outlet temperature during the heating operation of the heat exchanger 27 of the indoor unit (i), That is, it is determined whether or not the temperature difference from the temperature E1 (i) detected by the heat exchanger outlet temperature sensor 33 is greater than 2 ° C (S13). It is determined that the refrigerant has stagnated in the indoor heat exchanger 27 of i), and the indoor expansion valve opening correction amount coefficient K is set to 1.5 (S14). As a result, the indoor expansion valve opening correction amount δSTEP (i) of the indoor expansion valve 29 of the indoor unit (i) can be increased, and the refrigerant can be quickly recovered. When it is not determined that the temperature difference between the saturation temperature Ts and the outlet temperature E1 (i) during the heating operation of the heat exchanger 27 is greater than 2 ° C., the indoor expansion valve opening correction amount coefficient K is set to 1.0. (S11).

  Next, in S15, it is determined whether or not the calculated value of the indoor expansion valve opening correction amount δSTEP (i) is greater than 60 (S16). When it is determined that the value of the indoor expansion valve opening correction amount δSTEP (i) is larger than 60, the value of the indoor expansion valve opening correction amount δSTEP (i) is set to 60 (S19), and the indoor expansion valve opening is set. If the value of the degree correction amount δSTEP (i) is not determined to be greater than 60, it is determined whether or not the value of the new indoor expansion valve opening correction amount δSTEP (i) is less than −30 (S17). . When it is determined that the value of the indoor expansion valve opening correction amount δSTEP (i) is smaller than −30, the value of the indoor expansion valve opening correction amount δSTEP (i) is set to −30 (S18). The indoor expansion valve opening correction amount δSTEP (i) is added to the indoor expansion valve opening STEP (i), and a new indoor expansion valve opening of the indoor unit (i) is obtained (S20).

  Then, when adjusting the valve opening degree of the indoor expansion valve 29 to a new indoor expansion valve opening degree, when the valve opening degree is decreased, the valve is adjusted as compared with the case where the valve opening degree is increased. Doubled the time. For this reason, the resistance with respect to the refrigerant | coolant inside piping does not increase, and a refrigerant | coolant is hard to sleep again.

  Then, 1 is added to the operation number i (S21), and the operation proceeds to the adjustment of the opening degree of the indoor expansion valve 29 of the other indoor unit (i), and the number obtained by adding 1 to this operation number is the number of indoor units. It is determined whether or not they are equal (S22), and the adjustment of the opening degree of the indoor expansion valve 29 of the other indoor unit (i) is repeatedly executed until the number obtained by adding 1 to the operation number becomes equal to the number of indoor units. If it is determined that they are equal, this control ends.

After this S22 is completed, the process returns to S1 again, and is repeatedly executed while any indoor unit 3 of the air conditioner is in operation, and the refrigerant stagnates in the indoor heat exchanger 27 of the stopped indoor unit 3. It is possible to prevent the occurrence of gas shortage.
That is, in this embodiment, when the refrigerant has stagnated in the indoor heat exchanger 27c of the indoor unit 3c, the upper limit of the increase in the indoor expansion valve opening correction amount of the indoor expansion valve 29c is set to 60 steps. Since the valve opening degree is adjusted and the control of opening the valve of the indoor expansion valve 29c is repeatedly performed as necessary, the stagnation refrigerant is gradually recovered in the outdoor unit 1 in operation.

  Further, when there is no change in the opening of the outdoor expansion valve 17a, that is, when there is no gas shortage and stable operation, the difference between the absolute value of the opening of the outdoor expansion valve 17 and the absolute value of the opening of the indoor expansion valve 29 is different. Based on the above, the opening degree of the indoor expansion valve 29 is adjusted. The reason for this is that when the refrigerant flow rate is sufficient, that is, when the gas shortage is completely eliminated, the valve opening degree of the outdoor expansion valve 17 decreases and the absolute value of the valve opening degree of the indoor expansion valve 29 increases. This is to prevent the state from being stabilized. This prevents unnecessary refrigerant from flowing into the stopped indoor unit and avoids inefficient operation.

  This embodiment has the following effects.

  In S7, the indoor unit 3 provided with the indoor heat exchanger 27 having a capacity of the indoor heat exchanger 27 larger than a certain value (22.4 kW) is selected, and in S9, the stopped indoor unit 3 among the indoor units 3 is selected. In S10, the indoor expansion valve opening correction amount δSTEP (i) is calculated in S15 while referring to the current valve opening of the indoor expansion valve 29 of the stopped indoor unit 3, and S16 to S19. Thus, when the value of the indoor expansion valve opening correction amount δSTEP (i) is −30 <δSTEP (i) <60, the value is uniformly 60 when the value is larger than a certain amount (60 steps). If it is smaller than the amount (-30 steps), it is uniformly -30, and in S20, it is added to the current indoor expansion valve opening STEP (i), so the indoor heat exchanger 27 having a capacity larger than a certain value is installed. Increase opening degree of indoor expansion valve opening degree of indoor unit 3 provided, Each small opening, the upper limit value and the lower limit value is set, yet, an air conditioner is the control is repeatedly executed during operation.

  For this reason, the valve opening degree of the indoor expansion valve 29 of the indoor unit 3 is gradually adjusted, so that it is possible to prevent a large amount of refrigerant from sleeping in the indoor heat exchanger 27 having a capacity larger than a certain amount, and the refrigerant flow rate is increased. An insufficient gas shortage state can be prevented.

  Further, even when a large amount of refrigerant has fallen into the indoor heat exchanger 27 for a fixed time (30 seconds) from the previous adjustment of the valve opening degree of the indoor expansion valve 29, the indoor temperature is set to 60 steps as an upper limit at a time. Since the valve opening of the expansion valve does not increase, the refrigerant that has fallen into the indoor heat exchanger 27 of the indoor unit 3 is not collected in the outdoor unit 1 that is operating at a time, and there is a problem such as liquid back. And stable operation is maintained.

  Furthermore, conventionally, in the air conditioner including the compressors 5a and 5b driven by the gas engine, a plurality of indoor units 3 including a large-capacity indoor heat exchanger 27 exceeding the capacity of the outdoor heat exchangers 13a and 13b of the outdoor unit 1 are provided. It has been difficult to configure the device by connecting the base for the following reasons. The reason is that there is a large amount of refrigerant sleeping in the indoor heat exchanger 27 of the indoor unit 3, and there is a problem such as liquid back when the sleeping refrigerant is collected in the outdoor unit 1 that is in operation. In the air conditioner provided in the drive source, there are many parameters to be controlled compared to those provided with the electric motor in the drive source, and the operation is likely to be unstable. However, by performing control to prevent a large amount of refrigerant from sleeping in the indoor heat exchanger 27 having a capacity larger than a certain level according to the present invention, the outdoor unit 1 in which a large amount of refrigerant that has fallen at a time is operating. No trouble such as liquid back occurs. For this reason, a plurality of indoor units 3 including large-capacity indoor heat exchangers 27 exceeding the capacity of the outdoor heat exchangers 13a and 13b of the outdoor unit 1 are connected, and an air conditioner including a gas engine as a drive source is configured. It becomes possible to do.

It is a block diagram which shows one Example of the air conditioning apparatus by this invention. It is a flowchart figure for adjusting the valve opening degree of an indoor expansion valve.

Explanation of symbols

1, 1a, 1b Outdoor unit 3, 3a, 3b, 3c Indoor unit 17, 17a, 17b Outdoor expansion valve 27, 27a, 27b Indoor heat exchanger 29, 29a, 29b Indoor expansion valve 39, 39a, 39b Outdoor unit control device 41, 41a, 41b, 41c Indoor unit control device 43 Central control device

Claims (5)

In an air conditioner in which a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve are connected in parallel to one or a plurality of outdoor units having a compressor, an outdoor heat exchanger, and an outdoor expansion valve ,
One or more prediction means for predicting the occurrence of gas shortage provided in at least one of the one or more outdoor units;
When the occurrence of a gas shortage is predicted by at least one of the one or more prediction means during heating operation, and there is a stopped indoor unit, the indoor expansion valve of the stopped indoor unit is set. A control means for performing a control for recovering the refrigerant trapped in the indoor heat exchanger of the stopped indoor unit by opening and closing step by step in a predetermined opening unit for each predetermined period;
Adjusting means for adjusting the predetermined opening degree of the control means according to the state of the indoor expansion valve of the stopped indoor unit;
An air conditioner comprising: The air conditioner according to claim 1,
The adjustment means adjusts the predetermined opening unit when the indoor expansion valve of the stopped indoor unit is closed to be smaller than the predetermined opening unit when the indoor expansion valve is opened. Harmony device. In the air conditioning apparatus according to claim 1 or 2,
When the indoor expansion valve of the stopped indoor unit is closed, the adjusting means sets the predetermined opening unit when the opening of the indoor expansion valve is smaller than a predetermined opening to open the indoor expansion valve. The air conditioner is adjusted so that the degree is smaller than the predetermined opening unit when the degree is larger than the predetermined opening. The air conditioning apparatus according to any one of claims 1 to 3,
The said adjustment means adjusts so that the said predetermined opening degree unit may be settled in the range of a predetermined | prescribed upper limit and predetermined | prescribed lower limit, The air conditioning apparatus characterized by the above-mentioned. In the air conditioning apparatus according to any one of claims 1 to 4,
When the out-of-gas is not predicted in all of the one or the plurality of predicting means, the adjusting means is configured to open the predetermined opening based on a difference in valve opening between the indoor expansion valve and the outdoor expansion valve. An air conditioner characterized by adjusting a degree unit.

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