JP2007163106A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize error in estimating a refrigerant amount caused by difference in solubility to oil, of a refrigerant by solving stagnation of refrigerant to refrigerating machine oil in a compressing mechanism. <P>SOLUTION: This air conditioner 1 comprises the refrigerant circuit 7, refrigerant stagnation judging means 8a-8c, and operation control device 6a-6c. The refrigerant circuit is a circuit including heat source units 2a-2c, refrigerant communication piping 4, 5, heat source-side expansion valves 31a, 31b, and use-side expansion valves 29a-29c, use units 3a, 3b. The heat source units and the use units are connected with the refrigerant communication piping. The heat source units have compressing mechanisms 21a-21c and the heat source-side heat exchangers 24a-24c. The refrigerant stagnation judging means can judge a situation of refrigerant stagnation in the compressing mechanism. The operation control device performs a refrigerant stagnation releasing operation for releasing refrigerant stagnation when the refrigerant stagnation in the compressing mechanism is detected before the refrigerant amount determining operation for determining the refrigerant amount in the circuit is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a refrigerant circuit of an air conditioner and an air conditioner including the refrigerant circuit.

As a refrigerant leakage detection device of a conventional refrigeration apparatus, there is one disclosed in Patent Document 1. In this refrigerant leak detection device, the condensed refrigerant temperature and the evaporated refrigerant temperature adjusting means adjust the condensed refrigerant temperature and the evaporated refrigerant temperature to constant values, and compare the output signal of the discharge refrigerant temperature detector with the set value. The refrigerant leak detection operation for detecting the refrigerant leak in the refrigeration cycle is performed by the temperature difference calculating means for calculating the temperature difference. Therefore, by adjusting the condensing refrigerant temperature flowing through the condenser and the evaporating refrigerant temperature flowing through the evaporator to a constant value, the discharge refrigerant temperature under an appropriate refrigerant amount is set as a set value, and the set value and the discharge refrigerant temperature The output signal of the detector is compared, and if it is lower than the set value, it is determined that refrigerant leakage has not occurred, and if it is higher than the set value, it is determined that refrigerant leaks.
Japanese Patent Application Laid-Open No. 11-211292

However, in the technique of Patent Document 1, since the amount of refrigerant that dissolves in the refrigerating machine oil in the compression mechanism increases at low outside air temperature, there is a risk that the prediction error of the refrigerant amount increases. In particular, when the internal oil temperature is low immediately after the start of the compressor, or when only some of the compressors are driven during the refrigerant leak detection operation while having a plurality of compressors, the refrigerant leak detection error increases.
An object of the present invention is to eliminate the stagnation of the refrigerant with respect to the refrigeration oil in the compression mechanism, and to minimize the prediction error of the refrigerant amount due to the difference in the solubility of the refrigerant in the oil.

  An air conditioner according to a first aspect of the present invention includes a refrigerant circuit, a refrigerant stagnation determining means, and an operation control device. The refrigerant circuit is a circuit including a heat source unit, a refrigerant communication pipe, an expansion mechanism, and a utilization unit. The heat source unit includes a compression mechanism and a heat source side heat exchanger. A heat source unit is connected to the refrigerant communication pipe. The usage unit has a usage-side heat exchanger and is connected to the refrigerant communication pipe. The refrigerant stagnation determining means can determine whether or not the refrigerant has stagnation in the compression mechanism. When performing the refrigerant amount determination operation for determining the refrigerant amount in the refrigerant circuit, the operation control device determines that the refrigerant stagnation determination unit determines in advance that the refrigerant has stagnation in the compression mechanism. Perform refrigerant stagnation elimination operation to eliminate.

In this air conditioner, when the refrigerant amount determination operation is performed, it is determined in advance by the refrigerant stagnation determination means whether or not the refrigerant has stagnation in the refrigerating machine oil in the compression mechanism. Then, when the refrigerant stagnation determining means determines that the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism, the operation control device performs the refrigerant stagnation elimination operation.
Therefore, in this air conditioner, the refrigerant amount determination operation can be performed after eliminating the stagnation of the refrigerant with respect to the refrigerating machine oil in the compression mechanism. For this reason, in the refrigerant quantity determination operation, the refrigerant quantity dissolved in the refrigeration machine oil in the compression mechanism can be reduced as much as possible, and the prediction error of the refrigerant quantity can be reduced. As a result, the refrigerant stagnation with respect to the refrigerating machine oil in the compression mechanism can be eliminated during the refrigerant quantity determination operation, so that a more accurate refrigerant quantity determination operation can be performed.

An air conditioner according to a second aspect is the air conditioner according to the first aspect, wherein the refrigerant stagnation determining means makes a determination based on the temperature in the compression mechanism.
In this air conditioner, the determination by the refrigerant stagnation determination means is made based on the temperature in the compression mechanism. When the temperature in the compression mechanism is low, the refrigerant easily stagnates in the refrigeration oil. Therefore, when the temperature in the compression mechanism is low, it can be determined that the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism. For this reason, based on the temperature in the compression mechanism, it is possible to determine whether or not the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism.

An air conditioner according to a third aspect of the present invention is the air conditioner according to the first aspect of the present invention, wherein the refrigerant stagnation determining means makes a determination based on the outside air temperature.
In this air conditioner, the determination by the refrigerant stagnation determination means is made based on the outside air temperature. When the temperature in the compression mechanism is low, the refrigerant easily stagnates in the refrigeration oil. Therefore, since the outside air temperature can be measured, the temperature in the compression mechanism can be predicted. For this reason, when it can be predicted that the temperature in the compression mechanism is low, it is possible to determine that the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism. Thereby, it is possible to determine whether or not the refrigerant has stagnated in the refrigeration machine oil in the compression mechanism.

An air conditioner according to a fourth aspect of the present invention is the air conditioner according to the first aspect of the present invention, wherein the refrigerant stagnation determining means makes a determination based on weather information.
In this air conditioner, the determination by the refrigerant stagnation determination means is made based on weather information obtained via a network connected to the refrigerant stagnation determination means. Therefore, the outside air temperature can be acquired from the weather information, and the temperature in the compression mechanism can be predicted. For this reason, when it can be predicted that the temperature in the compression mechanism is low, it is possible to determine that the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism. Thereby, it is possible to determine whether or not the refrigerant has stagnated in the refrigeration machine oil in the compression mechanism.

An air conditioner according to a fifth aspect of the present invention is the air conditioner according to the first aspect of the present invention, wherein the refrigerant stagnation determining means makes a determination based on a refrigerant stagnation period in which the refrigerant is predicted to easily stagnate in the compression mechanism.
In this air conditioner, the determination by the refrigerant stagnation determination means is made based on a preset period. When the temperature in the compression mechanism is low, the refrigerant easily stagnates in the refrigeration oil. This determination is made by providing a period during which the temperature in the compression mechanism is predicted to be low.
Therefore, the user can predict the stagnation of the refrigerant without measuring the temperature in the compression mechanism by setting a period during which the temperature in the compression mechanism is predicted to be low. Thereby, it is possible to determine whether or not the refrigerant has stagnated in the refrigeration machine oil in the compression mechanism. Moreover, since it is not necessary to install a temperature sensor or the like, the production cost can be reduced.

An air conditioner according to a sixth aspect of the present invention is the air conditioner according to any of the first to fifth aspects of the invention, wherein the operation control unit performs control for driving the compression mechanism for a first predetermined time as the refrigerant stagnation elimination operation. Do.
In this air conditioner, the refrigerant stagnation elimination operation is a warm-up operation by driving the compressor for a first predetermined time. Therefore, in this refrigerant stagnation elimination operation, the inside of the compression mechanism can be warmed by operating the compressor for the first predetermined time. For this reason, it becomes possible to eliminate the stagnation of the refrigerant with respect to the refrigerating machine oil in the compression mechanism.

An air conditioner according to a seventh aspect of the present invention is the air conditioner according to any one of the first to sixth aspects, wherein there are a plurality of heat source units.
In this air conditioner, there are a plurality of heat source units. Therefore, since the heat source units in the system can be driven by rotating each unit for a certain period of time, the load is not biased to one unit even at a low load, and the life of the entire system can be extended.

  An air conditioner according to an eighth aspect of the present invention is the air conditioner according to any one of the first to seventh aspects, wherein the compression mechanism has a plurality of compressors.

  In this air conditioner, the compression mechanism has a plurality of compressors. Therefore, since the capacity of the compression mechanism can be changed by controlling the number of compressors, even when the operating load of the utilization unit is reduced, it becomes possible to continue the operation of all the heat source units. Retention of refrigerant and oil can be prevented as much as possible. Further, even if one of the plurality of compressors breaks down, the remaining compressors can cope. For this reason, complete stop of air conditioning can be avoided.

An air conditioner according to a ninth aspect is the air conditioner according to the eighth aspect, wherein the refrigerant stagnation elimination operation is an operation for driving at least a compressor that is not driven during the refrigerant amount determination operation.
In this air conditioner, when there are a plurality of compressors, the compressor driven by the refrigerant amount determination can be sufficiently warmed during the refrigerant amount determination operation. Drive the compressor not driven by. Therefore, it is not necessary to drive all the compressors, so that the energy used can be reduced. Moreover, the time required for the refrigerant stagnation elimination operation can be shortened.

An air conditioner according to a tenth aspect of the present invention is the air conditioner according to the eighth aspect of the present invention, wherein the refrigerant stagnation elimination operation is carried out in order by the operation control device to drive all the compressors one by one at intervals of a second predetermined time. It is driving to be performed.
In this air conditioner, when there are a plurality of compressors, all the compressors are rotated one by one and driven for a second predetermined time. In the cooling stagnation elimination operation, since the cooling operation is performed at a low outside air temperature, it is difficult to act on all the compressors at a time because of a low load. For this reason, it is possible to drive all the compressors in advance by operating them one by one for the second predetermined time.

An air conditioner according to an eleventh aspect of the invention is the air conditioner according to the first aspect of the invention, further comprising a heater that warms the compression mechanism. The refrigerant stagnation elimination operation is an operation in which the compression mechanism is warmed by the heater.
In this air conditioner, the refrigerant stagnation elimination operation is performed by warming the compression mechanism with a heater. Therefore, it is possible to eliminate the stagnation of the refrigerant without driving the compressor. For this reason, since it is not necessary to drive the compressor during the refrigerant stagnation elimination operation, the drive time of the compressor can be shortened and the life of the compressor can be extended.

An air conditioner according to a twelfth aspect of the present invention is the air conditioner according to any of the first to eleventh aspects of the present invention, wherein the operation control device further performs an oil return operation immediately after the refrigerant stagnation elimination operation. The oil return operation is an operation for returning the oil accumulated in the refrigerant circuit into the compression mechanism.
In this air conditioner, an oil return operation is further performed after the refrigerant stagnation elimination operation. Therefore, by further performing the oil return operation, the oil accumulated in the refrigerant circuit can be returned to the compression mechanism. For this reason, more accurate refrigerant quantity determination operation is possible.

An air conditioner according to a thirteenth aspect of the present invention is the air conditioner according to the twelfth aspect of the present invention, wherein the oil return operation is an operation for controlling the refrigerant flow rate in the pipe of the refrigerant flowing through the refrigerant circuit to be equal to or higher than a predetermined flow rate. .
In this air conditioner, the oil return operation is an operation for controlling the refrigerant flow rate in the pipe to be equal to or higher than a predetermined flow rate. Therefore, it is possible to reliably return the oil accumulated in the refrigerant circuit into the compression mechanism. For this reason, more accurate refrigerant quantity determination operation is possible.

  In the air conditioner according to the first aspect of the present invention, the refrigerant amount determination operation can be performed after eliminating the stagnation of the refrigerant with respect to the refrigerating machine oil in the compression mechanism. For this reason, in the refrigerant quantity determination operation, the refrigerant quantity dissolved in the refrigeration machine oil in the compression mechanism can be reduced as much as possible, and the prediction error of the refrigerant quantity can be reduced. As a result, the refrigerant stagnation with respect to the refrigerating machine oil in the compression mechanism can be eliminated during the refrigerant quantity determination operation, so that a more accurate refrigerant quantity determination operation can be performed.

In the air conditioner according to the second aspect of the present invention, when the temperature in the compression mechanism is low, it is possible to determine that the refrigerant is stagnant with respect to the refrigerating machine oil in the compression mechanism. For this reason, based on the temperature in the compression mechanism, it is possible to determine whether or not the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism.
In the air conditioner according to the third aspect of the invention, the temperature inside the compression mechanism can be predicted because the outside air temperature can be measured. For this reason, when it can be predicted that the temperature in the compression mechanism is low, it is possible to determine that the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism. Thereby, it is possible to determine whether or not the refrigerant has stagnated in the refrigeration machine oil in the compression mechanism.

  In the air conditioning apparatus according to the fourth aspect of the invention, the outside air temperature can be acquired from the weather information, and the temperature in the compression mechanism can be predicted. For this reason, when it can be predicted that the temperature in the compression mechanism is low, it is possible to determine that the refrigerant has stagnated in the refrigerating machine oil in the compression mechanism. Thereby, it is possible to determine whether or not the refrigerant has stagnated in the refrigeration machine oil in the compression mechanism.

  In the air conditioning apparatus according to the fifth aspect of the invention, the user can predict the stagnation of the refrigerant without measuring the temperature in the compression mechanism by setting a period during which the temperature in the compression mechanism is predicted to be low. It becomes. Thereby, it is possible to determine whether or not the refrigerant has stagnated in the refrigeration machine oil in the compression mechanism. Moreover, since it is not necessary to install a temperature sensor or the like, the production cost can be reduced.

In the air conditioner according to the sixth aspect of the present invention, in the refrigerant stagnation elimination operation, the inside of the compression mechanism can be warmed by operating the compressor for the first predetermined time. For this reason, it becomes possible to eliminate the stagnation of the refrigerant with respect to the refrigerating machine oil in the compression mechanism.
In the air conditioner according to the seventh aspect of the invention, the heat source unit in the system can be driven by rotating for one unit at a time for a certain period of time, so that the load is not biased to one unit even at low loads, thereby extending the life of the entire system. Can do.

  In the air conditioner according to the eighth aspect of the invention, since the capacity of the compression mechanism can be changed by controlling the number of compressors, all the heat source units can be continuously operated even when the operating load of the utilization unit is reduced. This makes it possible to prevent the accumulation of refrigerant and oil in the refrigerant circuit as much as possible. Further, even if one of the plurality of compressors breaks down, the remaining compressors can cope. For this reason, complete stop of air conditioning can be avoided.

In the air conditioner according to the ninth aspect of the present invention, it is not necessary to drive all the compressors, so that the energy used can be reduced. Moreover, the time required for the refrigerant stagnation elimination operation can be shortened.
In the air conditioning apparatus according to the tenth aspect of the invention, it is possible to drive all the compressors in advance by operating them one by one for the second predetermined time.

In the air conditioner according to the eleventh aspect of the present invention, it is possible to eliminate the refrigerant stagnation without driving the compressor. For this reason, since it is not necessary to drive the compressor during the refrigerant stagnation elimination operation, the drive time of the compressor can be shortened and the life of the compressor can be extended.
In the air conditioner according to the twelfth aspect of the present invention, it is possible to return the oil accumulated in the refrigerant circuit to the compression mechanism by further performing the oil return operation. For this reason, more accurate refrigerant quantity determination operation is possible.

  In the air conditioner according to the thirteenth aspect of the present invention, it is possible to reliably return the oil accumulated in the refrigerant circuit into the compression mechanism. For this reason, more accurate refrigerant quantity determination operation is possible.

(1) Configuration of Air Conditioner FIG. 1 is a schematic refrigerant circuit diagram of the air conditioner 1 according to the first embodiment of the present invention. The air conditioner 1 is used for air conditioning of a building or the like, and includes a plurality of (in this embodiment, three) air-cooled heat source units 2a to 2c and a large number of utilization units 3a, 3b,. .. Are configured to be connected in parallel to the refrigerant liquid communication pipe 4 and the refrigerant gas communication pipe 5, respectively. Here, only two units 3a and 3b are shown. Each of the plurality of heat source units 2a to 2c includes one variable capacity compressor 22a to 22c and a plurality (two in this embodiment) of constant capacity compressors 27a to 27c, 28a to 28c. The compression mechanism 21a-21c is provided.

  The usage units 3a, 3b,... Are mainly composed of usage-side expansion valves 31a, 31b,..., Usage-side heat exchangers 32a, 32b,. It is configured. In the present embodiment, the use side expansion valves 31a, 31b,... Are connected to the refrigerant liquid connection pipes of the use side heat exchangers 32a, 32b,. This is an electric expansion valve connected to the 4th side (hereinafter referred to as the liquid side). In the present embodiment, the use side heat exchangers 32a, 32b,... Are cross fin tube type heat exchangers, and are devices for exchanging heat with indoor air. In the present embodiment, the utilization units 3a, 3b,... Include an indoor fan (not shown) for taking in and sending out indoor air into the unit, and the indoor air and utilization side heat exchanger 32a. , 32b,... Can exchange heat with the refrigerant flowing through them.

  The heat source units 2a to 2c mainly include compression mechanisms 21a to 21c, four-way switching valves 23a to 23c, heat source side heat exchangers 24a to 24c, liquid side closing valves 25a to 25c, and gas side closing, respectively. It consists of valves 26a to 26c, heat source side expansion valves 29a to 29c, and piping connecting them. In the present embodiment, the heat source side expansion valves 29a to 29c adjust the refrigerant pressure, adjust the flow rate of the refrigerant, and the like, so that the refrigerant liquid communication pipe 4 side (hereinafter referred to as the liquid side) of the heat source side expansion valves 29a to 29c. It is an electric expansion valve connected to. The compression mechanisms 21a to 21c include variable capacity compressors 22a to 22c, two constant capacity compressors 27a to 27c, 28a to 28c, and an oil separator (not shown).

The compressors 22a to 22c, 27a to 27c, and 28a to 28c are devices for compressing the sucked refrigerant gas. In this embodiment, the variable capacity type 1 that can change the operation capacity by inverter control. One compressor and two compressors with constant capacity.
The four-way switching valves 23a to 23c are valves for switching the direction of the refrigerant flow when switching between the cooling operation and the heating operation. During the cooling operation, the four-way switching valves 23a to 23c are connected to the compression mechanisms 21a to 21c and the heat source side heat exchangers 24a to 24c. The refrigerant gas communication pipe 5 side (hereinafter referred to as the gas side) is connected and the suction side of the compression mechanisms 21a to 21c and the refrigerant gas communication pipe 5 are connected (the solid lines of the four-way switching valves 23a to 23c in FIG. 1). In the heating operation, the outlets of the compression mechanisms 21a to 21c and the refrigerant gas communication pipe 5 are connected and the suction sides of the compression mechanisms 21a to 21c and the gas sides of the heat source side heat exchangers 24a to 24c are connected. It is possible (see the broken lines of the four-way switching valves 23a-23c in FIG. 1).

  In the present embodiment, the heat source side heat exchangers 24a to 24c are cross fin tube type heat exchangers, and are devices for exchanging heat with a refrigerant using air as a heat source. In the present embodiment, the heat source units 2a to 2c include an outdoor fan (not shown) for taking in and sending outdoor air into the unit, and flows through the outdoor air and the heat source side heat exchangers 24a to 24c. It is possible to exchange heat with the refrigerant.

  The liquid side closing valves 25a to 25c and the gas side closing valves 26a to 26c of the heat source units 2a to 2c are connected in parallel to the refrigerant liquid communication pipe 4 and the refrigerant gas communication pipe 5, respectively. The refrigerant liquid communication pipe 4 includes the liquid side of the use side heat exchangers 32a, 32b,... Of the use units 3a, 3b,... And the liquid side of the heat source side heat exchangers 24a to 24c of the heat source units 2a to 2c. Is connected. The refrigerant gas communication pipe 5 is between the gas side of the use side heat exchangers 32a, 32b,... Of the use units 3a, 3b,... And the four-way switching valves 23a-23c of the heat source units 2a-2c. Connected.

  The air conditioner 1 further includes refrigerant stagnation determining means 8a to 8c and operation control devices 6a to 6c. The refrigerant stagnation determination means 8a to 8c determine whether or not the refrigerant has stagnation in the compression mechanisms 21a to 21c. When the operation control devices 6a to 6c perform the refrigerant amount determination operation for determining the refrigerant amount in the refrigerant circuit 7, if the refrigerant is already sleeping in the compression mechanisms 21a to 21c, the operation control devices 6a to 6c cancel the refrigerant stagnation. Perform the refrigerant stagnation elimination operation. In the present embodiment, the refrigerant stagnation determining means and the operation control devices 6a to 6c are incorporated in the heat source units 2a to 2c. Then, it is possible to perform the operation control as described above using only the operation control device (here 6a) of the heat source unit (here 2a) set as the master unit. Then, the operation control device (here 6b, 6c) of the heat source unit (here 2a, 2b) set as the other slave unit is the parent of the operation state of the device such as the compression mechanism and the detection data of various sensors. It is possible to transmit the power to the operation control device 6a of the machine, or to perform an operation and stop command to a device such as a compression mechanism by a command from the operation control device 6a of the parent machine. Here, temperature sensors 61a to 61c (see FIG. 1) are provided, the outside air temperature is measured by this temperature sensor, and the temperature data is transmitted to the operation control device 6a of the master unit. Then, the operation control device 6a determines whether or not to perform the refrigerant stagnation elimination operation.

(2) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 is demonstrated using FIG.
<Normal operation>
(Cooling operation)
First, the cooling operation will be described. During the cooling operation, in all the heat source units 2a to 2c, the four-way switching valves 23a to 23c are in the state indicated by the solid line in FIG. 1, that is, the discharge side of each compression mechanism 21a to 21c is the heat source side heat exchanger 24a to 24c. And the suction side of each compression mechanism 21a to 21c is connected to the gas side of the use side heat exchangers 32a, 32b,... . Further, the liquid side closing valves 25a to 25c and the gas side closing valves 26a to 26c are opened, and the opening degrees of the use side expansion valves 31a, 31b,... Are adjusted so as to depressurize the refrigerant.

  In the state of the refrigerant circuit 7 of the air conditioner 1, outdoor fans (not shown) of the heat source units 2a to 2c, indoor fans (not shown) of the utilization units 3a, 3b,... And the compression mechanisms 21a. When 21 to 21c is started, the refrigerant gas is sucked into the compression mechanisms 21a to 21c and compressed, and then sent to the heat source side heat exchangers 24a to 24c via the four-way switching valves 23a to 23c, so that the outside air Heat is exchanged and condensed. The condensed refrigerant liquid is merged into the refrigerant liquid communication pipe 4 and sent to the use units 3a, 3b,. And the refrigerant | coolant liquid sent to utilization unit 3a, 3b, ... is pressure-reduced by utilization side expansion valve 31a, 31b, ..., and indoors by utilization side heat exchanger 32a, 32b, ... Evaporates by heat exchange with air. The evaporated refrigerant gas is sent to the heat source units 2 a to 2 c through the refrigerant gas communication pipe 5. The refrigerant gas flowing through the refrigerant gas communication pipe 5 passes through the four-way switching valves 23a to 23c of the heat source units 2a to 2c, and is again sucked into the compression mechanisms 21a to 21c. In this way, the cooling operation is performed.

(Heating operation)
Next, the heating operation will be described. During the heating operation, in all the heat source units 2a to 2c, the four-way switching valves 23a to 23c are in the state indicated by the broken lines in FIG. 1, that is, the discharge sides of the compression mechanisms 21a to 21c are connected via the refrigerant gas communication pipe 5. Are connected to the gas side of the use side heat exchangers 32a, 32b,... And the suction side of each compression mechanism 21a to 21c is connected to the gas side of the heat source side heat exchangers 24a to 24c. . Further, the liquid side closing valves 25a to 25c and the gas side closing valves 26a to 26c are opened, and the opening degrees of the heat source side expansion valves 29a to 29c are adjusted so as to depressurize the refrigerant.

  In the state of the refrigerant circuit 7 of the air conditioner 1, outdoor fans (not shown) of the heat source units 2a to 2c, indoor fans (not shown) of the use units 3a, 3b,. When 21a-21c is started, the refrigerant gas is sucked into the compression mechanisms 21a-21c and compressed, and then is supplied to the refrigerant gas communication pipe 5 via the four-way switching valves 23a-23c of the heat source units 2a-2c. They are merged and sent to the usage units 3a, 3b,. And the refrigerant gas sent to utilization unit 3a, 3b, ... is condensed by exchanging heat with indoor air by utilization side heat exchanger 32a, 32b, .... The condensed refrigerant liquid joins the refrigerant liquid communication pipe 4 via the use side expansion valves 31a, 31b,... And is sent to the heat source units 2a to 2c side. The refrigerant liquid flowing through the refrigerant liquid communication pipe 4 is evaporated by exchanging heat with the outside air in the heat source side heat exchangers 24a to 24c of the heat source units 2a to 2c. The evaporated refrigerant gas is again sucked into the compression mechanisms 21a to 21c via the four-way switching valves 23a to 23c of the heat source units 2a to 2c. In this way, the heating operation is performed.

<Refrigerant amount judgment operation>
Next, the refrigerant quantity determination operation will be described. The refrigerant quantity determination operation includes a refrigerant leakage detection operation and an automatic refrigerant charging operation.
(Refrigerant leak detection operation)
A refrigerant leakage detection operation, which is one of the refrigerant quantity determination operations, will be described with reference to FIGS. 1 and 2. Here, FIG. 2 is a flowchart at the time of the refrigerant leak detection operation.

During cooling operation or heating operation in normal operation, switch to the refrigerant leakage detection operation, which is one of the refrigerant amount determination operations, periodically (for example, once every month, when load processing is not required in the air-conditioned space) An example will be described in which it is detected whether or not the refrigerant in the refrigerant circuit 7 has leaked to the outside due to an unexpected cause.
First, in step S1, the refrigerant amount determination preparation operation is performed before the refrigerant leakage detection operation. This refrigerant quantity determination preparation operation will be described later.

Next, in step S2, it is determined whether or not a certain time (for example, one month) has elapsed in a normal operation such as the cooling operation or the heating operation, and when a certain time has elapsed in the normal operation. Moves to the next step S2.
In step S3, when the operation in the normal operation has passed for a fixed time, the refrigerant circuit 7 is in a state where the four-way switching valves 23a to 23c of the heat source units 2a to 2c are shown by the solid line in FIG. , 3b,..., The use side expansion valves 31a, 31b,... Are opened, the compression mechanisms 21a to 21c and the outdoor fan (not shown) are activated, and the use units 3a, 3b,.・ All of these are forcibly cooled.

In step S4, the condensation pressure control by the outdoor fan, the superheat degree control by the use side expansion valves 31a, 31b,... And the evaporation pressure control by the compression mechanisms 21a to 21c are performed, and the refrigerant circulating in the refrigerant circuit 7 is controlled. The state is stabilized.
In step S5, the degree of supercooling at the outlets of the heat source side heat exchangers 24a to 24c is detected.

  In step S6, the suitability of the refrigerant quantity is determined from the value of the degree of supercooling detected in step S5. Here, when detecting the degree of supercooling in step S5, the heat source side heat exchange is performed irrespective of the form of the utilization units 3a, 3b,... And the lengths of the refrigerant liquid communication pipe 4 and the refrigerant gas communication pipe 5. Appropriateness of the amount of refrigerant filled in the refrigerant circuit 7 can be determined by the degree of supercooling of the refrigerant at the outlets of the containers 24a to 24c.

  When the amount of refrigerant to be additionally charged is small and has not reached the necessary amount of refrigerant, the amount of refrigerant in the heat source side heat exchangers 24a to 24c is small (specifically, the degree of supercooling detected in step S5). This means that the value is smaller than the degree of supercooling corresponding to the required refrigerant amount at the condensation pressure of the heat source side heat exchangers 24a to 24c.) For this reason, when the supercooling degree value detected in step S5 is substantially the same value as the target supercooling degree value (for example, the difference between the detected supercooling degree value and the target supercooling degree value is less than a predetermined value). Therefore, it is determined that there is no refrigerant leakage, and the refrigerant leakage detection operation is terminated.

On the other hand, when the supercooling degree value detected in step S5 is smaller than the target supercooling degree value (for example, the difference between the detected supercooling degree value and the target supercooling degree value is a predetermined value or more). In step S7, it is determined that a refrigerant leak has occurred, the process proceeds to step S7, and a warning display informing that the refrigerant leak has been detected is performed. Then, the refrigerant leak detection operation is terminated.
(Automatic refrigerant charging operation)
The refrigerant automatic charging operation, which is one of the refrigerant quantity determination operations, will be described with reference to FIGS. 1 and 3. Here, FIG. 3 is a flowchart at the time of the automatic refrigerant charging operation.

The refrigerant circuit 7 is configured by connecting the heat source units 2a to 2c preliminarily filled with the refrigerant and the utilization units 3a, 3b,... Via the refrigerant liquid communication pipe 4 and the refrigerant gas communication pipe 5. Later, an example in which the refrigerant circuit 7 is additionally filled with a refrigerant that is insufficient according to the lengths of the refrigerant liquid communication pipe 4 and the refrigerant gas communication pipe 5 will be described.
First, the liquid side shut-off valves 25a to 25c and the gas side shut-off valves 26a to 26c of the heat source units 2a to 2c are opened, and the refrigerant circuit 7 is filled with the refrigerant previously filled in the heat source units 2a to 2c.

  Next, a person who performs the refrigerant charging operation uses a remote controller (not shown), or a use side control unit (not shown) of the use units 3a, 3b,... And an operation control device for the heat source units 2a to 2c. When a command is issued directly to 6a to 6c to perform the automatic refrigerant charging operation, which is one of the refrigerant quantity determination operations, the automatic refrigerant charging operation is performed in the procedure from step S11 to step S14.

In step S11, a refrigerant quantity determination preparation operation is performed before the refrigerant automatic charging operation. This refrigerant quantity determination preparation operation will be described later.
In step S12, when an instruction to start the automatic refrigerant charging operation is made, the refrigerant circuit 7 is in a state where the four-way switching valves 23a to 23c of the heat source units 2a to 2c are indicated by solid lines in FIG. , 3b,..., The use side expansion valves 31a, 31b,... Are opened, the compression mechanisms 21a to 21c and the outdoor fan (not shown) are activated, and the use units 3a, 3b,.・ All of these are forcibly cooled.

In step S13, the condensation pressure control by the outdoor fan, the superheat degree control by the use side expansion valves 31a, 31b,... And the evaporation pressure control by the compression mechanisms 21a to 21c are performed, and the refrigerant circulating in the refrigerant circuit 7 is controlled. The state is stabilized.
In step S14, the degree of supercooling at the outlets of the heat source side heat exchangers 24a to 24c is detected.

In step S15, the suitability of the refrigerant amount is determined from the value of the degree of supercooling detected in step S14. Specifically, when the supercooling degree value detected in step S14 is smaller than the target supercooling degree value and the refrigerant charging is not completed, the above-described process is continued until the supercooling degree value reaches the target supercooling degree value. Steps S13 and S14 are repeated.
This automatic refrigerant charging operation is used not only for refrigerant charging during trial operation after on-site construction, but also for additional charging of refrigerant when the amount of refrigerant charged in the refrigerant circuit 7 decreases due to refrigerant leakage or the like. Is possible.

<Refrigerant amount determination preparation operation>
In the refrigerant amount determination operation, the refrigerant stagnation determination means 8a to 8c determine that the refrigerant is stagnation in the compression mechanisms 21a to 21c when the temperature detected by the temperature sensors 61a to 61c is lower than the predetermined temperature. Then, a signal indicating that the refrigerant has stagnated is sent to the operation control device 6a. The operation control device 6a that has received a signal from the refrigerant stagnation judging means 8a to 8c performs control to perform a preliminary operation (refrigerant stagnation elimination operation) so that the compressors 22a to 22c, 27a to 27c, and 28a to 28c are sufficiently warmed. ing.

  In FIG. 4, in step S21, the operation control device 6a determines whether or not the temperatures in the compression mechanisms 21a to 21c measured by the temperature sensors 61a to 61c are lower than a predetermined temperature, and the compressor temperature is the predetermined temperature. If it is lower, the process proceeds to step S22, and if not, the process proceeds to step S23. In step S22, the refrigerant stagnation elimination operation is performed and the process proceeds to step S23. In step 23, an oil return operation is performed. When the oil return operation is completed, the process proceeds to step S2 if the refrigerant amount determination operation is a refrigerant leak detection operation, and step S12 if the refrigerant amount determination operation is an automatic refrigerant charging operation. Migrate to

(Refrigerant stagnation operation)
Here, the refrigerant stagnation elimination operation in step S22 will be described. When the operation control device 6a receives signals from the refrigerant stagnation determination means 8a to 8c, it gives a command to drive all of the compression mechanisms 21a to 21c of the heat source units 2a to 2c. However, for the heat source units 2b and 2c, the operation control devices 6b and 6c of the slave units receive commands from the operation control device 6a of the master unit, and the operation control devices 6b and 6c of the slave units receive the compression mechanisms 21b and 21c. Command to drive.

  In FIG. 5, in step S31, the compressors 22a to 22c are driven, and the process proceeds to step S32. In step S32, the compressors 22a to 22c are stopped 15 minutes after step S31, the compressors 27a to 27c are driven, and the process proceeds to step S33. In step S33, the compressors 27a to 27c are stopped 15 minutes after step S32, the compressors 28a to 28c are driven, and the process proceeds to step S34. In step S34, the compressors 28a to 28c are stopped 15 minutes after step S33, and the refrigerant stagnation elimination operation is terminated.

(Oil return operation)
When the refrigerant stagnation elimination operation is completed, or when the compressor temperature is higher than the predetermined temperature in step S21, the oil return operation in step S23 is performed. Here, the oil return operation will be described with reference to FIG.
In step S41, the operation control device 6a issues a command to drive one of the compressors of the heat source units 2a to 2c (here, the compressors 22a to 22c). However, for the heat source units 2b and 2c, the operation control devices 6b and 6c of the slave units receive commands from the operation control device 6a of the master unit, and the operation control devices 6b and 6c of the slave units are in response to the compressors 22b and 22c. Command to drive. When step S41 ends, the process proceeds to step S42. In step S42, the operation control device 6a issues a command to stop after driving the compressors 22a to 22c for 5 minutes. Thereby, the oil accumulated in the refrigerant circuit 7 can be returned to the compression mechanisms 21a to 21c.

<Features>
(1)
In the air conditioner 1, when the refrigerant amount determination operation is performed, whether or not the refrigerant has stagnated in the refrigerating machine oil inside the compressors 22a to 22c, 27a to 27c, and 28a to 28c in advance by the refrigerant stagnation determining means. Is determined. When the refrigerant stagnation determining means determines that the refrigerant is sleeping in the refrigeration machine oil in the compression mechanisms 21a to 21c, the operation control device 6a performs the refrigerant stagnation elimination operation. Therefore, in this air conditioner 1, it is possible to perform the determination operation after eliminating the refrigerant accumulation in the refrigerating machine oil in the compression mechanisms 21a to 21c. For this reason, at the time of refrigerant | coolant amount determination driving | operation, the refrigerant | coolant amount melt | dissolved in the refrigeration oil in compression mechanism 21a-21c can be decreased, and the prediction error of a refrigerant | coolant amount can be made small. For this reason, in the refrigerant quantity determination operation, the refrigerant stagnation with respect to the refrigerating machine oil in the compression mechanisms 21a to 21c can be prevented, so that a highly accurate refrigerant quantity determination operation can be performed.

(2)
In the air conditioner 1, the determination by the refrigerant stagnation determination means is performed based on the temperature in the compression mechanisms 21a to 21c. For this reason, it becomes possible to measure the temperatures inside the compressors 22a to 22c, 27a to 27c, and 28a to 28c, and to determine whether or not refrigerant has stagnated in the refrigerating machine oil in the compression mechanisms 21a to 21c. Become.

(3)
In the air conditioner 1, in the refrigerant stagnation elimination operation, the compressors 22a to 22c, 27a to 27c, and 28a to 28c are warmed up for a first predetermined time. Therefore, this refrigerant stagnation elimination operation can warm the inside of the compression mechanisms 21a to 21c by operating the compressors 22a to 22c, 27a to 27c, and 28a to 28c for the first predetermined time (warm-up operation). For this reason, the inside of compression mechanism 21a-21c can fully be warmed, and the stagnation of the refrigerant | coolant with respect to the refrigerator oil in compression mechanism 21a-21c can be eliminated.

(4)
In the air conditioner 1, there are a plurality of heat source units 2a to 2c. Therefore, by rotating the heat source units 2a to 2c in the system for a certain period of time, the load is not biased to one unit even at a low load, and the life of the entire system can be extended.
(5)
In the air conditioner 1, the compression mechanisms 21a to 21c have a plurality of compressors 22a to 22c, 27a to 27c, and 28a to 28c. Therefore, since the capacity of the compression mechanisms 21a to 21c can be changed by controlling the number of the compressors 22a to 22c, 27a to 27c, and 28a to 28c, the operation load of the utilization units 3a, 3b,. Even in this case, it becomes possible to continue the operation of all the heat source units 2a to 2c, and the accumulation of refrigerant and oil in the refrigerant circuit 7 can be prevented as much as possible. Further, even if one of the plurality of compressors 22a to 22c, 27a to 27c, 28a to 28c breaks down, the remaining compressors can be handled. For this reason, complete stop of air conditioning can be avoided.

(6)
In this air conditioner 1, when there are a plurality of compressors 22a to 22c, 27a to 27c, and 28a to 28c, all the compressors 22a to 22c, 27a to 27c, and 28a to 28c are replaced one by one. Let it run for a predetermined time. Since the cooling operation is performed at a low outside air temperature during the refrigerant stagnation elimination operation, it is difficult to operate all the compressors 22a to 22c, 27a to 27c, and 28a to 28c at a time because of a low load. Therefore, it is possible to drive all the compressors 22a to 22c, 27a to 27c, and 28a to 28c in advance by operating them one by one for the second predetermined time.

(7)
In the air conditioner 1, an oil return operation is further performed after the refrigerant stagnation elimination operation. Further, in this oil return operation, control is performed so that the refrigerant flow rate in the pipe is equal to or higher than a predetermined flow rate. Therefore, the oil accumulated in the refrigerant circuit 7 can be returned by further performing the oil return operation. In addition, the oil accumulated in the refrigerant circuit 7 can be reliably returned to the compressors 22a to 22c, 27a to 27c, and 28a to 28c. For this reason, it becomes possible to operate the refrigerant quantity determination operation with higher accuracy.

<Other embodiments>
As mentioned above, although embodiment of this invention was described based on drawing, a specific structure is not restricted to these embodiment, It can change in the range which does not deviate from the summary of invention.
(A)
In the embodiment, air-cooled heat source units 2a to 2c using outside air as the heat source are used as the heat source units 2a to 2c of the air conditioner 1. However, a water-cooled or ice heat storage type heat source unit is used. Also good.

(B)
In the embodiment, the air conditioner 1 is capable of switching between cooling and heating, but may be an air conditioner dedicated to cooling or an air conditioner capable of simultaneous cooling and heating.
(C)
In the embodiment, the three heat source units 2a to 2c having the same air conditioning capability are connected in parallel. However, the heat source units having different air conditioning capabilities may be connected in parallel. The above heat source units may be connected in parallel.

(D)
In the said embodiment, although the operation control apparatuses 6a-6c are incorporated in each heat source unit 2a-2c, you may have one operation control apparatus as the whole air conditioning apparatus.
(E)
In the above embodiment, the refrigerant stagnation determining means determines whether or not the refrigerant is stagnation inside the compressors 22a to 22c, 27a to 27c, and 28a to 28c based on the outside air temperature. May be determined based on the temperature of the weather, or may be determined based on the weather information obtained from the weather information providing external server 10 using the communication line 9 such as the Internet (see FIG. 7). ), The predicted refrigerant may be determined based on the refrigerant stagnation period in which the refrigerant 22a-22c, 27a-27c, 28a-28c is likely to stagnate.

(F)
In the embodiment described above, the heat source units 2a to 2c are plural. However, the heat source units 2a to 2c are not limited to plural and may be one.
(G)
In the above-described embodiment, the three compressors 22a to 22c, 27a to 27c, and 28a to 28c are driven for 15 minutes at the time of the refrigerant stagnation elimination operation, but not limited to 15 minutes, 5, 10, 20, It may be 30 minutes. Further, it is not necessary to drive all of the compressors 22a to 22c, 27a to 27c, and 28a to 28c, as long as it is an operation that at least drives a compressor that is not driven during the refrigerant amount determination operation.

(H)
In the above-described embodiment, the refrigerant stagnation elimination operation is performed by the warm-up operation that drives the compressors 22a to 22c, 27a to 27c, and 28a to 28c to warm the compression mechanisms 21a to 21c. You may carry out by heating 21a-21c with a heater.
(I)
In the embodiment, the oil return operation is performed immediately after the refrigerant stagnation elimination operation, but the oil return operation is not necessarily performed.

  The air conditioner according to the present invention can eliminate the stagnation of the refrigerant with respect to the refrigerating machine oil in the compression mechanism before the refrigerant amount determination operation, and enables a highly accurate refrigerant amount determination operation. It is useful as a refrigerant circuit and an air conditioner equipped with the refrigerant circuit.

The schematic refrigerant circuit figure of the air conditioning apparatus which concerns on embodiment of this invention. The flowchart which shows the flow of the refrigerant | coolant leak detection driving | operation which concerns on embodiment of this invention. The flowchart which shows the flow of the refrigerant | coolant automatic charging operation which concerns on embodiment of this invention. The flowchart which shows the flow of the refrigerant | coolant determination preparation operation which concerns on embodiment of this invention. The flowchart which shows the flow of the refrigerant | coolant stagnation elimination driving which concerns on embodiment of this invention. The flowchart which shows the flow of the oil return driving | running which concerns on embodiment of this invention. The weather information acquisition network schematic diagram of the air conditioning apparatus which concerns on the modification (E) of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2a-2c Heat source unit 3a, 3b, ... Usage unit 4,5 Refrigerant communication piping 6a-6c Operation control apparatus 8a-8c Refrigerant stagnation judgment means 21a-21c Compression mechanism 22a-22c, 27a-27c, 28a to 28c Compressor 24a to 24c Heat source side heat exchanger 29a to 29c Heat source side expansion valve 31a, 31b, ... Usage side expansion valve 32a, 32c, ... Usage side heat exchanger

Claims (13)

A heat source unit (2a-2c) having a compression mechanism (21a-21c) and a heat source side heat exchanger (24a-24c), a refrigerant communication pipe (4, 5) to which the heat source unit is connected, and an expansion mechanism ( 29a to 29c, 31a, 31b,...) And use side heat exchangers (32a, 32b,...) And use units (3a, 3b,...) Connected to the refrigerant communication pipe. A refrigerant circuit (7) including:
Refrigerant stagnation determining means (8a to 8c) capable of determining whether or not the refrigerant is stagnation in the compression mechanism;
When performing the refrigerant amount determination operation for determining the refrigerant amount in the refrigerant circuit, if the refrigerant stagnation determining means determines in advance that the refrigerant is stagnation in the compression mechanism, the refrigerant stagnation is performed. An operation control device (6a to 6c) for performing the refrigerant stagnation elimination operation to be eliminated;
An air conditioner (1) comprising: The refrigerant stagnation determining means (8a to 8c) makes a determination based on the temperature in the compression mechanism (21a to 21c).
The air conditioner (1) according to claim 1. The refrigerant stagnation determining means (8a to 8c) makes a determination based on the outside air temperature.
The air conditioner (1) according to claim 1. The refrigerant stagnation determining means (8a to 8c) is connected to a network (9), acquires weather information via the network, and makes a determination based on the weather information.
The air conditioner (1) according to claim 1. The refrigerant stagnation determining means (8a to 8c) makes a determination based on a refrigerant stagnation period in which the refrigerant is predicted to easily stagnate in the compression mechanism (21a to 21c).
The air conditioner (1) according to claim 1. The operation control devices (6a to 6c) perform control for driving the compression mechanisms (21a to 21c) for a first predetermined time as the refrigerant stagnation elimination operation.
The air conditioner (1) according to any one of claims 1 to 5. There are a plurality of the heat source units (2a to 2c).
The air conditioner (1) according to any one of claims 1 to 6. The compression mechanism (21a-21c) has a plurality of compressors (22a-22c, 27a-27c, 28a-28c),
The air conditioner (1) according to any one of claims 1 to 7. The refrigerant stagnation elimination operation is an operation that drives at least a compressor that is not driven during the refrigerant amount determination operation.
The air conditioner (1) according to claim 8. In the refrigerant stagnation elimination operation, the operation control devices (6a to 6c) sequentially operate all the compressors (22a to 22c, 27a to 27c, 28a to 28c) one by one at intervals of a second predetermined time. Driving
The air conditioner (1) according to claim 8. A heater for heating the compression mechanism (21a to 21c);
The refrigerant stagnation elimination operation is an operation of heating the compression mechanism with the heater.
The air conditioner (1) according to claim 1. The operation control devices (6a to 6c) further perform an oil return operation immediately after the refrigerant stagnation elimination operation.
The air conditioner (1) according to any one of claims 1 to 11. The oil return operation is an operation for controlling the refrigerant flow rate in the pipe of the refrigerant flowing through the refrigerant circuit (7) so as to be equal to or higher than a predetermined flow rate.
The air conditioner (1) according to claim 12.

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