JPWO2016135904A1 - Refrigeration equipment - Google Patents

Abstract

The refrigeration apparatus 1 includes a heat source side unit 2 having a compressor 21, a heat source side heat exchanger 23 that functions as a condenser, and a supercooler 22, and a usage side heat exchanger that functions as a usage side expansion valve 41 and an evaporator. 42 is a refrigeration apparatus 1 having a refrigerant circuit 10 that is connected by piping and circulates a refrigerant, wherein the degree of supercooling of the refrigerant at the outlet of the supercooler 22 is increased. A refrigerant amount determination unit 3 that determines the amount of refrigerant charged in the refrigerant circuit 10 by using the temperature efficiency T of the subcooler 22 that is a value divided by the maximum temperature difference of the cooler 22 is provided. 3 obtains the operating state of the refrigeration apparatus 1 and does not determine the refrigerant amount when there is a possibility that the determination of the refrigerant amount is erroneously determined.

Description

  The present invention relates to a refrigeration apparatus that determines the amount of refrigerant in a refrigerant circuit.

  In the refrigeration apparatus, if the amount of refrigerant is excessive or insufficient, it may cause a decrease in the capacity of the refrigeration apparatus or damage to the components. Therefore, in order to prevent the occurrence of such a problem, some have a function of determining whether the amount of refrigerant filled in the refrigeration apparatus is excessive or insufficient.

  As a method for determining the refrigerant shortage in the conventional refrigeration system, for example, a temperature difference between the inlet refrigerant temperature and the outlet refrigerant temperature of the subcooler is calculated, and it is determined that the refrigerant is leaking when the temperature difference is smaller than a set value. Have been proposed (see, for example, Patent Document 1).

JP-A-9-105567

  However, since the conventional refrigeration apparatus described in Patent Document 1 uses the change in the degree of supercooling to determine the shortage of the refrigerant amount, erroneous determination is likely to occur in the refrigerant leakage determination. This is because the degree of supercooling varies greatly depending on the operating conditions of the refrigeration apparatus.

  The present invention has been made against the background of the above problems, and an object thereof is to obtain a refrigeration apparatus capable of accurately determining the amount of refrigerant.

  A refrigeration apparatus according to the present invention includes a heat source side unit having a heat source side heat exchanger and a supercooler functioning as a compressor and a condenser, and a usage side heat exchanger functioning as a usage side expansion valve and an evaporator. A refrigerating apparatus having a refrigerant circuit that is connected by piping and circulates a refrigerant, the degree of supercooling of the refrigerant at the outlet of the subcooler being a maximum temperature difference of the subcooler. A refrigerant amount determination unit that determines the amount of refrigerant charged in the refrigerant circuit using the temperature efficiency of the subcooler, which is a value obtained by dividing, and the refrigerant amount determination unit acquires the operating state of the refrigeration apparatus, If the determination of the refrigerant amount is likely to be an erroneous determination, the refrigerant amount is not determined.

  According to the refrigeration apparatus of the present invention, the refrigerant amount can be accurately determined.

It is the figure which described typically an example of the refrigerant circuit of the freezing apparatus which concerns on Embodiment 1 of this invention. It is the figure which described typically an example of the structure of the freezing apparatus which concerns on Embodiment 1 of this invention. It is an example of the ph diagram when the refrigerant | coolant amount of the refrigeration apparatus described in FIG. 1 is appropriate. FIG. 2 is an example of a ph diagram when the refrigerant amount of the refrigeration apparatus illustrated in FIG. 1 is insufficient. It is a figure explaining the relationship between the refrigerant | coolant amount of the freezing apparatus described in FIG. 1, the supercooling degree of a 1st supercooler, and the operating conditions of a freezing apparatus. FIG. 1 is a diagram for explaining an example of a temperature change of a refrigerant when the refrigerant flows in the order of a heat source side heat exchanger, a receiver, and an air supercooler when the refrigerant amount is an appropriate amount in the refrigeration apparatus illustrated in FIG. 1. It is. It is a figure explaining the relationship between the refrigerant | coolant amount of the freezing apparatus described in FIG. 1, the temperature efficiency of a 1st subcooler, and the operating conditions of a freezing apparatus. It is a figure for demonstrating not performing refrigerant | coolant amount determination according to the magnitude | size of a low pressure pressure in the refrigerant | coolant amount determination of this embodiment, when a compressor is an inverter compressor. It is a figure for demonstrating not performing refrigerant | coolant amount determination according to the magnitude | size of a low pressure pressure in the refrigerant | coolant amount determination of this embodiment, when a compressor is a constant speed compressor. It is a figure which shows an example of the relationship between the air volume of a heat source side fan, and a temperature efficiency threshold value. It is a figure explaining the relationship of the condensation temperature, the external temperature, the exit temperature of a 1st subcooler, and temperature efficiency before and behind starting of a compressor. It is a figure explaining an example of the refrigerant | coolant amount determination operation | movement of the freezing apparatus described in FIG. It is the modification 1 of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is omitted or simplified as appropriate. Moreover, the shape, size, arrangement, and the like of the configurations described in the drawings can be changed as appropriate within the scope of the present invention.

Embodiment 1 FIG.
[Refrigeration equipment]
1 is a diagram schematically illustrating an example of a refrigerant circuit of a refrigeration apparatus according to Embodiment 1 of the present invention. The refrigeration apparatus 1 illustrated in FIG. 1 performs, for example, room cooling such as a room, a warehouse, a showcase, or a refrigerator by performing a vapor compression refrigeration cycle operation. The refrigeration apparatus 1 includes, for example, one heat source side unit 2 and two usage side units 4 connected in parallel to the heat source side unit 2. The heat source side unit 2 and the use side unit 4 are connected by the liquid refrigerant extension pipe 6 and the gas refrigerant extension pipe 7, whereby the refrigerant circuit 10 for circulating the refrigerant is formed. The refrigerant charged in the refrigerant circuit 10 of this embodiment is, for example, R410A, which is an HFC mixed refrigerant. In the example of FIG. 1, one heat source side unit 2 and two usage side units 4 are described. However, two or more heat source side units 2 may be used. May be one or three or more. When there are a plurality of heat source side units 2, the capacities of the plurality of heat source side units 2 may be the same or different. When there are a plurality of usage-side units 4, the capacity of the plurality of usage-side units 4 may be the same or different. In the following description, the refrigeration apparatus 1 in which the refrigerant exchanges heat with air will be described. However, the refrigerant may be a refrigeration apparatus that exchanges heat with a fluid such as water, refrigerant, or brine.

[Usage unit]
The use side unit 4 is an indoor unit that is installed indoors, for example, and includes a use side refrigerant circuit 10 a and a use side control unit 32 that constitute a part of the refrigerant circuit 10. The use side refrigerant circuit 10 a includes a use side expansion valve 41 and a use side heat exchanger 42. The use side expansion valve 41 adjusts the flow rate of the refrigerant flowing through the use side refrigerant circuit 10a, and is configured by, for example, an electronic expansion valve or a temperature type expansion valve. The use side expansion valve 41 may be disposed in the heat source side unit 2, and in this case, the use side expansion valve 41 is, for example, the first subcooler 22 and the liquid side of the heat source side unit 2. It is arranged between the closing valve 28. The use-side heat exchanger 42 is, for example, a fin and tube heat exchanger configured to include a heat transfer tube and a large number of fins, and functions as an evaporator that evaporates the refrigerant.

  In the vicinity of the use side heat exchanger 42, a use side fan 43 that blows air to the use side heat exchanger 42 is disposed. The use-side fan 43 includes, for example, a centrifugal fan or a multi-blade fan, and is driven by a motor not shown. The use side fan 43 can adjust the amount of air blown to the use side heat exchanger 42.

[Heat source side unit]
The heat source side unit 2 includes, for example, a heat source side refrigerant circuit 10b, a first injection circuit 71, a second injection circuit 73, and a heat source side control unit 31 that constitute a part of the refrigerant circuit 10. In the following description, an example having the first injection circuit 71 and the second injection circuit 73 will be described. However, the refrigeration apparatus 1 is one of the first injection circuit 71 and the second injection circuit 73. The structure which has one side may be sufficient.

  The heat source side refrigerant circuit 10 b includes a compressor 21, a heat source side heat exchanger 23, a receiver 25, a first subcooler 22, a liquid side closing valve 28, a gas side closing valve 29, and an accumulator 24. The first injection circuit 71 branches a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side heat exchanger 42 from the heat source side refrigerant circuit 10b and returns it to the intermediate pressure part of the compressor 21. The injection amount adjusting valve 72 is included. The second injection circuit 73 branches a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side heat exchanger 42 from the heat source side refrigerant circuit 10b and flows into the suction portion of the compressor 21. And a capillary tube 74 and a solenoid valve 75 for suction injection.

  The compressor 21 is, for example, an inverter compressor that is controlled by an inverter, and can change the capacity (the amount of refrigerant sent out per unit time) by arbitrarily changing the operating frequency. The compressor 21 may be a constant speed compressor that operates at 50 Hz or 60 Hz. FIG. 1 shows an example having one compressor 21, but two or more compressors 21 are connected in parallel according to the load size of the usage-side unit 4. May be.

  The heat source side heat exchanger 23 is, for example, a fin and tube heat exchanger configured to include a heat transfer tube and a large number of fins, and functions as a condenser that condenses the refrigerant. In the vicinity of the heat source side heat exchanger 23, a heat source side fan 27 for blowing air to the heat source side heat exchanger 23 is disposed. The heat source side fan 27 blows outside air sucked from the outside of the heat source side unit 2 to the heat source side heat exchanger 23. The heat source side fan 27 includes, for example, a centrifugal fan or a multiblade fan, and is driven by a motor not shown. The heat source side fan 27 can adjust the amount of air blown to the heat source side heat exchanger 23.

  The receiver 25 is disposed between the heat source side heat exchanger 23 and the first subcooler 22 and stores excess liquid refrigerant. For example, the receiver 25 is a container for storing excess liquid refrigerant. The surplus liquid refrigerant is generated in the refrigerant circuit 10 in accordance with, for example, the size of the load on the use side unit 4, the refrigerant condensing temperature, the outside air temperature, the capacity of the compressor 21, or the like.

  The first subcooler 22 exchanges heat between the refrigerant and the air, and is formed integrally with the heat source side heat exchanger 23. That is, in the example of this embodiment, a part of the heat exchanger is configured as the heat source side heat exchanger 23, and the other part of the heat exchanger is configured as the first subcooler 22. The first subcooler 22 corresponds to the “supercooler” of the present invention. In addition, the 1st subcooler 22 and the heat source side heat exchanger 23 may be comprised separately. In that case, a fan (not shown) that blows air to the first subcooler 22 is disposed in the vicinity of the first subcooler 22.

  The liquid side closing valve 28 and the gas side closing valve 29 are constituted by valves that perform opening and closing operations such as a ball valve, an on-off valve, or an operation valve. The capillary tube 74 may be configured with a valve capable of adjusting the flow rate.

  In the example shown in FIG. 1, the inlets of the first injection circuit 71 and the second injection circuit 73 are connected between the first subcooler 22 and the liquid side shut-off valve 28, but the first injection The inlets of the circuit 71 and the second injection circuit 73 may be connected between the receiver 25 and the first subcooler 22, may be connected to the receiver 25, or may be connected to the heat source side heat exchanger 23. It may be connected between the receiver 25.

[Control unit and sensors]
Next, the control unit and sensors included in the refrigeration apparatus 1 of this embodiment will be described. The heat source side unit 2 includes a heat source side control unit 31 that controls the entire refrigeration apparatus 1. The heat source side control unit 31 includes a microcomputer and a memory. Further, the usage side unit 4 includes a usage side control unit 32 that controls the usage side unit 4. The use side control unit 32 includes a microcomputer and a memory. The use side control unit 32 and the heat source side control unit 31 can communicate and exchange control signals. For example, the use side control unit 32 receives an instruction from the heat source side control unit 31. In response, the user side unit 4 is controlled.

  The refrigeration apparatus 1 according to this embodiment includes an intake temperature sensor 33a, a discharge temperature sensor 33b, a suction outside air temperature sensor 33c, a supercooler high pressure side outlet temperature sensor 33d, a use side heat exchange inlet temperature sensor 33e, and a use side heat exchange. It includes an outlet temperature sensor 33f, a suction air temperature sensor 33g, a suction pressure sensor 34a, and a discharge pressure sensor 34b. The suction temperature sensor 33a, the discharge temperature sensor 33b, the suction outside air temperature sensor 33c, the supercooler high pressure side outlet temperature sensor 33d, the suction pressure sensor 34a, and the discharge pressure sensor 34b are disposed in the heat source side unit 2 and are controlled by the heat source. Connected to the unit 31. The use side heat exchange inlet temperature sensor 33e, the use side heat exchange outlet temperature sensor 33f, and the intake air temperature sensor 33g are provided in the use side unit 4 and connected to the use side control unit 32.

  The suction temperature sensor 33a detects the temperature of the refrigerant sucked by the compressor 21. The discharge temperature sensor 33b detects the temperature of the refrigerant discharged from the compressor 21. The subcooler high pressure side outlet temperature sensor 33d detects the temperature of the refrigerant that has passed through the first subcooler 22. The use side heat inlet temperature sensor 33e detects the evaporation temperature of the gas-liquid two-phase refrigerant flowing into the use side heat exchanger. The use-side heat exchange outlet temperature sensor 33f detects the temperature of the refrigerant that has flowed out of the use-side heat exchanger 42. The above-mentioned sensor for detecting the temperature of the refrigerant is disposed, for example, in contact with the refrigerant pipe or inserted into the refrigerant pipe, and detects the temperature of the refrigerant.

  The suction outside air temperature sensor 33c detects the ambient temperature outside the room by detecting the temperature of the air before passing through the heat source side heat exchanger 23. The intake air temperature sensor 33g detects the ambient temperature in the room where the use side heat exchanger 42 is installed by detecting the temperature of the air before passing through the use side heat exchanger 42.

  The suction pressure sensor 34 a is disposed on the suction side of the compressor 21 and detects the pressure of the refrigerant sucked into the compressor 21. The suction pressure sensor 34 a may be disposed between the gas side closing valve 29 and the compressor 21. The discharge pressure sensor 34b is disposed on the discharge side of the compressor 21 and detects the pressure of the refrigerant discharged from the compressor 21.

  In the example of this embodiment, the condensation temperature of the heat source side heat exchanger 23 is obtained by converting the pressure of the discharge pressure sensor 34b into the saturation temperature, but the condensation temperature of the heat source side heat exchanger 23 is obtained. Can also be obtained by arranging a temperature sensor in the heat source side heat exchanger 23.

  FIG. 2 is a diagram schematically illustrating an example of the configuration of the refrigeration apparatus according to Embodiment 1 of the present invention. The control unit 3 controls the entire refrigeration apparatus 1, and the control unit 3 in the example of this embodiment is included in the heat source side control unit 31. The control unit 3 corresponds to the “refrigerant amount determination unit” of the present invention. The control unit 3 includes an acquisition unit 3a, a calculation unit 3b, a storage unit 3c, and a drive unit 3d. The acquisition unit 3a, the calculation unit 3b, and the drive unit 3d are configured to include, for example, a microcomputer, and the storage unit 3c is configured to include, for example, a semiconductor memory. The acquisition unit 3a acquires information such as temperature and pressure detected by sensors such as a pressure sensor and a temperature sensor. The calculation unit 3b performs processing such as calculation, comparison, and determination using the information acquired by the acquisition unit 3a. The drive unit 3d performs drive control of the compressor 21, valves, fans, and the like using the results calculated by the calculation unit 3b. The storage unit 3c stores physical property values (saturation pressure, saturation temperature, etc.) of the refrigerant, data for the calculation unit 3b to perform calculations, and the like. The calculation unit 3b can refer to or update the storage content of the storage unit 3c as necessary.

  The control unit 3 includes an input unit 3e and an output unit 3f. The input unit 3e inputs operation input from a remote controller or switches (not shown) or communication data from communication means (not shown) such as a telephone line or a LAN line. The output unit 3f outputs the processing result of the control unit 3 to a display unit (not shown) such as an LED or a monitor, and outputs it to a notification unit (not shown) such as a speaker, or a telephone line or a LAN line. To a communication means (not shown). In addition, when outputting information to a remote place by a communication means, it is good to provide the communication means (not shown) which has the same communication protocol in both the refrigeration apparatus 1 and a remote device (not shown).

  For example, it is possible to determine whether the refrigerant amount is insufficient or the like using the refrigeration apparatus 1 and a remote apparatus (not shown). In that case, for example, the calculation unit 3b calculates the temperature efficiency T of the first subcooler 22 using the information acquired by the acquisition unit 3a, and the output unit 3f calculates the temperature efficiency calculated by the calculation unit 3b. T is sent to the remote device. The remote device is provided with a refrigerant shortage determining means (not shown) for determining the shortage of the refrigerant amount, and determines the shortage of the refrigerant amount using the temperature efficiency T. By managing the refrigerant shortage information and the like by the remote device, it is possible to detect an abnormality or the like of the refrigeration device 1 at a place where the remote device is installed at an early stage. The maintenance of the refrigeration apparatus 1 can be performed at an early stage.

  In the above description, the example in which the control unit 3 is included in the heat source side control unit 31 has been described. However, the control unit 3 may be included in the use side control unit 32 or the heat source The side control unit 31 and the use side control unit 32 may be configured separately.

[Operation of refrigeration equipment (when the amount of refrigerant is appropriate)]
FIG. 3 is an example of a ph diagram of the refrigeration apparatus illustrated in FIG. 1 when the refrigerant amount is appropriate. First, the operation of the refrigeration apparatus 1 when the refrigerant amount is appropriate will be described. From the point K to the point L in FIG. 3, the compressor 21 illustrated in FIG. 1 compresses the refrigerant. From the point L to the point M in FIG. 3, the high-temperature and high-pressure gas refrigerant compressed by the compressor 21 in FIG. 1 is heat-exchanged by the heat source side heat exchanger 23 functioning as a condenser to be condensed and liquefied. Note that the refrigerant that has been heat-exchanged by the heat source side heat exchanger 23 and condensed and liquefied flows into the receiver 25 and is temporarily stored in the receiver 25. The amount of the refrigerant stored in the receiver 25 varies depending on the operation load, the outside air temperature, the condensation temperature, and the like of the usage-side unit 4.

  From the point M to the point N in FIG. 3, the liquid refrigerant stored in the receiver 25 in FIG. 1 is supercooled by the first subcooler 22. The degree of supercooling at the outlet of the first supercooler 22 is calculated by subtracting the temperature of the supercooler high-pressure side outlet temperature sensor 33d from the condensation temperature.

  The liquid refrigerant supercooled by the first subcooler 22 in FIG. 1 from the point N to the point O in FIG. 3 passes through the liquid side closing valve 28 and the liquid refrigerant extension pipe 6 to the usage side unit 4. It is sent and decompressed by the use side expansion valve 41 to become a low-pressure gas-liquid two-phase refrigerant.

  The gas-liquid two-phase refrigerant decompressed by the use side expansion valve 41 in FIG. 1 from the point O to the point K in FIG. 3 is gasified in the use side heat exchanger 42 functioning as an evaporator. The degree of superheat of the refrigerant is calculated by subtracting the evaporation temperature of the refrigerant detected by the use side heat exchange inlet temperature sensor 33e from the temperature detected by the use side heat exchange outlet temperature sensor 33f. The gas refrigerant gasified by the use side heat exchanger 42 returns to the compressor 21 via the gas refrigerant extension pipe 7, the gas side closing valve 29, and the accumulator 24.

  Next, the injection circuit will be described. The first injection circuit 71 is for lowering the refrigerant temperature of the discharge part of the compressor 21. The inlet of the first injection circuit 71 is connected between the outlet of the first subcooler 22 and the liquid side shut-off valve 28, and a part of the high-pressure liquid refrigerant subcooled by the first subcooler 22 is Then, the pressure is reduced by the injection amount adjusting valve 72 to become a two-phase refrigerant having an intermediate pressure, and flows into the injection portion of the compressor 21.

  The second injection circuit 73 is for lowering the refrigerating machine oil inside the compressor 21, the temperature of the motor, and the refrigerant temperature of the discharge unit. The inlet of the second injection circuit 73 is connected between the outlet of the first subcooler 22 and the liquid side shut-off valve 28, and a part of the high-pressure liquid refrigerant subcooled by the first subcooler 22 is Then, the pressure is reduced in the capillary tube 74 to become a low-pressure two-phase refrigerant and flows into the suction portion of the compressor 21.

[Operation of refrigeration equipment (when refrigerant amount is insufficient)]
FIG. 4 is an example of a ph diagram of the refrigeration apparatus illustrated in FIG. 1 when the amount of refrigerant is insufficient. For example, when the refrigerant leaks from the refrigeration apparatus 1 illustrated in FIG. 1 and the amount of the refrigerant decreases, the excess liquid refrigerant stored in the receiver 25 decreases while the excess liquid refrigerant is stored in the receiver 25. To do. While the surplus liquid refrigerant is present in the receiver 25, the refrigeration apparatus 1 operates in the same manner as when the refrigerant amount is appropriate, as shown in FIG.

  When the refrigerant further decreases and the excess liquid refrigerant in the receiver 25 disappears, the enthalpy at the outlet of the heat source side heat exchanger 23 functioning as a condenser increases as shown by a point M1 in FIG. The refrigerant state at the outlet of the heat exchanger 23 becomes a two-phase state. Further, as the enthalpy at the outlet of the heat source side heat exchanger 23 increases, the first subcooler 22 performs the condensing and supercooling of the two-phase refrigerant, so that the point N1 indicates The enthalpy at the outlet of the first subcooler 22 is also increased.

[Comparative Example 1]
In Comparative Example 1, the refrigerant amount is determined using the degree of supercooling of the refrigerant. For example, when the refrigerant amount is insufficient due to leakage of the refrigerant, the degree of supercooling is reduced as shown in FIG. Therefore, in Comparative Example 1, when the degree of supercooling becomes smaller than a preset threshold value, it is determined that the refrigerant amount is insufficient.

  FIG. 5 is a diagram illustrating the relationship among the refrigerant amount of the refrigeration apparatus illustrated in FIG. 1, the degree of supercooling of the first supercooler, and the operating conditions of the refrigeration apparatus. As shown in FIG. 5, the degree of supercooling of the first subcooler 22 varies greatly depending on the operating conditions of the refrigeration apparatus 1 (outside air temperature, heat exchange amount, refrigerant circulation amount, etc.). Therefore, as in Comparative Example 1, when using the degree of supercooling to determine whether the amount of refrigerant is insufficient, it is necessary to set the degree of supercooling threshold S low so as not to make an erroneous determination. In Modification 1, since the supercooling degree threshold value S must be set low, it takes a long time to determine whether the refrigerant amount is insufficient. For example, when the refrigerant is leaking, the amount of refrigerant leakage is large. turn into.

[Judgment of refrigerant amount]
Therefore, in this embodiment, the refrigerant amount is determined by using the temperature efficiency T of the first subcooler 22 that has a smaller variation with respect to changes in the operating conditions of the refrigeration apparatus 1 than the degree of supercooling. This will be described below.

  FIG. 6 is an example of the temperature change of the refrigerant when the refrigerant flows in the order of the heat source side heat exchanger, the receiver, and the air supercooler when the refrigerant amount is an appropriate amount in the refrigeration apparatus illustrated in FIG. FIG. In FIG. 6, the vertical axis indicates the temperature, and the temperature is higher at the top. The horizontal axis indicates the refrigerant path of the heat source side heat exchanger 23, the receiver 25, and the first subcooler 22. s1 is the refrigerant condensation temperature, s2 is the refrigerant temperature at the outlet of the first subcooler 22, and s3 is the outside air temperature.

The temperature efficiency T of the first subcooler 22 indicates the efficiency of the first subcooler 22, and the maximum temperature difference A is taken as the denominator and the actual temperature difference B is taken as the numerator. . In the first subcooler 22, the maximum possible temperature difference A is the difference between the condensation temperature s1 and the outside air temperature s3, and the actually possible temperature difference B is the condensation temperature s1 and the outlet of the first subcooler 22. Is the difference from the temperature s2. The temperature efficiency T is expressed by the following (Formula 1).
Temperature efficiency T = Actual temperature difference B / Maximum temperature difference A (Expression 1)

  FIG. 7 is a diagram for explaining the relationship among the refrigerant amount of the refrigeration apparatus shown in FIG. 1, the temperature efficiency of the first subcooler, and the operating conditions of the refrigeration apparatus. In FIG. 7, the horizontal axis represents the refrigerant amount of the refrigerant, and the vertical axis represents the temperature efficiency T of the first subcooler 22. As shown in FIG. 7, when the refrigerant amount decreases, the refrigerant amount becomes E, and the excess liquid refrigerant in the receiver 25 disappears, the temperature efficiency T of the first subcooler 22 decreases. Therefore, when the temperature efficiency T becomes smaller than the preset temperature efficiency threshold T1, it is determined that the refrigerant has leaked. The temperature efficiency T indicates the performance of the supercooling heat exchanger 5, and since the fluctuation due to the operating conditions of the refrigeration apparatus 1 is smaller than the degree of supercooling, a threshold is set for each operating condition of the refrigeration apparatus 1. Therefore, it is possible to improve the determination accuracy of the refrigerant amount shortage.

[Exception condition for refrigerant quantity judgment]
Even when the refrigerant amount is an appropriate amount, depending on the operating state of the refrigeration apparatus 1 illustrated in FIG. 1, the refrigerant amount determination using the temperature efficiency T of the first subcooler 22 becomes an erroneous determination. Therefore, it may be determined that the refrigerant amount is insufficient. If it is determined that the refrigerant amount is insufficient when the refrigerant amount is an appropriate amount, confusion will be caused. Note that the refrigerant amount is an appropriate amount, but when the refrigerant amount is determined to be insufficient, the refrigerant amount determination result may be the appropriate amount determination by replenishing the refrigerant. However, in that case, an unnecessary amount of refrigerant is sealed in the refrigeration apparatus 1, which increases the cost of the refrigeration apparatus 1. Further, if the amount of the refrigerant increases unnecessarily, if the refrigerant leaks, the amount of leakage until the refrigerant shortage can be determined by the refrigerant amount determination using the temperature efficiency T is increased. Moreover, when the amount of refrigerant increases unnecessarily, the amount of liquid back increases when liquid back occurs, which may lead to a malfunction of the compressor 21. Therefore, in the example of this embodiment, an exception condition for refrigerant amount determination is provided, and when the refrigerant amount determination corresponds to an exception condition that may be erroneously determined, the temperature efficiency T of the first subcooler 22 is set. The amount of refrigerant used is not determined. This will be described below.

[Exception condition 1 (during use-side fan delay control)]
Exception condition 1 is a case where user-side fan delay control is performed. The use-side fan delay control is performed to prevent warm air generated during the defrosting operation from being blown out into the cooling space. The time until the temperature of the use side heat exchanger 42 decreases after the defrosting operation is completed is, for example, several minutes, and the use side fan 43 operates before the temperature of the use side heat exchanger 42 decreases. Then, since warm air is blown out into the cooling space, the operation of the use side fan 43 is stopped until the temperature of the use side heat exchanger 42 decreases. And after the temperature of the use side heat exchanger 42 falls, the operation | movement of the use side fan 43 is restarted.

  When the operation of the usage-side fan 43 is stopped, heat exchange in the usage-side heat exchanger 42 is suppressed, so that the refrigerant that has passed through the usage-side heat exchanger 42 is in a gas-liquid two-phase state. There is. That is, the refrigerant flowing from the use side heat exchanger 42 to the compressor 21 in the gas state normally flows in the two-phase state when the use side fan delay control is performed, and the liquid refrigerant is stored in the accumulator 24. Therefore, when the use-side fan delay control is performed, the amount of refrigerant on the low-pressure side temporarily increases, and the amount of refrigerant on the high-pressure side temporarily decreases. As a result, when the use-side fan delay control is performed, the refrigerant amount determination using the temperature efficiency T may be erroneously determined. Therefore, at the time of use-side fan delay control, the refrigerant amount determination using the temperature efficiency T is not performed. When the use-side fan delay control is completed and the use-side fan 43 is operated, the refrigerant flowing from the use-side heat exchanger 42 to the compressor 21 is in a gas state, and the shortage of refrigerant on the high-pressure side is resolved.

  For example, the control unit 3 determines that the refrigeration apparatus 1 is performing the use-side fan delay control by acquiring the operating state of the refrigeration apparatus 1. Then, the control unit 3 determines that the refrigerant flowing from the use side heat exchanger 42 to the compressor 21 is in the gas state during the use side fan delay control or during the use side fan delay control and after the use side fan delay control. The refrigerant shortage determination is not performed for a certain period of time. Even when the use-side fan delay control is not performed, when the operation of the use-side fan 43 is stopped, the refrigerant amount determination using the temperature efficiency T may be erroneously determined as described above. There is. Therefore, when the operation of the use-side fan 43 is stopped, the refrigerant amount determination using the temperature efficiency T may not be performed.

  In addition, when the temperature efficiency T exceeds the preset set time and falls below the temperature efficiency threshold value T1, it can be determined that the refrigerant is insufficient. That is, the maximum time of the use side fan delay control is, for example, about 10 minutes, and the maximum time until the refrigerant flowing from the use side heat exchanger 42 to the compressor 21 becomes a gas state after the use side fan delay control is performed. Is, for example, about 10 minutes. Therefore, for example, the temperature efficiency T is “maximum time until the refrigerant flowing from the use-side heat exchanger 42 to the compressor 21 becomes a gas state after performing the“ maximum time of use-side fan delay control + use-side fan delay control ”. It is also possible to determine that the refrigerant is insufficient when it exceeds a set time (for example, 20 minutes) determined by “time” and falls below the temperature efficiency threshold T1.

[Exception condition 2 (when pulling down, evaporation temperature is high)]
Exception condition 2 is when the evaporation temperature is high during pull-down. Usually, when the internal temperature at the time of cooling after the refrigeration apparatus 1 is stopped for a long time is high, the operation may be performed in a state where the pressure on the low pressure side of the refrigerant circuit 10 is higher than usual although it is a short time. In this case, the pressure from the use side expansion valve 41 to the suction portion of the compressor 21 increases, and the refrigerant density increases. Since the required amount of refrigerant is expressed by density × volume, the required amount of refrigerant on the low pressure side temporarily increases, and the high pressure side such as the receiver 25, the first subcooler 22, the heat source side heat exchanger 23, etc. A refrigerant shortage state occurs. Therefore, at the time of pull-down, when the evaporation temperature is high, the refrigerant amount determination using the temperature efficiency T is not performed.

  FIG. 8 is a diagram for explaining that, in the refrigerant amount determination of this embodiment, when the compressor is an inverter compressor, the refrigerant amount determination is not performed according to the magnitude of the low pressure. FIG. 9 is a diagram for explaining that, in the refrigerant amount determination according to this embodiment, when the compressor is a constant speed compressor, the refrigerant amount determination is not performed according to the magnitude of the low pressure. . As shown in FIG. 8, when the compressor 21 is an inverter compressor, the operating frequency of the compressor 21 is increased so that the actual low pressure approaches the target low pressure P1 set in advance. It has been reduced. Further, as shown in FIG. 9, when the compressor 21 is a constant speed compressor, a low pressure cut ON value P4 is set to operate the compressor 21 when the low pressure increases, and when the low pressure decreases. A low pressure cut OFF value P3 for stopping the compressor 21 is set, and the compressor 21 is operated. That is, when the compressor 21 is an inverter compressor, the low pressure pressure during the operation of the compressor 21 is operated at a substantially target low pressure, and when the compressor 21 is a constant speed compressor, the compression is performed. Most of operations are less than the low pressure cut ON value for operating the machine 21. Therefore, if the current low pressure is higher than the target low pressure or the value obtained by adding a margin to the low pressure cut ON value as described below, the refrigerant shortage determination is not performed. That is, as shown in FIG. 8, when the compressor 21 is an inverter compressor, the refrigerant shortage determination is not performed when the current low pressure is larger than the target low pressure P1 + the pressure P2 of the margin α. As shown in FIG. 9, when the compressor 21 is a constant speed compressor, the refrigerant shortage determination is performed when the current low pressure is higher than the low pressure cut ON value P4 + the pressure P5 of the margin β. Absent.

[Exception condition 3 (when the solenoid valve for suction injection is open)]
Exception condition 3 is a case where the electromagnetic valve 75 for suction injection shown in FIG. 1 is open. When the electromagnetic valve 75 for suction injection is opened, a part of the high-pressure liquid refrigerant is decompressed by the capillary tube 74 and flows into the suction portion of the compressor 21. At this time, normally, the gas-liquid two-phase state from the low pressure suction electromagnetic valve 75 on the low pressure side, which is in the gas state, to the suction portion of the compressor 21, and the amount of refrigerant temporarily increases to the low pressure side. The high pressure side such as the first subcooler 22 and the heat source side heat exchanger 23 is in a refrigerant shortage state. Note that the case where the electromagnetic valve 75 for suction injection is opened is a rare situation, for example, when the intake gas temperature of the compressor 21 abnormally rises during pull-down after a long-term stop.

  Therefore, when the compressor 21 is in operation and the electromagnetic valve 75 for suction injection is open, and for a certain period of time after the electromagnetic valve 75 for suction injection is opened to closed, the electromagnetic valve 75 for suction injection is used. The gas-liquid two-phase state up to the suction portion of the compressor 21 is temporarily increased, the amount of refrigerant temporarily increases to the low pressure side, and the high pressure side such as the receiver 25, the first subcooler 22 and the heat source side heat exchanger 23 is in a refrigerant shortage state. Therefore, the refrigerant shortage determination is not performed. In the above description, the example in which the refrigerant shortage determination is not performed when performing the injection in the second injection circuit 73 has been described. However, when the injection in the first injection circuit 71 is performed, the refrigerant shortage is not performed. You may be comprised so that determination may not be performed. In that case, it is only necessary to determine whether or not to determine whether the refrigerant is insufficient by using the opening degree of the injection amount adjusting valve 72 or the like.

[Exception condition 4 (when the air volume of the heat source fan is low)]
In the above exception conditions 1 to 3, the example in which the refrigerant amount determination is not performed when the refrigerant on the high pressure side is temporarily insufficient is described. Exception condition 4 is a case where the air volume of the heat source side fan 27 is reduced. When the air volume of the heat source side fan 27 is reduced, for example, when the outside air is reduced, if the high pressure is too low, the differential pressure of the use side expansion valve 41 becomes small and the flow rate of the refrigerant cannot be secured. This is a case where the air volume of the heat source side fan 27 is reduced in order to keep it high. For example, in order to reduce the noise of the heat source side fan 27, the air volume of the heat source side fan 27 may be reduced.

  As for the temperature efficiency T, when the air volume of the heat source side fan 27 decreases, the condensation temperature increases, so that the maximum temperature difference A that is the difference between the condensation temperature and the outside air temperature increases. At this time, the actual possible temperature difference B, which is the difference between the condensation temperature and the outlet temperature of the first subcooler 22, is the maximum possible temperature difference A because the air volume of the heat source side fan 27 is reduced. Does not become large compared to. Therefore, when the air volume of the heat source side fan 27 is decreased, the temperature efficiency T is decreased. In particular, when the ambient temperature is low, such as -15 ° C, it is necessary to turn on / off the heat source side fan 27, and the maximum temperature difference A that is normally about 7K to 15K is 30K to 50K. The temperature efficiency T decreases. Therefore, when the air volume of the heat source side fan 27 is decreased, the difference between the outside air temperature and the condensation temperature is increased, or when the outside air temperature is lower than a certain temperature, the refrigerant shortage determination is not performed.

  FIG. 10 is a diagram illustrating an example of the relationship between the air volume of the heat source side fan and the temperature efficiency threshold. As shown in FIG. 10, by setting the temperature efficiency threshold T2 when the air volume of the heat source side fan 27 is reduced to a small value, compared to the temperature efficiency threshold T3 when the air volume of the heat source side fan 27 is large. In addition, the risk of erroneous determination of refrigerant amount determination using temperature efficiency T can be suppressed.

[Exception condition 5 (compressor stopped, fixed time after compressor startup)]
Exception condition 5 is a fixed time after the compressor is started while the compressor is stopped. FIG. 11 is a diagram illustrating the relationship between the condensation temperature, the outside air temperature, the outlet temperature of the first subcooler, and the temperature efficiency before and after the start of the compressor. For example, consider a case where the compressor 21 is started after the compressor 21 has been stopped for a long time. While the compressor 21 is stopped for a long time, the outside air temperature, the outlet temperature of the first subcooler 22 and the condensation temperature are substantially equal. In this case, if all the temperatures are equal, the temperature efficiency T = B / A = 0/0. However, in practice, due to sensor variations, for example, the condensation temperature is 25.0 ° C., the outside air temperature is 24.9 ° C., the outlet temperature of the first subcooler 22 is 24.8 ° C., and the temperature efficiency T = B /A=0.2/0.1=2.0. Note that the above example is merely an example, and in practice, the temperature efficiency T varies greatly due to sensor variations or the like during a long-term stop of the compressor 21. When the compressor 21 is started at the time m1, the temperature efficiency T is stabilized at a value between 0.0 and 1.0 at the time m2. The time from time m1 to time m2 is, for example, about 30 seconds to 1 minute.

  As described above, the temperature efficiency T is unstable for a certain time after the compressor 21 is started after the compressor 21 is stopped. For example, the compressor 21 is repeatedly stopped and operated in a short time. In such a case, the situation where the temperature efficiency T is low continues. As a result, even if the refrigerant is not leaking, the refrigerant determination using the temperature efficiency T may be insufficient. Therefore, the refrigerant shortage is not determined for a certain period of time after the compressor 21 is started after the compressor 21 is stopped.

[Refrigerant amount judgment operation]
FIG. 12 is a diagram illustrating an example of the refrigerant amount determination operation of the refrigeration apparatus illustrated in FIG. The refrigeration apparatus 1 according to this embodiment uses the temperature efficiency T of the first subcooler 22 to determine the refrigerant amount. Note that the determination of the refrigerant amount described below can also be applied to a refrigerant charging operation when the refrigeration apparatus 1 is installed or a refrigerant charging operation when the refrigeration apparatus 1 is maintained. The refrigerant amount determination operation may be executed when an instruction from a remote device (not shown) is received.

  In step ST1 of FIG. 12, the refrigeration apparatus 1 shown in FIG. In the normal operation control of the refrigeration apparatus 1, for example, the heat source side control unit 31 acquires operation data such as the pressure and temperature of the refrigerant circuit 10 detected by the sensors, and uses the operation data to condense the condensation temperature, the evaporation temperature, and the like. The control values such as target value and deviation are calculated to control the actuators. Hereinafter, the operation of the actuators will be described.

  For example, the heat source side control unit 31 controls the operating frequency of the compressor 21 so that the evaporation temperature of the refrigeration cycle of the refrigeration apparatus 1 matches the target temperature (for example, 0 ° C.). The evaporation temperature of the refrigeration cycle can also be obtained by converting the pressure detected by the suction pressure sensor 34a into a saturation temperature. For example, the heat source side control unit 31 increases the operation frequency of the compressor 21 when the current evaporation temperature is higher than the target temperature, and operates the compressor 21 when the current evaporation temperature is lower than the target value. Reduce the frequency.

  Further, for example, the heat source side control unit 31 blows air to the heat source side heat exchanger 23 so that the condensation temperature of the refrigeration cycle of the refrigeration apparatus 1 matches a target temperature (for example, 45 ° C.). Control the number of revolutions. The condensation temperature of the refrigeration cycle of the refrigeration apparatus 1 can also be obtained by converting the pressure detected by the discharge pressure sensor 34b into a saturation temperature. For example, the heat source side control unit 31 increases the number of rotations of the heat source side fan 27 when the current condensing temperature is higher than the target temperature, and increases the rotational speed of the heat source side fan 27 when the current condensing temperature is lower than the target temperature. Reduce the rotation speed.

  Further, for example, the heat source side control unit 31 adjusts the opening degree of the injection amount adjustment valve 72 of the first injection circuit 71 using the signals obtained from the sensors, or for the suction injection of the second injection circuit 73. The opening degree of the electromagnetic valve 75 is adjusted. For example, when the current discharge temperature of the compressor 21 is high, the heat source side control unit 31 opens the injection amount adjusting valve 72 or the suction injection electromagnetic valve 75 and the current discharge temperature of the compressor 21 is low. Closes the injection amount adjusting valve 72 or the electromagnetic valve 75 for suction injection. Further, for example, the heat source side control unit 31 controls the rotation speed of the use side fan 43 that blows air to the use side unit 4.

  In step ST2, the heat source side control unit 31, for example, the outlet temperature of the heat source side heat exchanger 23, the temperature of the outlet of the first subcooler 22, the outside air temperature detected by the suction outside air temperature sensor 33c and the discharge pressure sensor 34b. Is used to calculate the temperature efficiency T of the first subcooler 22.

  In step ST3, the heat source side control unit 31 acquires the operating state of the refrigeration apparatus 1. When the operating state of the refrigeration apparatus 1 corresponds to the “exception condition for refrigerant amount determination”, the process returns to step ST1, and the operating state of the refrigeration apparatus 1 corresponds to the “exception condition for refrigerant amount determination”. If not, the process proceeds to step ST4.

  In step ST4, the heat source side control unit 31 determines whether the operation control of the refrigeration apparatus 1 performed in step ST1 is stable. If the operation control of the refrigeration apparatus 1 is not stable, the process returns to step ST1, and if the operation control of the refrigeration apparatus 1 is stable, the process proceeds to step ST5.

  In step ST5, the heat source side control unit 31 determines whether or not the refrigerant amount is appropriate by comparing the refrigerant amount determination parameter with its reference value. Specifically, a deviation amount ΔT (= T−Tm) between the temperature efficiency T of the first subcooler 22 and the determination threshold value Tm is obtained, and it is determined whether or not the deviation amount ΔT is a positive value. If the deviation amount ΔT is positive, the heat source side control unit 31 determines that the refrigerant amount is not insufficient, and proceeds to step ST6. If the deviation amount ΔT is negative, the heat source side control unit 31 determines that the refrigerant amount is insufficient, and proceeds to step ST7. At this time, the temperature efficiency T of the first subcooler 22 is preferably a moving average of a plurality of temperature efficiencies T that are temporally different from each other, rather than using an instantaneous value. By taking a moving average of a plurality of temperature efficiencies T that are temporally different, the stability of the refrigeration cycle can be taken into consideration. The determination threshold value Tm may be stored in advance in the storage unit 3c of the heat source side control unit 31, for example, or may be set by an input from a remote controller or a switch, or an instruction from a remote device (not shown). May be set.

  When the refrigerant amount determination result in step ST5 indicates that the refrigerant amount is appropriate, the heat source side control unit 31 outputs in step ST6 that the refrigerant amount is appropriate. When the amount of refrigerant is appropriate, the fact that the amount of refrigerant is appropriate is displayed, for example, on a display unit (not shown) such as an LED or a liquid crystal disposed in the refrigeration apparatus 1, or the amount of refrigerant is appropriate. Is transmitted to a remote device (not shown).

  When the refrigerant amount determination result in step ST5 is that the refrigerant amount is insufficient, the heat source side control unit 31 outputs in step ST7 that the refrigerant amount is abnormal. When the refrigerant amount is abnormal, for example, an alarm indicating that the refrigerant amount is abnormal is displayed on a display unit (not shown) such as an LED or a liquid crystal provided in the refrigeration apparatus 1, or the refrigerant amount Is transmitted to a remote device (not shown). In addition, since an emergency may be required when the amount of refrigerant is abnormal, it may be configured to notify the service person of the occurrence of abnormality directly through a telephone line or the like.

  In the above embodiment, the temperature efficiency T is calculated in step ST2, and it is determined whether or not the refrigerant amount is determined in steps ST3 and ST4. However, step ST3 and step ST4 are used. After step ST2, step ST2 may be executed. By performing the calculation of the temperature efficiency T after determining whether or not to determine the refrigerant amount, the amount of processing that the heat source side control unit 31 performs the calculation can be reduced.

  As described above, in this embodiment, the temperature efficiency T is used to determine the amount of refrigerant flowing in the refrigerant circuit 10 of the refrigeration apparatus 1, so that even if the refrigerant leaks, The refrigerant leakage can be detected at an early stage.

  Furthermore, in this embodiment, when the operation state of the refrigeration apparatus 1 is acquired and the operation state of the refrigeration apparatus 1 corresponds to the “exception condition for refrigerant amount determination”, the refrigerant amount using the temperature efficiency T Since the determination is not performed, the risk of erroneous determination of the refrigerant amount is suppressed. As a result, in this embodiment, since the amount of refrigerant can be set to an appropriate amount, the cost of the refrigerant can be reduced. Furthermore, in this embodiment, since the amount of refrigerant is an appropriate amount, even if the refrigerant leaks, the amount of refrigerant released into the atmosphere can be reduced. Furthermore, in this embodiment, since the amount of refrigerant is an appropriate amount, even if the operation of the expansion valve or the like becomes abnormal and liquid back occurs, the amount of liquid back to the compressor 21 is reduced. Can be reduced. Therefore, the refrigeration apparatus 1 of this embodiment has improved reliability.

  In the operation control described above, control for specifying the condensation temperature and the evaporation temperature is not performed. However, for example, the control may be performed so that the condensation temperature and the evaporation temperature are constant. Further, for example, it is not necessary to control the condensing temperature and the evaporating temperature by setting the operating frequency of the compressor 21 and the rotation speed of the heat source side fan 27 of the heat source side unit 2 as constant values. Further, for example, the control may be performed so that one of the condensation temperature and the evaporation temperature becomes a target value. By controlling the operating state of the refrigeration apparatus 1 to a certain condition, the degree of subcooling of the first subcooler 22 and the fluctuation of the operating state variable that varies according to the degree of subcooling are reduced, and the threshold value can be easily determined. This makes it easier to determine whether the refrigerant amount is insufficient.

  In addition, the refrigerant amount determination operation of this embodiment is applied to the refrigerant charging operation at the initial stage of installation of the refrigeration apparatus 1 or the refrigerant charging operation when the refrigerant is once discharged and refilled at the time of maintenance. It is possible to reduce the time required for the operator and reduce the load on the worker.

[Modification 1]
FIG. 13 shows a first modification of FIG. Compared with the refrigeration apparatus 1 described in FIG. 1, the heat source side unit 2 </ b> A of the refrigeration apparatus 1 </ b> A according to the first modification has a second subcooler 26 downstream of the first subcooler 22, as shown in FIG. 13. It has further. The second subcooler 26 corresponds to the “supercooler” of the present invention. The second subcooler 26 includes, for example, a double pipe or a plate-type heat exchanger, and has a high pressure refrigerant flowing in the heat source side refrigerant circuit 10b and an intermediate pressure flowing in the first injection circuit 71A. Heat exchange with the refrigerant is performed. A part of the refrigerant that has passed through the second subcooler 26 is expanded by the injection amount adjustment valve 72 to become an intermediate-pressure refrigerant, and exchanges heat with the refrigerant that has passed through the second subcooler 26. As a result, in the second modification, the high-pressure refrigerant flowing from the receiver 25 and heat-exchanged by the second subcooler 26 is further subcooled. Further, the intermediate-pressure refrigerant that flows in from the injection amount adjustment valve 72 and exchanges heat with the second subcooler 26 becomes a refrigerant having a high dryness, so that the discharge temperature of the compressor 21 is lowered in order to lower the discharge temperature of the compressor 21. Injection into the suction side. The refrigerant determination operation in the first modification is performed using the temperature efficiency of the first subcooler 22, the temperature efficiency of the second subcooler 26, or the temperature efficiency of the first subcooler 22 and the second subcooler 26. It's fine. In the first modification, the first subcooler 22 may be omitted, and the refrigerant that has flowed out from the receiver 25 may flow into the second subcooler 26.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. That is, the configuration of the above embodiment may be improved as appropriate, or at least a part of the configuration may be replaced with another configuration. Furthermore, the constituent elements that are not particularly limited with respect to the arrangement are not limited to the arrangement disclosed in the embodiment, and can be arranged at positions where the functions can be achieved.

  DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus, 1A refrigeration apparatus, 2 heat source side unit, 2A heat source side unit, 3 control part, 3a acquisition part, 3b calculating part, 3c memory | storage part, 3d drive part, 3e input part, 3f output part, 4 utilization side unit 5, supercooling heat exchanger, 6 liquid refrigerant extension pipe, 7 gas refrigerant extension pipe, 10 refrigerant circuit, 10a utilization side refrigerant circuit, 10b heat source side refrigerant circuit, 21 compressor, 22 first supercooler, 23 heat source side Heat exchanger, 24 accumulator, 25 receiver, 26 second supercooler, 27 heat source side fan, 28 liquid side shutoff valve, 29 gas side shutoff valve, 31 heat source side control unit, 32 use side control unit, 33a suction temperature sensor 33b Discharge temperature sensor, 33c Suction outside air temperature sensor, 33d Supercooler high pressure side outlet temperature sensor, 33e Usage side heat exchange inlet temperature sensor, 33f Usage side Heat exchange outlet temperature sensor, 33g Suction air temperature sensor, 34a Suction pressure sensor, 34b Discharge pressure sensor, 41 User side expansion valve, 42 User side heat exchanger, 43 User side fan, 71 First injection circuit, 71A First injection Circuit, 72 injection amount adjustment valve, 73 second injection circuit, 74 capillary tube, 75 solenoid valve for suction injection, T temperature efficiency, T1 temperature efficiency threshold, T2 temperature efficiency threshold, T3 temperature efficiency threshold.

A refrigeration apparatus according to the present invention includes a heat source side unit having a heat source side heat exchanger and a supercooler functioning as a compressor and a condenser, and a usage side heat exchanger functioning as a usage side expansion valve and an evaporator. A refrigerating apparatus having a refrigerant circuit that is connected by piping and circulates a refrigerant, the degree of supercooling of the refrigerant at the outlet of the subcooler being a maximum temperature difference of the subcooler. A refrigerant amount determination unit that determines the amount of refrigerant charged in the refrigerant circuit using the temperature efficiency of the subcooler, which is a value obtained by division, includes a refrigerant amount determination unit for determining that the refrigerant amount is insufficient. A temperature efficiency threshold value is stored, and the temperature efficiency threshold value is changed according to the operating state of the refrigeration apparatus .

Claims (9)

A heat source side unit having a heat source side heat exchanger and a supercooler functioning as a compressor and a condenser, and at least one usage side unit having a usage side expansion valve and a usage side heat exchanger functioning as an evaporator; Is a refrigeration apparatus having a refrigerant circuit connected by piping and circulating the refrigerant,
Using the temperature efficiency of the subcooler, which is a value obtained by dividing the degree of supercooling of the refrigerant at the outlet of the subcooler by the maximum temperature difference of the subcooler, the amount of refrigerant charged in the refrigerant circuit is A refrigerant amount determination unit for determining,
The refrigerant amount determination unit acquires the operating state of the refrigeration apparatus and does not determine the refrigerant amount when there is a possibility that the determination of the refrigerant amount is erroneously determined.
Refrigeration equipment. If there is a possibility that the determination of the refrigerant amount is erroneously determined, the high-pressure side refrigerant from the heat source side heat exchanger to the inlet of the usage side expansion valve temporarily decreases, and from the outlet of the usage side expansion valve. When the low-pressure side refrigerant to the suction side of the compressor temporarily increases,
The refrigeration apparatus according to claim 1. A user-side fan that blows air to the user-side heat exchanger;
The high-pressure side refrigerant from the heat source side heat exchanger to the inlet of the usage side expansion valve temporarily decreases, and the low pressure side refrigerant from the outlet of the usage side expansion valve to the suction side of the compressor temporarily increases. If this is the case, the amount of air blown by the use-side fan is temporarily reduced.
The refrigeration apparatus according to claim 2. The high-pressure side refrigerant from the heat source side heat exchanger to the inlet of the usage side expansion valve temporarily decreases, and the low pressure side refrigerant from the outlet of the usage side expansion valve to the suction side of the compressor temporarily increases. If this is the case, pull down the refrigeration device,
The refrigeration apparatus according to claim 2. An injection circuit for injecting a part of the refrigerant cooled by the heat source side heat exchanger into the compressor;
Further comprising an on-off valve disposed in the injection circuit,
The high-pressure side refrigerant from the heat source side heat exchanger to the inlet of the usage side expansion valve temporarily decreases, and the low pressure side refrigerant from the outlet of the usage side expansion valve to the suction side of the compressor temporarily increases. Is, it is a case of opening the on-off valve,
The refrigeration apparatus according to claim 2. A heat source side fan for blowing air to the heat source side heat exchanger;
The case where the determination of the refrigerant amount is likely to be an erroneous determination is a case where the amount of air blown by the heat source side fan is temporarily reduced.
The refrigeration apparatus according to claim 1. When there is a possibility that the determination of the refrigerant amount may be an erroneous determination, it is a certain time after the compressor is stopped and after the compressor is started.
The refrigeration apparatus according to claim 1. The refrigerant amount determination unit stores a temperature efficiency threshold for determining that the amount of refrigerant is insufficient, and the temperature efficiency threshold is changed according to an operating state of the refrigeration apparatus.
The refrigeration apparatus according to claim 1. A heat source side fan for blowing air to the heat source side heat exchanger;
The temperature efficiency threshold is changed according to the amount of air blown by the heat source side fan,
The refrigeration apparatus according to claim 8.

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