JP6590945B2 - Refrigeration equipment - Google Patents

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, 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, and thus 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 to solve the above-described problems, and an object of the present invention is to provide a refrigeration apparatus that can accurately determine the amount of refrigerant.

The refrigeration apparatus according to the present invention includes a compressor, a condenser, a supercooler, a decompression device, and an evaporator, a refrigerant circuit that circulates the refrigerant, a refrigerant amount determination unit that determines the refrigerant amount of the refrigerant circuit, wherein the injection circuit for flowing into the intermediate-pressure section or inhalation of a part of the refrigerant passing through the subcooler said compressor, e Bei and a solenoid valve provided in the injection circuit, the subcooler, The refrigerant that has passed through the condenser is supercooled by heat exchange with a cooling fluid, and the temperature difference between the temperature of the refrigerant flowing into the supercooler and the temperature of the refrigerant flowing out of the subcooler is When the value obtained by dividing the temperature difference between the temperature of the refrigerant flowing into the subcooler and the temperature of the cooling fluid flowing into the subcooler is the temperature efficiency of the subcooler, the refrigerant amount determination unit is The operating state of the equipment is a preset amount of refrigerant When the predetermined exceptional condition is not met, the refrigerant amount determination using the temperature efficiency is performed, and when the temperature efficiency falls below a threshold, it is determined that the refrigerant amount is insufficient, and the refrigerant amount in the refrigerant circuit is determined. The threshold value is changed based on at least one of a condensation temperature and an evaporation temperature, and the exceptional condition includes a case where the electromagnetic valve is open .

  According to 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 a ph diagram when the refrigerant quantity is appropriate in the refrigeration apparatus according to Embodiment 1 of the present invention. It is an example of the ph diagram when the refrigerant | coolant amount runs short in the refrigeration apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the relationship between the refrigerant | coolant amount in the freezing apparatus of the comparative example 1 of Embodiment 1 of this invention, the supercooling degree of a 1st supercooler, and the operating conditions of a freezing apparatus. It is a figure explaining an example of the temperature change of a refrigerant | coolant when the refrigerant | coolant amount is an appropriate quantity in the refrigeration apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the relationship between the refrigerant | coolant amount in the freezing apparatus which concerns on Embodiment 1 of this invention, the temperature efficiency of a 1st subcooler, and the operating conditions of a freezing apparatus. In the refrigerant quantity determination of Embodiment 1 of this invention, when a compressor is an inverter compressor, it is a figure for demonstrating not performing refrigerant quantity determination according to the magnitude | size of a low pressure pressure. In the refrigerant quantity determination of Embodiment 1 of this invention, when a compressor is a constant speed compressor, it is a figure for demonstrating not performing refrigerant quantity determination according to the magnitude | size of a low pressure pressure. In refrigerant | coolant amount determination of Embodiment 1 of this invention, 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. In refrigerant | coolant amount determination of Embodiment 1 of this invention, 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 the starting of a compressor. It is a figure explaining an example of refrigerant | coolant amount determination operation | movement of the freezing apparatus which concerns on Embodiment 1 of this invention. It is a refrigerant circuit figure which shows the structure of the freezing apparatus which concerns on the modification 1 of Embodiment 1 of this invention. It is a refrigerant circuit figure which shows the structure of the freezing apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the relationship between the refrigerant | coolant amount and temperature efficiency in the freezing apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the relationship between the refrigerant | coolant amount in the refrigeration apparatus which concerns on Embodiment 2 of this invention, temperature efficiency, and the driving | running state of a refrigeration apparatus. It is a ph diagram in the driving | running states 1 and 2 shown in FIG. It is a figure which shows an example of the determination threshold value map memorize | stored in ROM of the heat-source side control part of the freezing apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows an example of the determination threshold value map memorize | stored in ROM of the heat-source side control part of the freezing apparatus which concerns on the modification 2 of Embodiment 2 of this invention.

  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]
FIG. 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 filled in the refrigerant circuit 10 of the present embodiment is, for example, R410A that is an HFC-based 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 usage-side refrigerant circuit 10 a includes a usage-side expansion valve 41 (an example of a decompression device) and a usage-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. Note that the decompression device may be disposed in the heat source side unit 2, and in that case, the decompression device is, for example, between the first subcooler 22 and the liquid side shut-off valve 28 of the heat source side unit 2. It is arranged. The use side heat exchanger 42 is, for example, a fin-and-tube heat exchanger configured to include a heat transfer tube and a plurality 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 multiblade 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 that constitutes a part of the refrigerant circuit 10, a first injection circuit 71, a second injection circuit 73, and a heat source side control unit 31. 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 uses either the first injection circuit 71 or the second injection circuit 73. The structure which has may be sufficient.

  The heat source side refrigerant circuit 10b 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 first injection circuit 71 includes an injection amount adjustment valve 72. The second injection circuit 73 divides 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 to flow into the suction portion of the compressor 21. . The second injection circuit 73 includes 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 plurality 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 a container that 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 has a function of storing excess liquid refrigerant and a function of gas-liquid separation of the refrigerant. The surplus liquid refrigerant is generated in the refrigerant circuit 10 in accordance with, for example, the load size of the usage-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 the present 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 heat source side fan 27 blows outside air sucked from the outside of the heat source side unit 2 to 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 shut-off valve 28 and the gas side shut-off valve 29 are composed of valves that open and close such as electromagnetic valves, ball valves, open / close valves, and operation valves, for example. 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 circuit 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 part and sensors with which the refrigerating apparatus 1 of this Embodiment is provided are demonstrated. 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 has a microcomputer including a CPU, a ROM, a RAM, an I / O port, a timer, and the like. 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 has a microcomputer including a CPU, ROM, RAM, I / O port, timer, and the like. The use side control unit 32 and the heat source side control unit 31 can exchange control signals by communication. For example, the use side control unit 32 receives instructions from the heat source side control unit 31 and controls the use side unit 4.

  The refrigeration apparatus 1 according to the present embodiment includes an intake temperature sensor 33a, a discharge temperature sensor 33b, a suction outside air temperature sensor 33c, a supercooler outlet temperature sensor 33d, a use side heat exchanger inlet temperature sensor 33e, and a use side heat exchanger. It includes an outlet temperature sensor 33f, an intake air temperature sensor 33g, an intake 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 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 connected to the heat source side control unit 31. It is connected. The use side heat exchanger inlet temperature sensor 33e, the use side heat exchanger outlet temperature sensor 33f, and the intake air temperature sensor 33g are disposed 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 outlet temperature sensor 33d detects the temperature of the refrigerant flowing out from the first subcooler 22. The use side heat exchanger inlet temperature sensor 33e detects the temperature of the gas-liquid two-phase refrigerant flowing into the use side heat exchanger 42, that is, the evaporation temperature of the refrigerant. The use side heat exchanger outlet temperature sensor 33f detects the temperature of the refrigerant that has flowed out of the use side heat exchanger. The sensor for detecting the temperature of the refrigerant is disposed, for example, in contact with the refrigerant pipe or inserted into the refrigerant pipe.

  The suction outside air temperature sensor 33 c detects the ambient temperature outside the room by detecting the temperature of the air before passing through the heat source side heat exchanger 23 or the first subcooler 22. 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 the present embodiment, the refrigerant condensing temperature in the heat source side heat exchanger 23 is obtained by converting the pressure of the discharge pressure sensor 34b into the saturation temperature. It 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 the present embodiment. The control unit 3 controls the entire refrigeration apparatus 1, and the control unit 3 in the example of the present 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 processing, and the like. The calculation unit 3b can refer to or update the storage contents 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 is used to input an operation input from a remote controller or switches (not shown), or communication data from a 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). When information is output to a remote place by communication means, communication means (not shown) having the same communication protocol for both the refrigeration apparatus 1 and a remote device (not shown) provided at the remote place. It is good to provide.

  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 when the refrigerant amount is appropriate in the refrigeration apparatus according to the present embodiment. 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 of the use side unit 4, the outside air temperature, the condensation temperature, and the like.

  The liquid refrigerant flowing out from the receiver 25 in FIG. 1 from the point M to the point N in FIG. 3 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 detected by the supercooler outlet temperature sensor 33d from the condensation temperature. That is, the degree of supercooling refers to the saturated liquid temperature on the high pressure side (for example, the temperature at point M) and the outlet temperature (for example, the point N at the point N) in the subcooler or condenser (in this example, the first subcooler 22). 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. Note that the degree of superheat of the refrigerant is calculated by subtracting the evaporation temperature of the refrigerant detected by the use side heat exchanger inlet temperature sensor 33e from the temperature detected by the use side heat exchanger 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 closing valve 28. A part of the high-pressure liquid refrigerant supercooled by the first subcooler 22 flows into the first injection circuit 71 and is reduced in pressure by the injection amount adjustment valve 72 to become a two-phase refrigerant having an intermediate pressure. Flows into the section.

  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 closing valve 28. Part of the high-pressure liquid refrigerant supercooled by the first subcooler 22 flows into the second injection circuit 73, is decompressed by the capillary tube 74, becomes a low-pressure two-phase refrigerant, and flows into the suction portion of the compressor 21. To do.

[Operation of refrigeration equipment (when refrigerant amount is insufficient)]
FIG. 4 is an example of a ph diagram when the refrigerant amount is insufficient in the refrigeration apparatus according to the present embodiment. 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]
Here, the comparative example 1 of this Embodiment is demonstrated. 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, the degree of supercooling of the first subcooler, and the operating conditions of the refrigeration apparatus in the refrigeration apparatus of Comparative Example 1 of the present embodiment. 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 the determination of the refrigerant amount shortage is performed using the degree of supercooling, it is necessary to set the supercooling degree threshold S low so as not to make an erroneous determination. In Comparative Example 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 the present embodiment, the refrigerant amount is determined using the temperature efficiency T of the first subcooler 22 that has a smaller variation with respect to the change in the operating condition of the refrigeration apparatus 1 than the degree of supercooling. This will be described below.

  FIG. 6 is a diagram for explaining an example of a temperature change of the refrigerant when the refrigerant amount is an appropriate amount in the refrigeration apparatus according to the present embodiment. The vertical axis in FIG. 6 represents temperature. The horizontal axis represents the path through which the refrigerant flows from right to left (in order 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. s1, s2, and s3 satisfy the relationship of s1> s2> s3.

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 temperature difference A that can be taken is the difference between the condensation temperature s1 and the outside air temperature s3 (A = s1-s3). The actual temperature difference B is the difference between the condensation temperature s1 and the temperature s2 at the outlet of the first subcooler 22 (B = s1−s2). The temperature efficiency T is represented by the following formula (1).
Temperature efficiency T = actual temperature difference B / maximum possible temperature difference A (1)

  FIG. 7 is a diagram for explaining the relationship among the refrigerant amount, the temperature efficiency of the first subcooler, and the operating conditions of the refrigeration apparatus in the refrigeration apparatus according to the present embodiment. In FIG. 7, the horizontal axis represents the amount of refrigerant charged in the refrigerant circuit, 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 subcooler (in this example, the first subcooler 22), and since the fluctuation due to the operating condition of the refrigeration apparatus 1 is smaller than the degree of supercooling, the temperature efficiency T of the refrigeration apparatus 1 It is possible to improve the determination accuracy of the refrigerant amount shortage without setting a threshold value for each operation condition.

[Exception condition for refrigerant quantity judgment]
Depending on the operating state of the refrigeration apparatus 1, the refrigerant amount determination using the temperature efficiency T of the first subcooler 22 may be erroneously determined. In this case, even if the actual refrigerant amount is an appropriate amount, it may be determined that the refrigerant amount is insufficient. If it is determined that the amount of refrigerant is insufficient when the actual amount of refrigerant is an appropriate amount, confusion will be caused. Note that the actual amount of refrigerant is an appropriate amount, but when it is determined that the amount of refrigerant is insufficient, replenishing the refrigerant may result in the determination of the amount of refrigerant being an appropriate amount. 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 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 will increase. 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 present embodiment, an exception condition for the 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 used. The refrigerant amount 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 from the end of the defrosting operation until the temperature of the use side heat exchanger 42 decreases is, for example, several minutes. If the use side fan 43 operates before the temperature of the use side heat exchanger 42 decreases, warm air is blown into the cooling space. For this reason, 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 use-side fan 43 is stopped, heat exchange in the use-side heat exchanger 42 is suppressed, and therefore the refrigerant that has passed through the use-side heat exchanger 42 is in a gas-liquid two-phase state. There is. That is, the refrigerant flowing in the gas state from the use side heat exchanger 42 to the compressor 21 at the normal time 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 the low-pressure side refrigerant temporarily increases, and the amount of the high-pressure side refrigerant 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. And the control part 3 is the time during implementation of use side fan delay control, or the time until the refrigerant | coolant which flows from the use side heat exchanger 42 to the compressor 21 will be in a gas state after completion | finish of use side fan delay control. The refrigerant shortage is not determined. 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 time for performing the use side fan delay control is, for example, about 10 minutes at the maximum, and the 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 completed. Is, for example, about 10 minutes at the maximum. For this reason, the control unit 3 can also determine that the refrigerant is insufficient when the temperature efficiency T exceeds a predetermined set time (for example, about 20 minutes) and falls below the temperature efficiency threshold T1. The set time is, for example, the maximum time (for example, 10 minutes) for performing the use side fan delay control, and the refrigerant flowing from the use side heat exchanger 42 to the compressor 21 after the use side fan delay control is in a gas state. It can be determined by the sum of the maximum time (for example, 10 minutes) until

[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 according to the present 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 the present embodiment, when the compressor is a constant speed compressor, the refrigerant amount determination is not performed according to the magnitude of the low pressure. . 8 and 9, the horizontal axis represents time, and the vertical axis represents 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 substantially the target low pressure P1. When the compressor 21 is a constant speed compressor, the low pressure during operation of the compressor 21 is equal to or lower than the low pressure cut ON value P4 in most periods. Therefore, if the current low pressure is higher than the target low pressure P1 or the value obtained by adding a margin to the low pressure cut ON value P4, the lack of refrigerant is not determined. That is, as shown in FIG. 8, when the compressor 21 is an inverter compressor, when the current low pressure is larger than the pressure P2 (P2 = P1 + α) obtained by adding the margin α to the target low pressure P1, Does not determine whether the refrigerant is insufficient. As shown in FIG. 9, when the compressor 21 is a constant speed compressor, the current low pressure is larger than the pressure P5 (P5 = P4 + β) obtained by adding the margin β to the low pressure cut ON value P4. In addition, the lack of refrigerant is not determined.

[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 electromagnetic valve 75 for suction injection is opened only in rare situations such as 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 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.

  When the air volume of the heat source side fan 27 is decreased, the condensation temperature is increased, so that the maximum temperature difference A that is the difference between the condensation temperature and the outside air temperature is increased. At this time, the actual temperature difference B, which is the difference between the condensation temperature and the outlet temperature of the first subcooler 22, is compared with the maximum possible temperature difference A because the air volume of the heat source side fan 27 is reduced. And does not grow. Therefore, when the air volume of the heat source side fan 27 is decreased, the temperature efficiency T is decreased. In particular, when the air temperature is low, such as about −15 ° C., the heat source side fan 27 needs to be intermittently operated, so the substantial air volume of the heat source side fan 27 decreases. Further, at the low outside air temperature, the maximum possible temperature difference A, which is usually about 7K to 15K, is expanded to 30K to 50K. Therefore, the temperature efficiency T further decreases at the low outside air temperature. 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 flow rate of the heat source side fan and the temperature efficiency threshold in the refrigerant amount determination according to the present embodiment. The horizontal axis in FIG. 10 represents the air volume of the heat source side fan 27 in the range of 0% to 100%, and the vertical axis represents the temperature efficiency T. As shown in FIG. 10, the temperature efficiency threshold is set based on the air volume of the heat source side fan 27. For example, the temperature efficiency threshold T2 when the air volume of the heat source side fan 27 is small is set to a value smaller than the temperature efficiency threshold T3 when the air volume of the heat source side fan 27 is large. Thereby, the possibility of erroneous determination of the refrigerant amount determination using the temperature efficiency T can also be suppressed.

[Exception condition 5 (compressor stopped, fixed time after compressor startup)]
Exception condition 5 is a fixed time after the compressor is stopped and after the compressor is started. FIG. 11 is a diagram for explaining the relationship among 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 in the refrigerant amount determination according to the present embodiment. The horizontal axis in FIG. 11 represents time. 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 during a certain period of time after the compressor 21 is stopped and after the compressor 21 is started. For example, when the stop and operation of the compressor 21 are repeated in a short time, the state where the temperature efficiency T is low is continued. As a result, even if the refrigerant is not leaking, it may be determined that the refrigerant is insufficient in the refrigerant amount determination using the temperature efficiency T. Therefore, the refrigerant shortage determination is not performed while the compressor 21 is stopped and for a certain period of time after the compressor 21 is started.

[Refrigerant amount judgment operation]
FIG. 12 is a diagram for explaining an example of the refrigerant amount determination operation of the refrigeration apparatus according to the present embodiment. The refrigeration apparatus 1 of the present embodiment uses the temperature efficiency T of the first subcooler 22 to determine the refrigerant amount. 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, normal operation control of the refrigeration apparatus 1 is performed. In the normal operation control of the refrigeration apparatus 1, 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, for example, the condensation temperature and the evaporation temperature. The control values such as the target value and deviation are calculated, and the actuators are controlled. 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.

  In addition, for example, the heat source side control unit 31 adjusts the opening of the injection amount adjusting valve 72 of the first injection circuit 71 using a signal obtained from the sensors, or for 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 adjustment 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) with respect to the determination threshold value Tm of the temperature efficiency T of the first subcooler 22 is obtained, and it is determined whether the deviation amount ΔT is a positive value or zero. If the deviation amount ΔT is a positive value or 0, 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 a negative value, 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. Note that 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 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 is an appropriate refrigerant amount, the heat source side control unit 31 outputs in step ST6 that the refrigerant amount is appropriate. If the refrigerant amount is appropriate, the fact that the refrigerant amount is appropriate is displayed on a display unit (not shown) such as an LED or a liquid crystal display device provided in the refrigeration apparatus 1, or the refrigerant amount Is sent 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 that the refrigerant amount is abnormal is displayed on a display unit (not shown) such as an LED or a liquid crystal display device provided in the refrigeration apparatus 1, or A signal indicating that the refrigerant amount is abnormal 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, steps ST3 and 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 the present 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 the present 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 the present embodiment, since the amount of refrigerant can be set to an appropriate amount, the cost of the refrigerant can be reduced. Furthermore, in the present embodiment, since the amount of refrigerant is an appropriate amount, even if the refrigerant leaks, the amount of refrigerant released to the atmosphere can be reduced. Furthermore, in this embodiment, since the refrigerant amount is an appropriate amount, even if the operation of the expansion valve or the like becomes abnormal and a liquid back occurs, the liquid back amount to the compressor 21 is reduced. Can be reduced. Therefore, the refrigeration apparatus 1 of the present 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, the condensing temperature and the evaporating temperature may not be controlled by setting the operation frequency of the compressor 21 and the rotation speed of the heat source side fan 27 of the heat source side unit 2 to be constant values, respectively. 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 subcooling degree of the first subcooler 22 and the fluctuation of the operating state quantity that varies according to the degree of subcooling are reduced, so the threshold value can be easily determined. Thus, it becomes easier to determine whether the refrigerant amount is insufficient.

  In addition, the refrigerant amount determining operation of the present 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 charged 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 is a refrigerant circuit diagram illustrating a configuration of a refrigeration apparatus according to Modification 1 of the present embodiment. As illustrated in FIG. 13, the heat source side unit 2A of the refrigeration apparatus 1A according to the first modification includes a second excess unit provided downstream of the first subcooler 22 as compared with the refrigeration apparatus 1 illustrated in FIG. A cooler 26 is further included. The second subcooler 26 corresponds to the “supercooler” of the present invention. The second subcooler 26 includes, for example, a double pipe, and exchanges heat between the high-pressure refrigerant flowing through the heat-source-side refrigerant circuit 10b and the intermediate-pressure refrigerant flowing through the first injection circuit 71A. It is. 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 first modification, the liquid refrigerant supercooled by the first subcooler 22 is further subcooled by heat exchange with the intermediate pressure refrigerant in the second subcooler 26. 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 determination of the refrigerant amount in Modification 1 uses 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. Can be done. 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.

Embodiment 2. FIG.
A refrigeration apparatus according to Embodiment 2 of the present invention will be described. FIG. 14 is a refrigerant circuit diagram illustrating a configuration of the refrigeration apparatus according to the present embodiment. In addition, about the component which has the function and effect | action same as Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted. The refrigeration apparatus 1 according to the present embodiment has a configuration in which the second injection circuit 73 is omitted from the refrigeration apparatus 1 according to Modification 1 of Embodiment 1 shown in FIG.

  The first subcooler 22 is a heat exchanger that supercools the liquid refrigerant condensed through the heat source side heat exchanger 23 by heat exchange with the outside air (an example of a cooling fluid).

  The second subcooler 26 includes a cooled side refrigerant flow path 26a connected to the heat source side refrigerant circuit 10b and a cooling side refrigerant flow path 26b connected to the first injection circuit 71A. The high-pressure liquid refrigerant supercooled by the first subcooler 22 flows into the cooled side refrigerant flow path 26 a of the second subcooler 26. The intermediate-pressure two-phase refrigerant (an example of a cooling fluid) that is diverted to the first injection circuit 71A and decompressed by the injection amount adjusting valve 72 flows into the cooling-side refrigerant flow path 26b of the second subcooler 26. The high-pressure liquid refrigerant flowing through the cooled-side refrigerant flow path 26a is further subcooled by heat exchange with the intermediate-pressure two-phase refrigerant flowing through the cooling-side refrigerant flow path 26b.

  In addition, the refrigeration apparatus 1 according to the present embodiment includes temperature sensors 35a, 35b, 35c, 35d, and 35e. The temperature sensor 35a detects the temperature TH1 of the liquid refrigerant that flows out from the receiver 25 and flows into the first subcooler 22. The temperature sensor 35b detects the temperature TH2 of the liquid refrigerant that flows out of the first subcooler 22 and flows into the cooled side refrigerant passage 26a of the second subcooler 26. The temperature sensor 35c detects the temperature TH3 of the liquid refrigerant flowing out of the cooled side refrigerant passage 26a of the second subcooler 26. The temperature sensor 35d detects the temperature of the two-phase refrigerant that flows out of the injection amount adjustment valve 72 and flows into the cooling-side refrigerant channel 26b of the second subcooler 26. The temperature sensor 35 e detects the temperature of the outside air flowing into the first subcooler 22. These temperature sensors 35a, 35b, 35c, 35d, and 35e are configured to output detected temperature information to the heat source side control unit 31 (not shown in FIG. 14).

  Similar to the first embodiment, in the present embodiment, the subcooler (for example, the first subcooler 22, the second subcooler 26, or the first subcooler 22 and the second subcooler 26). The refrigerant amount (for example, shortage of refrigerant amount) is determined using the temperature efficiency of both. The temperature efficiency of the subcooler is the difference between the temperature of the refrigerant flowing into the subcooler and the temperature of the refrigerant flowing out of the subcooler, and the temperature of the refrigerant flowing into the subcooler and the cooling flowing into the subcooler. It is a value divided by the temperature difference from the fluid temperature.

Specifically, the temperature efficiency of the first subcooler 22 is obtained by the following equation (2).
Temperature efficiency of the first subcooler 22 = (TH1-TH2) / (TH1-TH5) (2)

  Here, in the configuration of the present embodiment, since the saturated liquid refrigerant flows into the first subcooler 22, the value of (TH1-TH2) is the degree of supercooling at the outlet of the first subcooler 22. equal.

Further, the temperature efficiency of the second subcooler 26 is obtained by the following equation (3).
Temperature efficiency of second subcooler 26 = (TH2-TH3) / (TH2-TH4) (3)

  As the temperature efficiency of the subcooler, the temperature efficiency of the first subcooler 22, the temperature efficiency of the second subcooler 26, and the temperature efficiency of the first subcooler 22 and the second subcooler 26 can be used. . In the following description, the temperature efficiency of the first supercooler 22 is taken as an example of the temperature efficiency of the supercooler.

  When the refrigerant amount becomes insufficient, the two-phase refrigerant flows into the first subcooler 22 by reducing the excess liquid refrigerant in the receiver 25. In this case, since a part of the amount of heat received from the outside air by the first subcooler 22 is used as the latent heat of condensation of the refrigerant, the temperature efficiency of the first subcooler 22 is reduced. In the present embodiment, as in the first embodiment, this phenomenon is used for determination of the lack of refrigerant.

  FIG. 15 is a diagram illustrating a relationship between the refrigerant amount and the temperature efficiency in the refrigeration apparatus according to the present embodiment. The horizontal axis in FIG. 15 represents the amount of refrigerant charged in the refrigerant circuit 10, and the vertical axis represents the temperature efficiency of the first subcooler 22. As shown in FIG. 15, when the refrigerant amount decreases, the temperature efficiency of the first subcooler 22 decreases. Therefore, when the temperature efficiency of the 1st subcooler 22 is less than the preset determination threshold value (or when it becomes below a determination threshold value), it can determine with the refrigerant | coolant amount being insufficient. . This determination threshold is set so as not to cause erroneous detection or detection delay in consideration of variations in detection accuracy of sensors used for temperature efficiency calculation, for example. Here, the erroneous detection means that it is erroneously determined that the refrigerant is insufficient even though the refrigerant is not insufficient. The detection delay means that the refrigerant shortage determination is delayed or the refrigerant shortage is not determined despite the refrigerant shortage.

  The steady value of the temperature efficiency varies depending on the operation state of the refrigeration apparatus 1 (for example, the condensation temperature, the evaporation temperature, the frequency of the compressor 21). Therefore, when the determination threshold is set to a constant value, the detection accuracy of the refrigerant shortage changes depending on the operation state of the refrigeration apparatus 1. That is, depending on the operating state of the refrigeration apparatus 1, the amount of refrigerant leaked until it is determined that the refrigerant is insufficient is increased.

  FIG. 16 is a diagram showing a relationship among the refrigerant amount, the temperature efficiency, and the operating state of the refrigeration apparatus in the refrigeration apparatus according to the present embodiment. The horizontal axis in FIG. 16 represents the refrigerant amount (kg) charged in the refrigerant circuit 10, and the vertical axis represents the temperature efficiency of the first subcooler 22. In FIG. 16, the temperature efficiency in the operation state 1 where the condensation temperature is low and the evaporation temperature is high is indicated by a solid line, and the temperature efficiency in the operation state 2 where the condensation temperature is high and the evaporation temperature is low is indicated by a broken line. FIG. 17 is a ph diagram in the operating states 1 and 2 shown in FIG. 17A is a ph diagram in the operating state 1 where the condensation temperature is low and the evaporation temperature is high, and FIG. 17B is the p− in the operating state 2 where the condensation temperature is high and the evaporation temperature is low. FIG.

  As shown in FIG. 16, the steady state value of the temperature efficiency in the operation state 1 where the condensation temperature is low and the evaporation temperature is high is lower than the steady state value of the temperature efficiency in the operation state 2 where the condensation temperature is high and the evaporation temperature is low. Yes. This is because the degree of supercooling differs between the operation state 1 (see FIG. 17A) and the operation state 2 (see FIG. 17B). In the operation state 1, since the degree of supercooling is small, the steady value of temperature efficiency is low. On the other hand, in the operating state 2, since the degree of supercooling is large, the steady value of temperature efficiency is high.

  In order to prevent a delay in detection of refrigerant shortage and improve detection accuracy, the determination threshold value may be set to a high value as in the determination threshold value A shown in FIG. However, in this case, since the determination threshold A is higher than the steady value of the temperature efficiency in the driving state 1, a false detection occurs when the driving state changes from the driving state 2 to the driving state 1, for example. In order to prevent erroneous detection, the determination threshold value is set to be lower than the steady-state value of the temperature efficiency in the operation state where the temperature efficiency is the lowest (for example, the operation state 1), as the determination threshold value B shown in FIG. Need to be set. However, in this case, in the operation state 2 where the steady value of the temperature efficiency is high, the detection accuracy of the refrigerant shortage is lowered. For example, when the determination threshold is set to A, a shortage of refrigerant can be detected when the refrigerant amount is reduced to about 23.8 kg in the operation state 2. On the other hand, when the determination threshold is set to B, it is not possible to detect the shortage of refrigerant until the refrigerant amount is reduced to about 22.9 kg in the operation state 2.

  Even when the frequency of the compressor 21 is different, the same problem as described above may occur. In the present embodiment, an inverter compressor driven at a variable frequency can be used as the compressor 21. When the compressor 21 is driven at a high frequency, the amount of refrigerant circulating in the refrigerant circuit 10 increases, so that it is difficult for the first subcooler 22 to supercool the refrigerant. On the other hand, when the compressor 21 is driven at a low frequency, the amount of refrigerant circulating in the refrigerant circuit 10 is reduced, so that the refrigerant is easily supercooled by the first subcooler 22. As a result, when the frequency of the compressor 21 is high, the degree of supercooling in the first subcooler 22 is smaller than when the frequency of the compressor 21 is low, so the steady-state value of temperature efficiency is reduced. To do. For this reason, it is necessary to determine the determination threshold in consideration of a steady value of temperature efficiency when the frequency of the compressor 21 is high. Therefore, when the frequency of the compressor 21 is low, the detection accuracy of the refrigerant shortage is lowered.

  In the present embodiment, in order to solve the above-described problem, the determination threshold is changed based on at least one of the refrigerant condensation temperature and the evaporation temperature in the refrigerant circuit 10. For example, the ROM (for example, the storage unit 3c) of the heat source side control unit 31 stores a map or table that determines the determination threshold based on at least one of the condensation temperature and the evaporation temperature. This map or table is incorporated in software introduced into the heat source side control unit 31, for example.

  FIG. 18 is a diagram illustrating an example of a determination threshold map stored in the ROM of the heat source side control unit 31 of the refrigeration apparatus 1 according to the present embodiment. In the determination threshold map shown in FIG. 18, the temperature efficiency determination threshold is determined based on the condensation temperature and the evaporation temperature. The temperature efficiency determination threshold determined by this determination threshold map decreases as the condensation temperature decreases, and decreases as the evaporation temperature increases. Note that the determination threshold value between the values of the condensation temperature and the evaporation temperature in the determination threshold map is obtained by function interpolation (for example, linear interpolation).

  For example, in step ST5 of FIG. 12, the heat source side control unit 31 changes the determination threshold using the determination threshold map of FIG. 18 before determining whether the refrigerant amount is appropriate. Thereby, the heat-source side control part 31 comes to reduce a determination threshold, so that a condensation temperature becomes low, and to reduce a determination threshold, so that evaporation temperature becomes high. Therefore, the above problems are solved, and the refrigerant amount can be accurately determined.

  In the present embodiment, the temperature efficiency determination threshold is determined based on both the condensation temperature and the evaporation temperature. For example, when the other can be estimated based on one of the condensation temperature and the evaporation temperature. May determine a determination threshold for temperature efficiency based on one of the condensation temperature and the evaporation temperature.

[Modification 2]
Next, a second modification of the present embodiment will be described. In this modification, in order to solve the above-described problem, the determination threshold is changed based on the frequency of the compressor 21 in addition to at least one of the refrigerant condensation temperature and the evaporation temperature in the refrigerant circuit 10.

  FIG. 19 is a diagram illustrating an example of a determination threshold map stored in the ROM of the heat source side control unit 31 of the refrigeration apparatus 1 according to the present modification. In this modification, a plurality of determination threshold maps provided for each frequency of the compressor 21 are stored in the ROM of the heat source side control unit 31. The determination threshold map shown in (a) of FIG. 19 is used when the frequency of the compressor 21 is 50 Hz, and the determination threshold map shown in (b) of FIG. 19 has the frequency of the compressor 21 of 30 Hz. It is used when In the determination threshold map shown in FIG. 19, the temperature efficiency determination threshold is determined based on the condensation temperature, the evaporation temperature, and the frequency of the compressor 21. The temperature efficiency determination threshold determined by the determination threshold map decreases as the frequency of the compressor 21 increases. In the determination threshold map, the determination threshold between the values of the condensation temperature, the evaporation temperature, and the frequency of the compressor 21 is obtained by function interpolation (for example, linear interpolation).

  For example, in step ST5 of FIG. 12, the heat source side control unit 31 changes the determination threshold using the determination threshold map of FIG. 19 before determining the suitability of the refrigerant amount. As a result, the heat source side control unit 31 decreases the determination threshold as the condensing temperature decreases, decreases the determination threshold as the evaporation temperature increases, and increases as the frequency of the compressor 21 increases. Will come down. Therefore, the above problems are solved, and the refrigerant amount can be accurately determined.

[Summary of embodiment]
As described above, the refrigeration apparatus 1 according to the first and second embodiments includes the compressor 21, the condenser (for example, the heat source side heat exchanger 23), the supercooler (for example, the first subcooler 22 or the like). A second subcooler 26), a decompression device (for example, a use-side expansion valve 41), and an evaporator (for example, a use-side heat exchanger 42), a refrigerant circuit 10 for circulating the refrigerant, and a refrigerant in the refrigerant circuit 10 A refrigerant amount determination unit (for example, a heat source side control unit 31) that determines the amount. The supercooler supercools the refrigerant that has passed through the condenser by heat exchange with a cooling fluid (for example, outside air or an intermediate pressure refrigerant). A temperature difference between the temperature of the refrigerant flowing into the subcooler (for example, temperature TH1 detected by the temperature sensor 35a) and the temperature of the refrigerant flowing out of the subcooler (for example, temperature TH2 detected by the temperature sensor 35b) is calculated. The temperature of the refrigerant flowing into the supercooler (for example, the temperature TH1 detected by the temperature sensor 35a) and the temperature of the cooling fluid flowing into the supercooler (for example, the temperature TH5 detected by the temperature sensor 35d) When the value divided by the difference is the temperature efficiency of the subcooler, the refrigerant amount determination unit determines that the refrigerant amount is insufficient when the temperature efficiency falls below the threshold, and condenses the refrigerant in the refrigerant circuit 10. The threshold is changed based on at least one of temperature and evaporation temperature.

  According to this configuration, when the steady value of the temperature efficiency changes based on the condensation temperature and the evaporation temperature, the determination threshold can be changed according to the change of the steady value. Therefore, the refrigerant amount can be accurately determined.

  Further, in the refrigeration apparatus 1 according to Embodiments 1 and 2, the refrigerant amount determination unit may be configured to decrease the threshold value as the condensation temperature decreases. The refrigerant amount determination unit may be configured to increase the threshold value as the condensation temperature increases. According to this configuration, when the condensation temperature is lowered and the steady value of the temperature efficiency is lowered, the determination threshold can be lowered according to the drop of the steady value. Further, according to this configuration, when the condensation temperature rises and the steady value of temperature efficiency rises, the determination threshold can be raised according to the rise of the steady value. Therefore, the refrigerant amount can be accurately determined.

  In the refrigeration apparatus 1 according to Embodiments 1 and 2, the refrigerant amount determination unit may be configured to decrease the threshold value as the evaporation temperature increases. The refrigerant amount determination unit may be configured to increase the threshold value as the evaporation temperature decreases. According to this configuration, when the evaporation temperature rises and the steady value of the temperature efficiency falls, the determination threshold can be lowered according to the fall of the steady value. Further, according to this configuration, when the evaporation temperature is decreased and the steady value of the temperature efficiency is increased, the determination threshold can be increased according to the increase of the steady value. Therefore, the refrigerant amount can be accurately determined.

  In the refrigeration apparatus 1 according to Embodiments 1 and 2, the refrigerant amount determination unit may be further configured to change the threshold based on the frequency of the compressor 21. According to this configuration, when the steady value of the temperature efficiency changes based on the frequency of the compressor 21, the determination threshold can be changed according to the change of the steady value. Therefore, the refrigerant amount can be accurately determined.

  In the refrigeration apparatus 1 according to Embodiments 1 and 2, the refrigerant amount determination unit may be configured to decrease the threshold value as the frequency of the compressor 21 increases. Further, the refrigerant amount determination unit may be configured to increase the threshold as the frequency of the compressor 21 decreases. According to this structure, when the frequency of the compressor 21 increases and the steady value of temperature efficiency falls, the determination threshold value can be lowered according to the fall of the steady value. Moreover, according to this structure, when the frequency of the compressor 21 decreases and the steady value of temperature efficiency rises, a determination threshold value can be raised according to the raise of the steady value. Therefore, the refrigerant amount can be accurately determined.

Other embodiments.
The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, the temperature efficiency determination threshold is changed based on any one of the condensation temperature, the evaporation temperature, and the frequency of the compressor 21, but the present invention is not limited to this. For example, depending on the type of the subcooler (for example, whether it is a double tube heat exchanger, a plate heat exchanger, or an air-cooled heat exchanger), the type of the refrigerant circuit 10 or the compressor 21, the temperature efficiency The steady value may change. In that case, the determination threshold value may be changed based on the type of the subcooler, the refrigerant circuit 10 or the compressor 21. For example, a plurality of determination threshold maps may be prepared in advance, and an appropriate determination threshold map may be selected according to the characteristics of the refrigerant circuit 10.

  In addition, the above embodiments and modifications can be implemented in combination with each other.

  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 , 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 subcooler, 23 heat source side heat exchanger, 24 accumulator, 25 receiver, 26 second subcooler, 26a cooled side refrigerant flow path, 26b cooling side refrigerant flow path, 27 heat source side fan, 28 liquid side closing valve, 29 gas side closing valve, 31 heat source side control section, 32 utilization Side control unit, 33a Suction temperature sensor, 33b Discharge temperature sensor, 33c Suction outside air temperature sensor, 33d Subcooler outlet temperature sensor, 33e Utilization side heat exchanger inlet Temperature sensor, 33f Utilization side heat exchanger outlet temperature sensor, 33g Intake air temperature sensor, 34a Intake pressure sensor, 34b Discharge pressure sensor, 35a, 35b, 35c, 35d, 35e Temperature sensor, 41 Utilization side expansion valve, 42 Utilization 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.

Claims (9)

A refrigerant circuit having a compressor, a condenser, a supercooler, a pressure reducing device, and an evaporator, and circulating the refrigerant;
A refrigerant amount determination unit for determining the refrigerant amount of the refrigerant circuit;
An injection circuit for allowing a part of the refrigerant that has passed through the supercooler to flow into an intermediate pressure part or a suction part of the compressor;
A solenoid valve provided in the injection circuit;
Bei to give a,
The supercooler is for supercooling the refrigerant that has passed through the condenser by heat exchange with a cooling fluid,
The temperature difference between the temperature of the refrigerant flowing into the subcooler and the temperature of the refrigerant flowing out of the subcooler is calculated as the temperature of the refrigerant flowing into the subcooler and the temperature of the cooling fluid flowing into the subcooler. When the value divided by the temperature difference is the temperature efficiency of the supercooler,
The refrigerant amount determination unit
When the operating state of the refrigeration apparatus does not correspond to a preset exception condition for the refrigerant amount determination, perform refrigerant amount determination using the temperature efficiency,
When the temperature efficiency falls below a threshold, it is determined that the refrigerant amount is insufficient,
Based on at least one of the condensation temperature and evaporation temperature of the refrigerant in the refrigerant circuit, the threshold value is changed ,
The exceptional condition includes a case where the solenoid valve is open,
Refrigeration equipment. A refrigerant circuit having a compressor, a condenser, a supercooler, a pressure reducing device, and an evaporator, and circulating the refrigerant;
A refrigerant amount determination unit for determining the refrigerant amount of the refrigerant circuit;
A refrigeration apparatus comprising:
The supercooler is for supercooling the refrigerant that has passed through the condenser by heat exchange with a cooling fluid,
The temperature difference between the temperature of the refrigerant flowing into the subcooler and the temperature of the refrigerant flowing out of the subcooler is calculated as the temperature of the refrigerant flowing into the subcooler and the temperature of the cooling fluid flowing into the subcooler. When the value divided by the temperature difference is the temperature efficiency of the supercooler,
The refrigerant amount determination unit
When the operating state of the refrigeration apparatus does not correspond to a preset exception condition for the refrigerant amount determination, perform refrigerant amount determination using the temperature efficiency,
When the temperature efficiency falls below a threshold, it is determined that the refrigerant amount is insufficient,
The threshold value is configured to be changed based on at least one of a condensation temperature and an evaporation temperature of the refrigerant in the refrigerant circuit,
A refrigeration apparatus configured to lower the threshold as the condensation temperature decreases, or to decrease the threshold as the evaporation temperature increases. A use-side fan that blows air to a use-side heat exchanger that functions as the evaporator during normal operation and functions as the condenser during defrost operation;
The exception condition, the refrigeration apparatus according to claim 1 or 2 including the case where the utilization-side fan is stopped. The refrigeration apparatus according to any one of claims 1 to 3, wherein the exceptional condition includes a pull-down time of the refrigeration apparatus. A heat source side fan that blows air to the heat source side heat exchanger that functions as the condenser during normal operation;
The refrigeration apparatus according to any one of claims 1 to 4, wherein the exceptional condition includes a case where an air volume of the heat source side fan is reduced.   The refrigeration apparatus according to any one of claims 1 to 5, wherein the exceptional condition includes a certain period of time after the compressor is stopped and after the compressor is started. An injection circuit for allowing a part of the refrigerant that has passed through the supercooler to flow into an intermediate pressure part or a suction part of the compressor;
A solenoid valve provided in the injection circuit,
The refrigeration apparatus according to claim 2 , wherein the exceptional condition includes a case where the electromagnetic valve is open. The refrigeration apparatus according to any one of claims 1 to 7 , wherein the refrigerant amount determination unit is further configured to change the threshold based on a frequency of the compressor. The refrigeration apparatus according to claim 8 , wherein the refrigerant amount determination unit is configured to decrease the threshold as the frequency increases.

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