Method for detecting a refrigerant leak in a refrigerated storage

Abstract

The present disclosure provides a cooling storage capable of easily detecting a refrigerant leakage from a refrigerant circuit and a method for detecting a refrigerant leakage. The cooling storage of the present disclosure includes a refrigerant circuit having a compressor and a cooler, a storage chamber cooled by the cooler, a temperature control sensor detecting a temperature of the storage chamber, and a control unit determining that the refrigerant leaks from the refrigerant circuit when a decrease in a detected value of the temperature control sensor during a reference cooling period is smaller than a reference cooling temperature difference during operation of the compressor.

Description

Technical Field

[0001] This disclosure relates to methods for detecting leaks in cooling storage facilities and refrigerant. Background Technology

[0002] Patent document 1 discloses a display cabinet equipped with a refrigerant leak sensor for detecting refrigerant leakage. The display cabinet has an air path from the suction inlet to the discharge outlet and an evaporator disposed in the air path, with the refrigerant leak sensor disposed below the evaporator.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-085419 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] This disclosure provides a cooling storage tank capable of easily detecting refrigerant leaks from a refrigerant circuit, and a method for detecting refrigerant leaks.

[0008] Methods for solving problems

[0009] This specification contains the full contents of Japanese Patent Application No. 2025-028584, filed on February 26, 2025.

[0010] The cooling storage tank disclosed herein includes: a refrigerant circuit having a compressor and a cooler; a storage chamber cooled by the cooler; a temperature control sensor that detects the temperature of the storage chamber; and a control unit that, during operation of the compressor, determines that refrigerant is leaking from the refrigerant circuit if the decrease in the detected value of the temperature control sensor during a reference cooling period is less than the reference cooling temperature difference.

[0011] The refrigerant leakage detection method disclosed herein uses a control unit installed in a cooling storage tank. During compressor operation, if the decrease in the detected value of a temperature control sensor during a reference cooling period is less than the reference cooling temperature difference, it is determined that refrigerant is leaking from the refrigerant circuit. The cooling storage tank includes: the refrigerant circuit having the compressor and a cooler; a storage chamber cooled by the cooler; and the temperature control sensor detecting the temperature of the storage chamber.

[0012] Invention Effects

[0013] The cooling storage tank and refrigerant leakage detection method disclosed herein can detect refrigerant leaks from the refrigerant circuit regardless of the influence of condensation or frost on the refrigerant sensor. Therefore, refrigerant leaks from the refrigerant circuit can be easily detected. Attached Figure Description

[0014] Figure 1 This is a three-dimensional view of the display case in Implementation Method 1.

[0015] Figure 2 yes Figure 1 Section II.

[0016] Figure 3 This is a block diagram showing the structure of the display case's control system.

[0017] Figure 4 This is a diagram representing an example of a table.

[0018] Figure 5 This is a chart illustrating the shift in the temperature readings of a temperature control sensor within a warehouse.

[0019] Figure 6 It is a flowchart representing the actions of the processor. Detailed Implementation

[0020] (Insights, etc., that form the basis of this disclosure)

[0021] When the inventors conceived of this disclosure, technologies such as cooling storage chambers, including display cases, required the use of refrigerants with minimal environmental impact as the refrigerant filling the refrigerant circuit. Therefore, in this field, the common practice was to design products that incorporate refrigerant sensors, such as contact combustion type or semiconductor type, to detect leaks, given the high prevalence of flammable substances in refrigerants with minimal environmental impact. Under these circumstances, the inventors discovered the following problem: when these refrigerant sensors are installed inside the storage chamber, condensation during defrosting can cause sensor malfunction, or frost can block the sensor from the storage chamber, making it difficult to detect refrigerant leaks. The subject of this disclosure is to address this problem.

[0022] Therefore, this disclosure provides a cooling storage tank capable of easily detecting refrigerant leaks from the refrigerant circuit and a method for detecting refrigerant leaks.

[0023] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, sometimes unnecessary detailed descriptions are omitted. For example, detailed descriptions of matters already known may be omitted, or descriptions of substantially the same structures may be repeated. This is to avoid making the following description too lengthy and to make it easier for those skilled in the art to understand.

[0024] Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure, and are not intended to limit the subject matter of the claims.

[0025] (Implementation Method 1)

[0026] Hereinafter, Embodiment 1 will be described using the accompanying drawings.

[0027] [1-1. Structure]

[0028] [1-1-1. Overall Structure]

[0029] Figure 1 This is a perspective view of display case 1 in implementation method 1. Figure 2 yes Figure 1 The sectional view II in the figure shows the side cross-section of the display case 1. Additionally, the symbol X in the figure indicates the left direction when viewing the display case 1 from the front, the symbol Y indicates the front direction of the display case 1, and the symbol Z indicates the top direction of the display case 1. The display case 1 of this embodiment is installed, for example, in convenience stores, supermarkets, and other similar shops.

[0030] Display case 1 corresponds to an example of the "cooled storage room" in this disclosure.

[0031] The display case 1 has a display chamber 2 with an opening on its front surface. The display chamber 2 is a space for storing merchandise and other items. The display chamber 2 is formed by dividing its left and right sides, top and bottom sides, and rear side by heat-insulating walls 21. Furthermore, the display case 1 has a door 22 that opens and closes the opening on the front surface of the display chamber 2. When the door 22 is closed, it seals the display chamber 2. The door 22 is made of transparent components such as multi-layered glass, for example, so that the interior of the display chamber 2 can be visually observed even when the door 22 is closed.

[0032] Showroom 2 corresponds to an example of “storage room” in this disclosure.

[0033] like Figure 2 As shown, a partition 23 is provided in the showroom 2. The partition 23 is located at the rear of the showroom 2 and has a plate-shaped rear section 24 that is approximately orthogonal to the front-back direction of the display case 1, and a plate-shaped upper section 25 that extends forward from the upper end of the rear section 24. Furthermore, a base plate 26 is provided in the showroom 2. The base plate 26 is located at the lower part of the showroom 2 and is a plate-shaped component that is approximately horizontally positioned. The base plate 26 extends forward from the lower end of the rear section 24. The showroom 2 is divided into a display section 3 and an air conditioning duct section 4 by the partition 23 and the base plate 26.

[0034] Display section 3 is a space within display room 2 where items are arranged. Display section 3 is a portion of display room 2 divided by the front side of the rear panel 24, the lower side of the upper panel 25, and the upper side of the base plate 26. Display section 3 is positioned so that it can be visually observed through an opening on the front surface of display room 2. Multiple shelves 31 for displaying merchandise and other items are provided in display section 3. Shelves 31 are generally horizontal, plate-shaped components.

[0035] The air conditioning duct section 4 is a space that generates cold air for cooling the display section 3. The air conditioning duct section 4 is a part of the display room 2 that is divided by the rear side of the rear section 24, the upper side of the upper section 25, and the lower side of the base plate 26. The air conditioning duct section 4 is connected to the display section 3 via a cold air outlet 41 that opens at the front side of the front end of the upper section 25 and a cold air inlet 42 that opens at the front side of the front end of the base plate 26.

[0036] A cooler 43 and a cooling fan 44 are installed in the air conditioning duct section 4. The cooler 43 mainly functions as an evaporator and is a heat exchanger that cools the showroom 2. The cooler 43 absorbs heat from the air in the air conditioning duct section 4 through its internal refrigerant, thereby cooling the air in the air conditioning duct section 4. Hereinafter, the cooled air will be referred to as cold air. The cooling fan 44 is a blower that circulates air between the showroom 3 and the air conditioning duct section 4. In detail, driven by the cooling fan 44, the air in the showroom 3 flows into the air conditioning duct section 4 through the cold air intake 42, is cooled in the cooler 43, and then returns to the showroom 3 through the cold air outlet 41. That is, each part of the showroom 2 is cooled by the cold air generated by the refrigerant circuit C, which includes the cooler 43, as described later. In addition, a defrosting heater 45 for the cooler 43 is installed in the air conditioning duct section 4.

[0037] A temperature control sensor 46 is installed in the showroom 2. The temperature control sensor 46 is a temperature sensor that detects the internal temperature T of the showroom 2. In this embodiment, the temperature control sensor 46 is installed in the air conditioning duct section 4 in the showroom 2. More specifically, the temperature control sensor 46 is installed in the air conditioning duct section 4 at a position downstream of the cooler 43 in the airflow generated by the air conditioning fan 44.

[0038] Display case 1 has a machinery room 5. Machinery room 5 is a space located below display room 2. Machinery room 5 is separated from display room 2 above by a first heat insulation wall 21A on the lower side of display room 2, and is formed by separating the sides and the bottom with sheet metal or the like. The first heat insulation wall 21A is a heat insulation wall 21 that separates display room 2 and machinery room 5.

[0039] The machine room 5 houses a compressor 51 and a condenser 52. The compressor 51 is a device that compresses and discharges the refrigerant. The condenser 52 is a heat exchanger that allows the refrigerant flowing inside to exchange heat with the air. The condenser 52 primarily liquefies the refrigerant discharged from the compressor 51 by releasing heat to the air.

[0040] Compressor 51, condenser 52, and cooler 43 are connected to refrigerant piping to form refrigerant circuit C. Refrigerant circuit C may include any device such as an expansion valve (not shown). Refrigerant circuit C cools air through cooler 43 to generate cold air. In this embodiment, refrigerant circuit C is filled with a flammable refrigerant such as isobutane (R600a) or propane (R290).

[0041] Furthermore, a condenser fan 53 is provided in the machine room 5. The condenser fan 53 is a blower that supplies air for heat exchange with the refrigerant in the condenser 52. The condenser fan 53 can be, for example, an axial fan or any other type of blower. In this embodiment, an external air intake 54 opening on the front surface of the machine room 5 and an exhaust port 55 opening on the rear surface of the machine room 5 are formed in the machine room 5. The external air intake 54 and the exhaust port 55 are openings that allow ventilation between the interior of the machine room 5 and the exterior of the display case 1. The condenser fan 53 draws external air from the display case 1 into the machine room 5 through the external air intake 54 by blowing air backward, and after heat exchange with the refrigerant in the condenser 52, exhausts the air from the exhaust port 55.

[0042] Furthermore, an external air temperature sensor 56 is installed in the machine room 5. The external air temperature sensor 56 detects the temperature of the external air, i.e., the external air temperature TA. In this embodiment, the external air temperature sensor 56 is installed near the external air intake 54 to detect the external air temperature TA from the external air taken into the machine room 5. In addition, "external air" in this specification refers to the air in the space surrounding the display room 2, which serves as a storage room (e.g., the sales area of ​​a shop).

[0043] [1-1-2. Structure of the Control System]

[0044] Figure 3 This is a block diagram showing the structure of the control system of display case 1. Display case 1 has a control unit 80.

[0045] The control unit 80 is connected to various devices in the display case 1, such as the air conditioning fan 44, heater 45, compressor 51, and condenser fan 53, and controls the operation of each device. Furthermore, the control unit 80 is connected to various sensors, such as the temperature control sensor 46 and the external air temperature sensor 56, and obtains the detection values ​​from each sensor. In this embodiment, however, no contact combustion or semiconductor refrigerant sensor is installed in the display case 1 to detect refrigerant leakage from the refrigerant circuit C.

[0046] The control unit 80 includes a processor 81 and a storage medium 82. The processor 81 is, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).

[0047] Storage medium 82 is composed of, for example, a hard disk, flash memory, or optical disk. Storage medium 82 stores control program 83. Processor 81 performs various processes related to display case 1 by reading and executing control program 83 stored in storage medium 82.

[0048] Storage medium 82 stores table 84. Table 84 is used by processor 81 to determine whether there is a refrigerant leak in refrigerant circuit C. When a refrigerant leak occurs in refrigerant circuit C, the amount of refrigerant in refrigerant circuit C becomes insufficient, and the cooling of display chamber 2 by cooler 43 becomes inadequate. Utilizing this, processor 81 determines that a refrigerant leak has occurred if the decrease in the temperature T detected by temperature control sensor 46 during compressor 51 operation, i.e., during the cooling of display chamber 2 by cooler 43, is insufficient. Specifically, processor 81 uses the decrease in temperature T during the reference cooling period described later during compressor 51 operation for this determination.

[0049] Figure 4 This is a diagram illustrating an example of Table 84. Table 84 contains multiple records R as shown in the rows of Table 84. Each record R contains the value V1 of the starting temperature T1, the value V2 representing the range of the outside air temperature TA, the value V3 of the reference time ts, and the value V4 of the reference cooling temperature difference ΔTs.

[0050] The starting temperature T1 is the temperature used to determine the start time point of the reference cooling period. During the operation of the compressor 51, the processor 81 takes the time point when the temperature sensor 46 detects the temperature T inside the storage compartment and the starting temperature T1 is consistent as the start time point of the reference cooling period.

[0051] The reference time ts is the length of the reference cooling period. That is, the processor 81 takes the period from the point when the temperature sensor 46 detects the temperature T inside the chamber and the temperature T1 is the same as the reference temperature ts as the reference cooling period.

[0052] The reference cooling temperature difference ΔTs is a reference value for the decrease ΔT in the temperature reading of the internal temperature T detected by the temperature control sensor 46 during the reference cooling period. The processor 81 determines that a refrigerant leak has occurred when the decrease ΔT is less than the reference cooling temperature difference ΔTs.

[0053] Furthermore, the temperature T inside the display room 2 when the cooler 43 cools it is affected by the external air temperature TA. For example, when the external air temperature TA is high, the temperature T inside the display room 2 decreases more slowly compared to when the external air temperature TA is low. To reflect this effect, the records R in Table 84 are configured as values ​​V2 that encompass the range of the external air temperature TA.

[0054] Table 84 contains multiple records R with different values ​​V1 for the start temperature T1. In other words, the storage medium 82 of the control unit 80 stores multiple values ​​V1 for the start temperature T1. These multiple values ​​V1 can be arbitrarily set. Furthermore, the values ​​V2 contained in the multiple records R with the same value V1 are set to not overlap. Moreover, the union of the values ​​V2 contained in the multiple records R with the same value V1 is set to include a range encompassing the desired external air temperature TA. Additionally, the value V3 of the reference time ts can be arbitrarily set.

[0055] In contrast, the value V4 of the reference cooling temperature difference ΔTs can be obtained, for example, using data on the shift of the temperature T detected by the temperature control sensor 46 within the storage chamber. The following describes a method for determining the value V4 of the reference cooling temperature difference ΔTs that should be set in a record R using a set of values ​​V1, V2, and V3 set in a record R.

[0056] Figure 5 This is a graph illustrating an example of the shift in the temperature reading T of the storage unit detected by the temperature control sensor 46. It shows the shift in the temperature control sensor 46's reading when the compressor 51, which is currently stopped, starts operating at time t0, while the outside air temperature TA is within the range of value V2. To set the value V4 of the recording R, the conditions need to be adjusted so that the outside air temperature sensor 56's reading of the outside air temperature TA is within the range of value V2 included in the recording R, in order to obtain data on the shift in the temperature reading T of the storage unit.

[0057] exist Figure 5 In the diagram, the vertical axis represents the temperature T inside the storage room, and the horizontal axis represents the time. Figure 5 The solid line curve G1 (cooling limit baseline) represents the temperature T inside the storage room at the cooling limit. The cooling limit refers to the state where it is difficult to cool the display room 2 under conditions where the amount of refrigerant in the refrigerant circuit C is appropriate, but the amount of items placed in the display section 3 is inappropriate, and the door 22 is open, without any refrigerant leakage. Additionally, although it is not used in determining the value V4, it... Figure 5 In the figure, a graph G2, showing the shift of the internal temperature T during standard cooling, is displayed for comparison. Standard cooling refers to a state in which the amount of refrigerant in the refrigerant circuit C, the amount of items placed in the display section 3 are appropriate, and the door 22 is closed, which facilitates the cooling of the display room 2.

[0058] like Figure 5 As shown, before the compressor 51 stops at time t0, the showroom 2 is not cooled, and therefore the temperature T inside the showroom rises over time. Furthermore, the compressor 51 may stop at, for example, during the defrosting operation of the cooler 43, or after the temperature sensor 46 detects that the temperature T inside the showroom has dropped to the set temperature. Additionally, the defrosting operation of the cooler 43 may activate the heater 45, or the compressor 51 may be stopped without the heater 45.

[0059] At time t0, when the control unit 80 starts the compressor 51, the cooler 43 begins cooling the display chamber 2. Therefore, after time t0, the detected value of the internal temperature T decreases over time from the temperature T0 at time t0. However, the decrease in the detected value of the internal temperature T at the cooling limit shown in graph G1 is slower than the decrease in the detected value of the internal temperature T during standard cooling shown in graph G2.

[0060] To set the reference cooling temperature difference ΔTs value V4, firstly, determine the moment t1 when the detected value of the internal temperature T at the cooling limit shown in curve G1 coincides with the predetermined starting temperature T1 value V1. Next, determine the moment t2 after a predetermined reference time ts value V3 has elapsed from the determined moment t1.

[0061] Next, the value of the internal temperature T at the determined cooling limit at the determined time t2 is determined as T2. Then, the value obtained by subtracting the determined value T2 from the value V1 of the starting temperature T1, i.e., the decrease ΔT of the detected value of the internal temperature T, is set as the value V4 of the reference cooling temperature difference ΔTs.

[0062] Thus, in this embodiment, the value V4 of the reference cooling temperature difference ΔTs is set by using the shift of the internal temperature T at the cooling limit. As a result, when determining whether there is a refrigerant leak as described later, if the cooling of the showroom 2 is delayed due to reasons other than refrigerant leakage from the refrigerant circuit C, such as the door 22 being in an open state, false detection of a refrigerant leak can be suppressed.

[0063] Furthermore, as mentioned above, the value V4 is set by using the shift in the detected value of the temperature T inside the storage chamber, thus generating a certain regularity in the data in Table 84.

[0064] For example, as with records R1 and R2, or records R3 and R4, between two records R where values ​​V1 and V3 are equal, the value V4 of records R2 and R4, where V2 is a high temperature, is lower than the value V4 of records R1 and R3, where V2 is a low temperature. Furthermore, as with records R7 and R8, between two records R where values ​​V1 and V4 are equal, the value V3 of record R7, where V2 is a high temperature, is higher than the value V3 of record R8, where V2 is a low temperature. This is because when the value V2, representing the range of external air temperature TA, is high, the internal temperature T is difficult to decrease.

[0065] Furthermore, as with records R1 and R3, or records R2 and R4, between two records R where values ​​V2 and V3 are equal, the value V4 of records R1 and R2, where V1 is at a low temperature, is lower than the value V4 of records R3 and R4, where V1 is at a high temperature. Moreover, as with records R3 and R6, or records R4 and R7, between two records R where values ​​V2 and V4 are equal, the value V3 of records R3 and R4, where V1 is at a low temperature, is higher than the value V3 of records R6 and R7, where V1 is at a high temperature. This is because, under the condition that the value V1 of the initial temperature T1 is already low, the temperature difference between the cooler 43 and the internal temperature T is small, making it difficult to lower the internal temperature T.

[0066] [1-2. Actions]

[0067] The operation of the display case 1 constructed as described above will be explained below.

[0068] Figure 6 This is a flowchart illustrating the actions of processor 81, specifically its actions when determining whether there is a refrigerant leak from refrigerant circuit C. Figure 6 The action is triggered by the processor 81 starting the compressor 51, that is, starting the cooling of the showroom 2.

[0069] First, in step S1, the processor 81 uses the temperature sensor 46 to obtain the detected value of the temperature T inside the warehouse.

[0070] Next, in step S2, the processor 81 determines whether the detection value of the temperature control sensor 46 obtained in step S1 has reached any of the values ​​V1 of the start temperature T1 contained in each record R in Table 84.

[0071] In step S2, if the processor 81 determines that the detection value of the temperature control sensor 46 has not reached any of the multiple values ​​V1 (step S2: no), the processor 81 repeats the action of step S1 again. That is, after the cooling of the display chamber 2 begins, the processor 81 repeatedly performs the actions of steps S1 and S2 until the detection value of the temperature control sensor 46 reaches any one of the starting temperatures T1 due to the decrease in the temperature T inside the chamber.

[0072] In step S2, if the processor 81 determines that the detection value of the temperature control sensor 46 has reached any one of the multiple values ​​V1 (step S2: Yes), the operation of the processor 81 proceeds to step S3. The processor 81 processes the time point at which the detection value of the temperature control sensor 46 has reached any one of the multiple values ​​V1 (step S2: Yes) as the start time point of the reference cooling period. In this embodiment, the processor 81 performs only one cooling operation for the showroom 2. Figure 6 The actions shown. Therefore, in this embodiment, the processor 81 determines the time point at which the detected value of the temperature control sensor 46 initially reaches any one of the multiple values ​​V1 after the compressor 51 starts operating as the start time point of the reference cooling period.

[0073] Next, in step S3, the processor 81 begins to measure the elapsed time since the determination in step S2. In other words, the processor 81 begins to measure the elapsed time from the start time of the reference cooling period.

[0074] In step S4, the processor 81 uses the external air temperature sensor 56 to obtain the detected value of the external air temperature TA. Steps S3 and S4 are executed approximately simultaneously; therefore, in step S4, the processor 81 obtains the detected value of the external air temperature sensor 56 at the start time of the reference cooling period.

[0075] Next, in step S5, the processor 81 uses the value V1 of the starting temperature T1 reached by the temperature control sensor 46 in step S2 and the detection value of the external air temperature sensor 56 obtained in step S3 to determine the reference time ts and the reference cooling temperature difference ΔTs from Table 84.

[0076] Specifically, processor 81 determines that the value V1 in record R of table 84 matches the starting temperature T1 reached by the detection value of temperature sensor 46 in step S2, and that the value V2 includes the record R of the detection value of external air temperature sensor 56 obtained in step S3. Furthermore, in subsequent steps, processor 81 uses the determined values ​​V3 and V4 of record R. In other words, processor 81 changes the value V3 of the reference time ts and the value V4 of the reference cooling temperature difference ΔTs used for determination based on the starting temperature T1 reached by the detection value of temperature sensor 46 and the detection value of external air temperature sensor 56.

[0077] Next, in step S6, the processor 81 determines whether the elapsed time after the start time of the reference cooling period measured in step S3 has reached the value V3 of the reference time ts calculated in step S5.

[0078] In step S6, if the processor 81 determines that the elapsed time has not reached the reference time ts value V3 (step S6: No), the processor 81 performs the determination in step S6 again. If, in step S6, the processor 81 determines that the elapsed time has reached the reference time ts value V3 (step S6: Yes), the processor 81's operation proceeds to step S7. That is, the processor 81 remains in standby until the elapsed time reaches the reference time ts, which is the end time of the reference cooling period, and then performs the operation in step S7 at the end time of the reference cooling period.

[0079] In step S7, the processor 81 uses the temperature sensor 46 to obtain the detected value of the temperature T inside the warehouse.

[0080] Next, in step S8, the processor 81 subtracts the detection value of the temperature control sensor 46 obtained in step S7 from the value V1 of the starting temperature T1 reached by the detection value of the temperature control sensor 46 in step S2, to calculate the decrease in the internal temperature T during the reference cooling period, ΔT. Then, the processor 81 determines whether the calculated decrease ΔT is less than the value V4 of the reference cooling temperature difference ΔTs determined in step S5.

[0081] In step S8, if the processor 81 determines that the decrease in the temperature T inside the chamber during the reference cooling period is less than the value V4 of the reference cooling temperature difference ΔTs (step S8: yes), the operation of the processor 81 proceeds to step S9.

[0082] Then, in step S9, the processor 81 determines that a refrigerant leak is occurring from refrigerant circuit C. After step S9, the processor 81 ends the determination of whether there is a refrigerant leak from refrigerant circuit C. Figure 6 The processor 81 can also notify users and managers of the display case 1 of refrigerant leaks after step S9.

[0083] In step S8, if the processor 81 determines that the decrease in the temperature T inside the chamber during the reference cooling period is not less than the value V4 of the reference cooling temperature difference ΔTs (step S8: no), the operation of the processor 81 proceeds to step S10.

[0084] Then, in step S10, the processor 81 determines that no refrigerant leakage has occurred from refrigerant circuit C. After step S10, the processor 81 ends the determination of whether there is a refrigerant leak from refrigerant circuit C. Figure 6 The action.

[0085] [1-3. Effects, etc.]

[0086] As described above, in this embodiment, the display case 1 includes: a refrigerant circuit C having a compressor 51 and a cooler 43; a display chamber 2 cooled by the cooler 43; a temperature control sensor 46 that detects the internal temperature T, which is the temperature of the display chamber 2; and a control unit 80 that determines that refrigerant is leaking from the refrigerant circuit C when the decrease in the detected value ΔT of the temperature control sensor 46 during the reference cooling period is less than the reference cooling temperature difference ΔTs during the operation of the compressor 51.

[0087] Therefore, refrigerant leaks from refrigerant circuit C can be detected without being affected by condensation or frost on the refrigerant sensor. Thus, refrigerant leaks from refrigerant circuit C can be easily detected. Furthermore, since the detection value of the temperature control sensor 46, which does not detect refrigerant leaks, is used, refrigerant leaks can be easily detected regardless of the location of the leak in refrigerant circuit C.

[0088] In particular, in this embodiment, no contact combustion or semiconductor refrigerant sensor for detecting refrigerant leakage is installed in the display case 1. Therefore, the operation of the processor 81 is not affected by condensation or frost on the refrigerant sensor.

[0089] Furthermore, contact combustion and semiconductor refrigerant sensors may develop errors in their characteristics after coming into contact with leaking refrigerant. Additionally, the lifespan of such refrigerant sensors is generally shorter than that of the display case 1. Therefore, maintenance such as refrigerant sensor calibration and replacement is usually required. In contrast, the display case 1 of this embodiment does not have a refrigerant sensor, thus eliminating the need for refrigerant sensor maintenance and replacement.

[0090] As in this embodiment, the display case 1 may also be configured to include an external air temperature sensor 56 that detects the temperature of the external air, i.e., the external air temperature TA, and the control unit 80 changes the value V4 of the reference cooling temperature difference ΔTs based on the detection value of the external air temperature sensor 56.

[0091] Therefore, the temperature of the external air surrounding showroom 2 can be reflected in the reference cooling temperature difference ΔTs value V4 to determine whether there is a refrigerant leak from refrigerant circuit C. Thus, refrigerant leaks from refrigerant circuit C can be detected easily and accurately.

[0092] In particular, in this embodiment, among the multiple records R with the same values ​​V1 and V3, the value V4 of the reference cooling temperature difference ΔTs in the record R where the value V2, representing the range of the external air temperature TA, is high, is lower than the value V4 of the record R where the value V2 is low. That is, if the external air temperature sensor 56 detects a high value at the beginning of the reference cooling period, the control unit 80 sets the value V4 of the reference cooling temperature difference ΔTs to be lower than the value V4 when the detected value is low. Therefore, the difference in the change of the internal temperature T caused by the value of the external air temperature TA can be reflected in the value V4 of the reference cooling temperature difference ΔTs, and refrigerant leakage from the refrigerant circuit C can be easily and accurately detected.

[0093] As in this embodiment, the control unit 80 may also be configured to change the value V3 of the reference time ts, which is the length of the reference cooling period, based on the detection value of the external air temperature sensor 56.

[0094] Therefore, the ambient air temperature TA around showroom 2 can be reflected in the value V3 of reference time ts, which serves as the length of the reference cooling period, to determine whether there is a refrigerant leak from refrigerant circuit C. Thus, refrigerant leaks from refrigerant circuit C can be detected easily and accurately.

[0095] In particular, in this embodiment, among the multiple records R with the same values ​​V1 and V4, the value V3 of the reference time ts in the record R where the value V2, representing the range of the external air temperature TA, is high, is higher than the value V3 of the record R where the value V2 is low. That is, if the external air temperature sensor 56 detects a high value at the beginning of the reference cooling period, the control unit 80 sets the value V3 of the reference time ts to be higher than the value V3 when the detected value is low. Therefore, the difference in the change of the internal temperature T caused by the value of the external air temperature TA can be reflected in the value V3 of the reference time ts, and refrigerant leakage from the refrigerant circuit C can be easily and accurately detected.

[0096] As in this embodiment, the control unit 80 may also be configured to use the time from the point when the detected value of the temperature control sensor 46 drops to the value V1 of the starting temperature T1 during the operation of the compressor 51, up to the value V3 of the reference time ts, as the reference cooling period.

[0097] Therefore, the condition of the temperature sensor 46's detection value at the start time of the reference cooling period can be made consistent with the value V1 of the start temperature T1. Thus, refrigerant leaks from the refrigerant circuit C can be easily and accurately detected.

[0098] As in this embodiment, the control unit 80 may also be configured to store multiple values ​​V1 of the start temperature T1, and after the compressor 51 starts operating, use the time from the point when the detection value of the temperature control sensor 46 reaches any one of the multiple values ​​V1 of the start temperature T1 to the time when the reference time ts has elapsed as the reference cooling period, and change the reference cooling temperature difference ΔTs according to the start temperature T1 reached by the detection value of the temperature control sensor 46 after the compressor 51 starts operating.

[0099] Therefore, while expanding the range of the internal temperature T of showroom 2 that can be used to determine whether there is a refrigerant leak, the internal temperature T of showroom 2 at the start time of the reference cooling period can be reflected in the reference cooling temperature difference ΔTs to determine whether there is a refrigerant leak from the refrigerant circuit C. Thus, refrigerant leaks from the refrigerant circuit C can be detected easily and accurately.

[0100] In particular, in this embodiment, among the multiple records R with the same values ​​V2 and V3, the value V4 of the reference cooling temperature difference ΔTs in the record R where the starting temperature T1 value V1 is high is higher than the value V4 of the record R where the value V1 is low. That is, when the detection value of the temperature control sensor 46 at the beginning of the reference cooling period (in other words, the value V1 of the starting temperature T1) is high, the control unit 80 sets the value V4 of the reference cooling temperature difference ΔTs to be higher than the value V4 when the detection value is low. Therefore, the difference in the change of the internal temperature T caused by the initial value of the internal temperature T at the beginning of the reference cooling period can be reflected in the value V4 of the reference cooling temperature difference ΔTs, and refrigerant leakage from the refrigerant circuit C can be easily and accurately detected.

[0101] In this embodiment, the refrigerant leakage detection method is based on a control unit 80 installed in the display case 1. If, during the operation of the compressor 51, the decrease in the detected value ΔT of the temperature control sensor 46 during the reference cooling period is less than the reference cooling temperature difference ΔTs, it is determined that the refrigerant is leaking from the refrigerant circuit C. The display case 1 includes: a refrigerant circuit C having a compressor 51 and a cooler 43; a display chamber 2 cooled by the cooler 43; and a temperature control sensor 46 for detecting the temperature of the display chamber 2.

[0102] Therefore, refrigerant leaks from refrigerant circuit C can be detected without being affected by condensation or frost on the refrigerant sensor. Thus, refrigerant leaks from refrigerant circuit C can be easily detected. Furthermore, since the detection value of the temperature control sensor 46, which does not detect refrigerant leaks, is used, refrigerant leaks can be easily detected regardless of the location of the leak in refrigerant circuit C.

[0103] (Other implementation methods)

[0104] As described above, Embodiment 1 has been presented as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this and can be applied to embodiments with modifications, substitutions, additions, omissions, etc. Furthermore, new embodiments can be created by combining the constituent elements described in Embodiment 1 above.

[0105] Therefore, other implementation methods are illustrated below.

[0106] In Embodiment 1, a door-type display case 1 is described as an example of a cooled storage unit. A cooled storage unit only needs to have a storage chamber cooled using a refrigerant circuit C. Therefore, the cooled storage unit is not limited to the door-type display case 1. For example, the cooled storage unit can also be an open display case. Furthermore, the cooled storage unit can also be a cold storage unit or a freezer, etc.

[0107] In the above embodiment, it was described that the external air temperature sensor 56 detects the temperature of the external air introduced into the machine room 5, but this is only one example. The external air temperature sensor 56 only needs to detect the temperature around the display room 2, which serves as a storage room, outside the display case 1. Therefore, for example, in the case of a display case with a separate refrigeration unit, the external air temperature sensor 56 can also be installed on the outside of the display room 2. Furthermore, it was described that the temperature control sensor 46 is installed in the air conditioning duct section 4, but this is only one example. The temperature control sensor 46 only needs to be able to detect the temperature of the display room 2, and for example, it can also be installed in the display section 3.

[0108] In the above embodiment, it is explained that the processor 81 performs only one cooling operation for the showroom 2. Figure 6 The action shown is for determining whether there is a refrigerant leak, but this is just one example. The processor 81 could also be configured to perform multiple cooling operations for a single cooling cycle of the showroom 2. Figure 6 The actions shown.

[0109] In the above embodiment, a refrigerant sensor for detecting refrigerant leakage from refrigerant circuit C was not installed in display case 1, but this is only one example. A refrigerant sensor can also be installed in display case 1. In this case, the reliability of detecting refrigerant leakage from refrigerant circuit C can be improved. However, as in the above embodiment, by adopting a structure without a refrigerant sensor, maintenance and replacement of the refrigerant sensor are unnecessary. Furthermore, refrigerant leakage can be detected without being affected by condensation or frost on the refrigerant sensor.

[0110] In Embodiment 1, the control unit 80 is described as including a processor 81 and a storage medium 82, but this is only one example. The control unit 80 may also use wiring logic that cannot be rewritten. Using wiring logic in the control unit 80 is effective in improving processing speed. Examples of wiring logic include ASICs (Application Specific Integrated Circuits). Furthermore, the control unit 80 may be implemented by combining a processor and wiring logic. Combining a processor and wiring logic to implement the control unit 80 increases the freedom of software design while improving processing speed. Alternatively, the control unit 80 and a circuit with a different function from the control unit 80 may be constructed using a single semiconductor element. Examples of circuits with other functions include A / D / D / A conversion circuits. Furthermore, the control unit 80 may be constructed using a single semiconductor element or multiple semiconductor elements. In the case of multiple semiconductor elements, various controls can be implemented using different semiconductor elements. Additionally, the control unit 80 may be constructed using a structure that includes semiconductor elements and passive components such as resistors or capacitors.

[0111] The flowchart illustrating the implementation method shows steps divided according to the main processing content for ease of understanding. The actions are not limited by the method or name of the division into processing units. Further division into more step units is also possible based on the processing content. Additionally, the steps can be divided in a way that includes more processes within a single step unit. Furthermore, the order of these steps can be appropriately rearranged without affecting the spirit of this disclosure.

[0112] Furthermore, the above-described embodiments are used to illustrate the technology in this disclosure, and therefore, various changes, substitutions, additions, omissions, etc., can be made within the scope of the claims or their equivalents.

[0113] (Postscript)

[0114] The following technology has been disclosed through the above description of the embodiments.

[0115] (Technology 1) A cooling storage tank comprising: a refrigerant circuit having a compressor and a cooler; a storage chamber cooled by the cooler; a temperature control sensor for detecting the temperature of the storage chamber; and a control unit for determining that refrigerant is leaking from the refrigerant circuit when, during operation of the compressor, the decrease in the detected value of the temperature control sensor during a reference cooling period is less than a reference cooling temperature difference.

[0116] Therefore, refrigerant leaks from the refrigerant circuit can be detected without being affected by condensation or frost on the refrigerant sensor. Thus, refrigerant leaks from the refrigerant circuit can be easily detected.

[0117] (Technology 2) A cooling storage tank, comprising an external air temperature sensor for detecting the temperature of external air, wherein the control unit changes the reference cooling temperature difference based on the detected value of the external air temperature sensor.

[0118] Therefore, the temperature of the outside air surrounding the storage compartment can be reflected in the reference cooling temperature difference to determine whether there is a refrigerant leak from the refrigerant circuit. Thus, refrigerant leaks from the refrigerant circuit can be detected easily and accurately.

[0119] (Technology 3) The cooling storage tank according to Technology 2, wherein the control unit changes the length of the reference cooling period based on the detection value of the external air temperature sensor.

[0120] Therefore, the temperature of the outside air surrounding the storage compartment can be reflected in the length of a reference cooling period to determine whether there is a refrigerant leak from the refrigerant circuit. Thus, refrigerant leaks from the refrigerant circuit can be detected easily and accurately.

[0121] (Technology 4) According to Technology 1 or 2, the cooling storage tank, wherein the control unit, during the operation of the compressor, takes the period from the time when the detected value of the temperature control sensor drops to the start temperature until a reference time has elapsed as the reference cooling period.

[0122] This ensures that the temperature sensor reading at the start of the reference cooling period matches the starting temperature. Therefore, refrigerant leaks from the refrigerant circuit can be detected easily and accurately.

[0123] (Technology 5) A cooling storage tank, wherein the control unit stores a plurality of said start temperatures, and after the compressor starts operating, the time from the point when the detection value of the temperature control sensor reaches any one of the plurality of said start temperatures until the time when the reference time has elapsed is taken as the reference cooling period, and the reference cooling temperature difference is changed according to the start temperature reached after the compressor starts operating based on the detection value of the temperature control sensor.

[0124] Therefore, it is possible to expand the temperature range of the storage compartment that can be used to determine whether there is a refrigerant leak, while reflecting the temperature of the storage compartment at the start time of the reference cooling period in the reference cooling temperature difference, to determine whether there is a refrigerant leak from the refrigerant circuit. Thus, refrigerant leaks from the refrigerant circuit can be detected easily and accurately.

[0125] (Technology 6) A method for detecting refrigerant leakage, wherein a control unit installed in a cooling storage chamber determines that refrigerant is leaking from the refrigerant circuit when the decrease in the detected value of the temperature control sensor during a reference cooling period is less than the reference cooling temperature difference during compressor operation, wherein the cooling storage chamber comprises: the refrigerant circuit having the compressor and a cooler; a storage chamber cooled by the cooler; and a temperature control sensor that detects the temperature of the storage chamber.

[0126] Therefore, refrigerant leaks from the refrigerant circuit can be detected without being affected by condensation or frost on the refrigerant sensor. Thus, refrigerant leaks from the refrigerant circuit can be easily detected.

[0127] Industrial availability

[0128] This disclosure can be applied to cooling storage tanks and methods for detecting refrigerant leaks in cooling storage tanks. Specifically, this disclosure can be applied to any type of cooling storage tank, such as door-type or open display cases, cold storage or freezer, and methods for detecting refrigerant leaks in these cooling storage tanks.

[0129] Label Explanation

[0130] 1. Display case (cooled storage room)

[0131] 2. Showroom (Storage Room)

[0132] 3. Display Department

[0133] 4. Air Conditioning Piping Section

[0134] 5 Machine Room

[0135] 21 Insulated Wall

[0136] 21A First Insulation Wall

[0137] 22 doors

[0138] 23 partitions

[0139] 24 Back Face

[0140] 25 upper face

[0141] 26 base plate

[0142] 31 boards

[0143] 41 Airflow outlet

[0144] 42 Cold air intake

[0145] 43 Cooler

[0146] 44 Air Conditioner Fan

[0147] 45 heater

[0148] 46 Temperature Control Sensor

[0149] 51 compressor

[0150] 52 condenser

[0151] 53 Condenser Fan

[0152] 54 External Air Inlet

[0153] 55 exhaust port

[0154] 56 External Air Temperature Sensor

[0155] 72 memory

[0156] 80 Control Department

[0157] 81 processor

[0158] 82 storage media

[0159] 83 Control Program

[0160] Table 84

[0161] C refrigerant circuit

Claims

1. A cooling storage tank, comprising: A refrigerant circuit, which includes a compressor and a cooler; The storage compartment is cooled by the aforementioned cooler; A temperature control sensor detects the temperature of the storage compartment; and The control unit determines that refrigerant is leaking from the refrigerant circuit if, during the operation of the compressor, the decrease in the detected value of the temperature control sensor during the reference cooling period is less than the reference cooling temperature difference.

2. The cooling storage tank according to claim 1, wherein, The cooling storage tank is equipped with an external air temperature sensor to detect the temperature of the outside air. The control unit changes the reference cooling temperature difference based on the detection value of the external air temperature sensor.

3. The cooling storage tank according to claim 2, wherein, The control unit adjusts the length of the reference cooling period based on the detection value of the external air temperature sensor.

4. The cooling storage tank according to any one of claims 1 to 3, wherein, The control unit, during the operation of the compressor, defines the reference cooling period as the time from the point when the detected value of the temperature control sensor drops to the starting temperature until a reference time has elapsed.

5. The cooling storage tank according to claim 4, wherein, The control unit Store multiple of the aforementioned start temperatures. The reference cooling period is defined as the time from the point when the temperature sensor detects that the temperature reaches any one of the plurality of start temperatures after the compressor starts operating, until the reference time has elapsed. The reference cooling temperature difference is adjusted based on the starting temperature reached after the compressor starts operating, as detected by the temperature control sensor.

6. A method for detecting refrigerant leakage, comprising, by means of a control unit installed in a cooling storage tank, determining that refrigerant is leaking from the refrigerant circuit if, during compressor operation, the decrease in the detected value of a temperature control sensor during a reference cooling period is less than the reference cooling temperature difference, wherein... The cooling storage tank includes: the refrigerant circuit having the compressor and the cooler; a storage chamber cooled by the cooler; and the temperature control sensor for detecting the temperature of the storage chamber.

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