Leak detection control device

Abstract

In a method that identifies refrigerant leaks by forming a capacitor near the refrigerant piping and detecting changes in capacitance associated with refrigerant leakage, there is a possibility of false detection of refrigerant leaks due to changes in impedance caused by moisture in the air or rust that forms on metal parts. [Solution] The leak detection control device comprises an oil detector that detects refrigerant oil leaking from the refrigerant circuit of a refrigeration and air conditioning system, and a leak control device that controls the operation of the refrigeration and air conditioning system when refrigerant oil is detected by the oil detector.

Description

Technical Field

[0001] The present disclosure relates to a leakage detection control device that detects leakage from a refrigerant circuit through which a refrigerant flows.

Background Art

[0002] In a refrigeration and air conditioning device, when refrigerant leakage occurs from equipment in the refrigerant circuit, for example, from refrigerant piping, it is necessary to quickly identify the leakage location and take countermeasures. In particular, when using flammable refrigerants such as R32 or propane, this necessity is high.

[0003] Therefore, in Patent Document 1, a capacitor is formed near the refrigerant piping, and by detecting a change in capacitance accompanying refrigerant leakage, the refrigerant leakage location is identified.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in what is described in Patent Document 1, there is a possibility of erroneously detecting refrigerant leakage due to a change in impedance caused by moisture in the air. Also, rust may occur on the metal parts due to moisture, which may also cause false detection.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide a leakage detection control device that can accurately detect leakage from equipment in the refrigerant circuit, particularly from refrigerant piping.

Means for Solving the Problems

[0007] The leak detection control device of this disclosure comprises an oil detector for detecting refrigerant oil leaking from the refrigerant circuit of a refrigeration and air conditioning system, and a leak control device that controls the operation of the refrigeration and air conditioning system when refrigerant oil is detected by the oil detector. [Effects of the Invention]

[0008] According to this disclosure, the possibility of false detection by the oil detector is minimal, and the accuracy of leak detection in refrigerant circuit equipment, particularly in refrigerant piping, is improved. [Brief explanation of the drawing]

[0009] [Figure 1] This is a refrigerant circuit diagram showing the refrigerant flow of the air conditioning system of Embodiment 1. [Figure 2] This is a diagram showing the arrangement of air conditioning equipment within a building according to Embodiment 1. [Figure 3] This is a schematic diagram of the flare section of Embodiment 1. [Figure 4] These are a longitudinal cross-sectional view and an external view of the area around the refrigerant piping in Embodiment 1. [Figure 5] This is a longitudinal cross-sectional view of the area around the refrigerant piping in Embodiment 1. [Figure 6] This is a configuration diagram showing the control configuration for leakage control in Embodiment 1. [Figure 7] This is a flowchart of the leakage processing method for Embodiment 1. [Figure 8] This is an example of the arrangement of the oil detector in Embodiment 2. [Figure 9] This is another example of the arrangement of the oil detector in Embodiment 2. [Modes for carrying out the invention]

[0010] The embodiments for implementing this disclosure will be described with reference to the attached drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are simplified or omitted as appropriate.

[0011] Embodiment 1. Figure 1 is a refrigerant circuit diagram showing the flow of refrigerant in the air conditioning system in Embodiment 1, and Figure 2 is a layout diagram showing the arrangement of the air conditioning system within the building. In this example, the outdoor unit 10 is located on the roof of the building, and the first indoor unit 20, second indoor unit 21, and third indoor unit 22, connected to the outdoor unit 10, are located on the ceiling of the living room, making it a multi-type system.

[0012] The outdoor unit 10 includes a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, a blower fan (not shown), and an outdoor unit control unit 14.

[0013] The compressor 11 draws in low-pressure gaseous refrigerant, compresses it in the compression mechanism, and discharges high-pressure gaseous refrigerant. This gaseous refrigerant is sent to the outdoor heat exchanger 13 or the indoor unit according to the path set by the four-way valve 12. In the outdoor heat exchanger 13, heat exchange takes place between the refrigerant flowing inside and the outside air supplied by the fan.

[0014] The outdoor unit 10 is connected to the first main refrigerant pipe 30a at flare section 15a and to the second main refrigerant pipe 30b at flare section 15b. At flare sections 15a and 15b, as shown in the schematic diagram of the flare section in Figure 3, the male threaded end of the refrigerant pipe of the outdoor unit 10 and the female threaded end of the first main refrigerant pipe 30a and the second main refrigerant pipe 30b are screwed together, connecting the two refrigerant pipes and allowing refrigerant to flow.

[0015] The first main refrigerant pipe 30a is divided into three branch refrigerant pipes 30a1, 30a2, and 30a3 along the way, and these are connected to the first indoor unit 20, the second indoor unit 21, and the third indoor unit 22, respectively, by flare sections 20d, 21d, and 22d. The first indoor unit 20 has a first indoor heat exchanger 20a, a first expansion valve 20b, a fan (not shown), and a first indoor unit control unit 20c. Similarly, the second indoor unit 21 has a second indoor heat exchanger 21a, a second expansion valve 21b, a fan (not shown), and a second indoor unit control unit 21c. The third indoor unit 22 has a third indoor heat exchanger 22a, a third expansion valve 22b, a fan (not shown), and a third indoor unit control unit 22c.

[0016] The second main refrigerant pipe 30b is branched into three branch refrigerant pipes 30b1, 30b2, and 30b3 in the middle, and is connected to the first indoor unit 20, the second indoor unit 21, the third indoor unit 22, and the flare parts 20e, 21e, and 22e respectively.

[0017] Moreover, shut-off valves 40a, 40b, and 40c are arranged in the branch refrigerant pipes 30a1, 30a2, and 30a3, and shut-off valves 41a, 41b, and 41c are arranged in the branch refrigerant pipes 30b1, 30b2, and 30b3. The shut-off valve blocks the flow of refrigerant to the corresponding indoor unit when it is closed.

[0018] Next, the heating operation and the cooling operation in this refrigerant circuit will be described. <Heating Operation> The four-way valve 12 is in a path that connects the discharge side of the compressor 11 and the first main refrigerant pipe 30a. The high-pressure gas refrigerant discharged from the compressor 11 is sent to the first indoor unit 20, the second indoor unit 21, and the third indoor unit 22 via the first main refrigerant pipe 30a, the branch refrigerant pipes 30a1, 30a2, and 30a3.

[0019] [[ID=十七]] In the first indoor unit 20, heat exchange is performed between the gas refrigerant passing through the inside and the indoor air sent by the fan in the first indoor heat exchanger 20a, and the gas refrigerant dissipates heat and becomes a liquid refrigerant. Then, after passing through the first expansion valve 20b, it becomes a low-pressure liquid refrigerant and returns to the outdoor unit 10 via the branch refrigerant pipe 30b1 and the second main refrigerant pipe 30b. The same applies to the second indoor unit 21 and the third indoor unit 22.

[0020] In the outdoor unit 10, the low-pressure liquid refrigerant exchanges heat with the outdoor air sent by the fan in the outdoor heat exchanger 13, and the liquid refrigerant absorbs heat and becomes a low-pressure gas refrigerant. Then, it is sucked into the compressor 11 via the four-way valve 12.

[0021] 第26条<冷房運転> The four-way valve 12 is positioned to connect the discharge side of the compressor 11 to the outdoor heat exchanger 13. The high-pressure gaseous refrigerant discharged from the compressor 11 undergoes heat exchange with the outdoor air supplied by the fan in the outdoor heat exchanger 13. The gaseous refrigerant releases heat and becomes a high-pressure liquid refrigerant, which is then sent to the first indoor unit 20, the second indoor unit 21, and the third indoor unit 22 via the second main refrigerant piping 30b and the branch refrigerant pipings 30b1, 30b2, and 30b3.

[0022] In the first indoor unit 20, the high-pressure liquid refrigerant becomes low-pressure liquid refrigerant after passing through the first expansion valve 20b. In the first indoor heat exchanger 20a, heat exchange takes place between the liquid refrigerant passing through the interior and the indoor air supplied by the fan, causing the liquid refrigerant to absorb heat and become gaseous refrigerant. After that, it returns to the outdoor unit 10 via the branch refrigerant piping 30a1 and the first main refrigerant piping 30a. The same procedure is followed for the second indoor unit 21 and the third indoor unit 22.

[0023] In the outdoor unit 10, the four-way valve 12 is positioned to connect the first main refrigerant pipe 30a to the suction side of the compressor 11, and the low-pressure gaseous refrigerant is drawn into the compressor 11.

[0024] Next, the method for detecting refrigerant leakage in Embodiment 1 will be described. First, in the refrigerant circuit, refrigerant oil is used to lubricate the compression mechanism of the compressor 11. The main types of refrigerant oil are mineral oil and ester oil. Some of this refrigerant oil is discharged from the compressor 11 along with the refrigerant and circulates in the refrigerant circuit. Therefore, in Embodiment 1, a leak of this refrigerant oil is detected. This is because a refrigerant leak occurs wherever refrigerant oil is leaking.

[0025] Figure 4 is a longitudinal cross-sectional view and external view of the area around the refrigerant piping 30 in Figure 1. Figure 5 is a longitudinal cross-sectional view of the area around the refrigerant piping 30 in Figure 1. Figure 6 is a configuration diagram showing the control configuration for leak control. Note that refrigerant piping 30 refers to the first main refrigerant piping 30a, the second main refrigerant piping 30b, and the branch refrigerant pipings 30a1, 30a2, 30a3, 30b1, 30b2, and 30b3, and is used as a general term for these.

[0026] In the diagram, the oil detector 50 consists of an optical fiber cable 51, a light emitter 52 connected to one end thereof, a photodetector 53 connected to the other end, and a communication line 54 used for communication between the light emitter 52 and the photodetector 53. In this configuration, light emitted from the light emitter 52 is received by the photodetector 53 through the optical fiber cable 51. When oil adheres to the optical fiber cable 51, optical transmission loss occurs, and the amount of light reaching the photodetector 53 decreases compared to a normal state. Therefore, by detecting the amount of light received by the photodetector 53, it can be determined that refrigerant and refrigeration oil have leaked from the refrigerant piping and that refrigeration oil has adhered to the optical fiber cable 51.

[0027] The refrigerant piping 30 is covered with a thermal insulation material 31. Furthermore, as shown in the longitudinal cross-sectional view in Figure 4(a), the thermal insulation material 31 has a small notch 31a on the circumferential surface that is in contact with the refrigerant piping 30, extending in the longitudinal direction (the direction in which the refrigerant piping 30 extends), and the optical fiber cable 51 is placed in this portion.

[0028] Furthermore, the oil detectors 50 are arranged in a continuous line along the longitudinal direction in each of the first main refrigerant pipe 30a, the second main refrigerant pipe 30b, and the branch refrigerant pipes 30a1, 30a2, 30a3, 30b1, 30b2, and 30b3, as shown in Figure 5. In other words, the oil detectors 50 are associated with the first main refrigerant pipe 30a, the second main refrigerant pipe 30b, and the branch refrigerant pipes 30a1, 30a2, 30a3, 30b1, 30b2, and 30b3.

[0029] Furthermore, since the refrigerant oil leaking from the refrigerant piping 30 flows downward due to gravity, it is preferable that the optical fiber cable 51 be positioned below the refrigerant piping 30, as shown in Figure 4(a).

[0030] Figure 4(b) is an external view of the thermal insulation material 31 as seen from one side, Figure 4(c) is an external view of the thermal insulation material 31 as seen from the opposite direction to (b), and Figure 4(d) is an external view of the thermal insulation material 31 as seen from a direction 90 degrees from (b) and (c). Here, as shown in Figure 4(b), a solid red line is attached to the outer surface of the thermal insulation material 31 as a marker on the part facing the notch 31a, and a dotted red line is attached on the opposite side. This allows the worker to install the material so that the solid red line is facing downwards, so that the fiber optic cable 51 is positioned below the refrigerant piping 30.

[0031] The leak control device 60 is connected to the photodetector 53 and controls the air conditioning system based on oil detection information received from the photodetector 53, which is determined by the degree of decrease in light intensity. The leak control device 60 is connected to the photodetector 53, shut-off valves 40a, 40b, 40c, 41a, 41b, 41c, outdoor unit control unit 14, and indoor unit control units 20c, 21c, 22c so as to be able to transmit and receive data. The oil detector 50 and the leak control device 60 constitute the leak detection control system.

[0032] Furthermore, the leak control device 60 includes a leak detection unit 61, a shut-off valve control unit 62, an equipment instruction unit 63, and a notification unit 64.

[0033] Next, the procedure for handling leaks of refrigerant oil and refrigerant in the refrigerant piping 30 will be explained based on the leak handling flowchart in Figure 7.

[0034] First, after the air conditioning system is started up, the leak detection unit 61 checks whether it has received oil detection information from the photodetector 53 (step S001).

[0035] In step S001, if oil detection information is received from the photodetector 53, the system identifies which refrigerant piping the photodetector 53 that sent the information corresponds to (step S002). This can be done, for example, by sequentially assigning equipment numbers to the oil detectors 50, storing a correspondence table between these equipment numbers and the refrigerant piping, namely the first main refrigerant piping 30a, the second main refrigerant piping 30b, and the branch refrigerant pipings 30a1, 30a2, 30a3, 30b1, 30b2, and 30b3, and comparing the equipment numbers included in the information transmitted from the photodetector 53 with the correspondence table.

[0036] Next, it is determined whether the corresponding refrigerant piping is a branched refrigerant piping (step S003).

[0037] If step S003 determines that it is a branch refrigerant pipe, the shut-off valve control unit 62 closes the shut-off valve corresponding to the branch refrigerant pipe (step S004). Also, the equipment instruction unit 63 issues a stop instruction to the indoor unit control unit of the indoor unit corresponding to the branch refrigerant pipe (step S005).

[0038] For example, if the leaking pipe was the branch refrigerant pipe 30a1, in step S004, shut-off valves 40a and 41a are closed, and in step S005, a stop command is issued to the first indoor unit control unit 20c, and the first indoor unit 20 stops.

[0039] The reporting unit 64 notifies the administrator of the leak via their smartphone or a monitor located in the control room (step S006). In this way, if the leak is in a branch refrigerant pipe, measures can be taken to prevent refrigerant from flowing through that branch refrigerant pipe, allowing the other indoor units to continue providing air conditioning.

[0040] In step S003, if it is determined that the corresponding refrigerant piping is not a branch refrigerant piping, i.e., the first main refrigerant piping 30a or the second main refrigerant piping 30b, the equipment instruction unit 63 issues a stop instruction to the outdoor unit control unit 14 (step S007) and issues stop instructions to all indoor unit control units 20c, 21c, and 22c (step S008). Furthermore, in this case, since immediate action is necessary, the reporting unit 64 will send emergency information to the administrator's smartphone or to a monitor located in the control room (step S009).

[0041] Normally, oil is not present inside the insulating protective material 31 except when refrigerant oil leaks from the piping. Therefore, the possibility of false detection by the oil detector 50 inside the insulating protective material 31 is almost zero, and the accuracy of leak detection is improved.

[0042] Furthermore, if a leak occurs in a branch refrigerant pipe, only the corresponding branch refrigerant pipe can be closed, allowing air conditioning to continue in the other indoor units.

[0043] In Embodiment 1, the oil detector utilizes the phenomenon that oil adhesion causes optical transmission loss in the optical fiber cable, but other methods may also be used to detect oil.

[0044] Furthermore, although a shut-off valve was provided in the branched refrigerant piping in Embodiment 1, any device that has the function of blocking the flow of refrigerant, i.e., a circuit breaker, does not necessarily have to be composed of a valve.

[0045] Furthermore, the disclosed information is applicable to single-unit air conditioning systems with only one indoor unit. Moreover, it is also applicable to refrigeration systems and other devices that utilize refrigerants to cool objects.

[0046] Furthermore, oil detectors may be placed not only in the refrigerant piping, but also in other locations where refrigerant leaks may occur, such as in the outdoor unit 10 or indoor units 20, 21, and 22, i.e., in the equipment and piping that constitute the refrigerant circuit through which the refrigerant flows, to detect leaks.

[0047] Embodiment 2. In Embodiment 2, instead of a long, thin optical fiber cable, an oil detector having an oil detection band on a flat plate is used.

[0048] Figure 8 shows one example of the configuration of this oil detector. In Figure 8, the oil detector 50 has an oil detection zone 55, a light emitter 52, and a photodetector 53. The light emitter 52 and the photodetector 53 are located in the same housing and are connected by a bus.

[0049] The oil detector 50 is positioned at the bottom of the bend in the refrigerant piping, particularly where the vertical refrigerant piping extending vertically connects to the horizontal refrigerant piping extending horizontally. This is, for example, the connection point in the configuration diagram of Figure 2, where the refrigerant piping descends from the outdoor unit 10 installed on the roof to the living room, and the horizontally extending refrigerant piping connects to the first indoor unit 20, the second indoor unit 21, and the third indoor unit 22 installed on the ceiling.

[0050] Since refrigerant oil leaking in vertical piping flows downwards due to gravity, a leak occurring anywhere in the vertical piping can be detected by placing the oil detection zone 55 below it. Furthermore, a notch 31b is provided in the heat insulating material 31 between the oil detection zone 55 and the refrigerant piping 30, allowing the leaked refrigerant oil to accumulate and making it easier for the refrigerant oil to come into contact with the oil detection zone 55.

[0051] Figure 9 shows another example of the arrangement of this oil detector. In Figure 9, the refrigerant piping extending horizontally is slightly inclined, and notches 31c are formed in the insulating protective material 31 at regular intervals where it contacts the refrigerant piping 30, and the oil detection zones 55 are placed there. Refrigerant oil leaking from the refrigerant piping 30 travels diagonally downwards between the piping 30 and the insulating protective material 31, accumulates in the notches 31c, and can be detected by the oil detection zones 55 placed there. Therefore, if oil is detected, the oil has leaked from the refrigerant piping section located between the detected oil detection zone 55 and the oil detection zone 55 located one diagonally above it, so the location of the leak can also be identified.

[0052] In the case of such a flat oil detection strip 55, it can be inserted into the heat insulating material 31, making installation easier compared to arranging a long fiber optic cable along the refrigerant piping.

[0053] Although preferred embodiments have been described in detail above, the invention is not limited to these embodiments, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of disclosure.

[0054] Furthermore, when referring to the number, quantity, amount, range, etc., of each element in the embodiments, the apparatus of this disclosure is not limited to the referred number unless specifically stated or clearly defined in principle. Also, the structures, etc., described in these embodiments are not necessarily essential unless specifically stated or clearly defined in principle. [Explanation of Symbols]

[0055] 10 Outdoor unit, 11 Compressor, 12 Four-way valve, 13 Outdoor heat exchanger, 14 Outdoor unit control unit, 15a 15b Flare section, 20 First indoor unit, 20a First indoor heat exchanger, 20b First expansion valve, 20c First indoor unit control unit, 20d Flare section, 20e Flare section, 21 Second indoor unit, 21a Second indoor heat exchanger, 21b Second expansion valve, 21c Second indoor unit control unit, 21d Flare section, 21e Flare section, 22 Third indoor unit, 22a Third indoor heat exchanger, 22b Third expansion valve, 22c Third indoor unit control unit, 22d Flare section, 22e Flare section, 30a First main refrigerant piping, 30a1 30a2 30a3 Branch refrigerant piping, 30b Second main refrigerant piping, 30b1 30b2 30b3 Branch refrigerant piping, 31 Insulation protective material, 31a Notch, 31b Notch, 31c Notch, 40a, 40b, 40c, 41a, 41b, 41c shut-off valves, 50 Oil detector, 51 Fiber optic cable, 52 Light emitter, 53 Photodetector, 54 Connecting line, 55 Oil detection zone, 60 Leak control device, 61 Leak detection unit, 62 Shut-off valve control unit, 63 Equipment instruction unit, 64 Reporting Department

Claims

1. A leak detection control device comprising an oil detector for detecting refrigerant oil leaking from the refrigerant circuit of a refrigeration and air conditioning system, and a leak control device for controlling the operation of the refrigeration and air conditioning system when the oil detector detects the refrigerant oil.

2. The leak detection control device according to claim 1, characterized in that the oil detector has an optical fiber cable, and the optical fiber cable is arranged in a heat insulating protective material covering the refrigerant piping.

3. The leak detection control device according to claim 2, characterized in that the thermal insulation protective material has a notch on its inner circumferential surface in contact with the refrigerant piping that extends in the direction of refrigerant flow of the refrigerant piping, and the optical fiber cable is arranged in the notch.

4. The leak detection control device according to claim 3, characterized in that there is a mark on the outer surface of the heat insulating protective material facing the notch.

5. The leak detection control device according to claim 1, characterized in that the oil detector has a flat oil detection strip, and the oil detection strip is arranged in a heat insulating protective material covering the refrigerant piping.

6. The leak detection control device according to claim 5, wherein the refrigerant piping consists of vertical refrigerant piping installed in the vertical direction and horizontal refrigerant piping installed in the horizontal direction, and the oil detection zone is positioned below the bend connecting the vertical refrigerant piping and the horizontal refrigerant piping.

7. The leak detection control device according to claim 6, characterized in that the heat insulating protective material has a notch on its inner circumferential surface that contacts the curved portion, and the oil detection band is positioned in the notch.

8. The leak detection control device according to claim 5, characterized in that the heat insulating protective material has notches at regular intervals along the direction of refrigerant flow of the refrigerant piping on its inner circumferential surface in contact with the refrigerant piping, and the oil detection band is positioned in the notches.

9. The refrigeration and air conditioning system comprises an outdoor unit, a plurality of indoor units, a main refrigerant pipe connected to the outdoor unit, a plurality of branch refrigerant pipes branching from the main refrigerant pipe and connected to the indoor units, and a plurality of circuit breakers provided in each of the branch refrigerant pipes, wherein the oil detectors are arranged corresponding to the main refrigerant pipe and each of the plurality of branch refrigerant pipes, and the leak detection control device, when an oil detector that has detected oil corresponds to one of the branch refrigerant pipes, shuts off the flow of refrigerant with the circuit breaker of the corresponding branch refrigerant pipe, as described in any one of claims 1 to 8.

10. The leak detection control device according to claim 9, characterized in that the leak detection control device stops the operation of the outdoor unit and the indoor unit when the oil detector that has detected oil corresponds to the main refrigerant piping.

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