Refrigerant circulating device

Abstract

This refrigerant circulating device is provided with a secondary pipe, a housing, a charging tank, a charging pump, a first connection pipe, a first liquid supply port, and a second liquid supply port. A secondary refrigerant flows through the secondary pipe. The housing accommodates the secondary pipe. The charging tank stores a refrigerant for charging into the secondary pipe. The charging pump is connected to the charging tank and the secondary pipe and pressure-feeds the refrigerant stored in the charging tank toward the secondary pipe. The first connection pipe extends from the charging pump, and the refrigerant from the charging tank flows therethrough. The first liquid supply port is a refrigerant supply port toward the secondary pipe, and the first connection pipe is detachably connected thereto. The second liquid supply port is a refrigerant supply port toward the charging tank, and the first connection pipe is detachably connected thereto. The first connection pipe can be selectively connected to either the first liquid supply port or the second liquid supply port.

Description

Refrigerant circulation device 【0001】 This disclosure relates to a refrigerant circulation device. This application claims priority based on Japanese Patent Application No. 2024-218843 filed in Japan on December 13, 2024, and incorporates its content herein by reference. 【0002】 There is a refrigerant circulation device including a primary pipe through which a primary refrigerant flows, a secondary pipe through which a secondary refrigerant flows, a primary filter connected to the secondary pipe, a secondary filter connected to the secondary pipe, and a liquid injection tank and a liquid injection pump for injecting refrigerant into the secondary pipe (for example, Patent Document 1). 【0003】 U.S. Patent Publication No. 20230147728 【0004】 However, a refrigerant circulation device as described above has room for improvement in terms of enhancing maintainability, for example, facilitating the injection of refrigerant into the secondary pipe. 【0005】 This disclosure has been made in view of the above, and an object thereof is to provide a refrigerant circulation device capable of enhancing maintainability. 【0006】 The refrigerant circulation device of this disclosure includes a secondary pipe, a housing, a liquid injection tank, a liquid injection pump, a first connection pipe, a first liquid supply port, and a second liquid supply port. The secondary pipe allows the secondary refrigerant to flow. The housing houses the secondary pipe. The liquid injection tank stores refrigerant for injecting into the secondary pipe. The liquid injection pump is connected to the liquid injection tank and the secondary pipe, and pumps the refrigerant stored in the liquid injection tank toward the secondary pipe. The first connection pipe extends from the liquid injection pump and allows the refrigerant from the liquid injection tank to flow. The first liquid supply port is a liquid supply port for the refrigerant directed to the secondary pipe, to which the first connection pipe is detachably connected. The second liquid supply port is a liquid supply port for the refrigerant directed to the liquid injection tank, to which the first connection pipe is detachably connected. The first connection pipe is capable of switching the connection destination to either the first liquid supply port or the second liquid supply port. 【0007】 According to the refrigerant circulation device of this disclosure, maintainability can be enhanced. 【0008】Figure 1 is a block diagram showing an example configuration of a refrigerant circulation device according to an embodiment. Figure 2 is a perspective view of the refrigerant circulation device according to an embodiment. Figure 3 is a front view of the refrigerant circulation device according to an embodiment. Figure 4 is a rear view of the refrigerant circulation device according to an embodiment. Figure 5 is a left side view of the refrigerant circulation device according to an embodiment. Figure 6 is a perspective view of the connection of the liquid injection tank and liquid injection pump to the secondary piping side according to an embodiment. Figure 7 is a perspective view of the connection of the liquid injection tank and liquid injection pump to the liquid injection pump side according to an embodiment. Figure 8 is a cross-sectional view showing the inside of the liquid injection tank according to an embodiment. Figure 9 is a perspective view of the level sensor according to an embodiment. 【0009】 The embodiments for implementing the refrigerant circulation device according to this disclosure (hereinafter referred to as "Embodiments") will be described in detail below with reference to the drawings. However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate. In the following embodiments, components that perform the same function are denoted by the same reference numerals, and redundant explanations will be omitted. 【0010】 Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations, for example, in manufacturing accuracy or installation accuracy. 【0011】 Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X, Y, and Z axis directions are sometimes defined, and a Cartesian coordinate system is shown with the positive Z axis pointing vertically upward. 【0012】 Figure 1 is a block diagram showing an example configuration of a refrigerant circulation device 2 according to an embodiment. Components labeled with reference numerals containing "P" (P1 to P10) in Figure 1 are pressure sensors. The pressure sensors detect the pressure of the refrigerant. Components labeled with reference numerals containing "T" (T1 to T5) are temperature sensors. The temperature sensors detect the temperature of the refrigerant. 【0013】Components with the designation "QD" (C1 to C14) are quick-disconnect couplings (hereinafter referred to as "couplings"). Components with the designation "PU" (8, 81) are pumps. Components with the designation "VFD" (D) are variable frequency drivers. 【0014】 The VFD is a control device that controls the operation of the pump. Valves marked with "M" are solenoid valves, while valves without "M" are manual valves. 【0015】 The refrigerant circulation device 2 is a device that circulates primary and secondary refrigerants in order to cool the device to be cooled 102. The device to be cooled 102 is, for example, a heat-generating device such as a CPU (Central Processing Unit). However, the device to be cooled 102 is not limited to a CPU. 【0016】 The refrigerant circulation device 2 includes a primary pipe 3 through which the primary refrigerant flows and a secondary pipe 4 through which the secondary refrigerant flows, both located inside the housing 20. The primary pipe 3 is connected to the cooling tower 101. The cooling tower 101 is a device that cools the primary refrigerant flowing in from the refrigerant circulation device 2 and sends the cooled primary refrigerant back to the refrigerant circulation device 2 for circulation. 【0017】 The secondary piping 4 is connected to the cooling plate 100. The cooling plate 100 is attached to the device to be cooled 102. The refrigerant circulation device 2 delivers secondary refrigerant to the cooling plate 100. Secondary refrigerant that has absorbed heat from the device to be cooled 102 during its passage through the cooling plate 100 flows into the refrigerant circulation device 2. 【0018】 The refrigerant circulation device 2 can be connected to multiple cooling plates 100. Furthermore, the refrigerant circulation device 2 can be connected to multiple cooling target devices 102. Additionally, the refrigerant circulation device 2 can be connected to multiple server racks. 【0019】In this case, the forward path of the secondary piping 4, which carries the secondary refrigerant from the refrigerant circulation device 2 to the server racks, is distributed to multiple server racks and then further distributed to multiple cooling plates 100. The return path of the secondary piping 4, which carries the secondary refrigerant from the server racks to the refrigerant circulation device 2, is collected from multiple cooling plates 100 and then collected from multiple server racks before being connected to the refrigerant circulation device 2. 【0020】 The refrigerant circulation device 2 includes a heat exchanger 5. The heat exchanger 5 is a device that cools the secondary refrigerant by absorbing the heat of the secondary refrigerant flowing in from the cooling plate 100 into the primary refrigerant. The refrigerant circulation device 2 cools the device to be cooled 102 by returning the secondary refrigerant cooled in the heat exchanger 5 to the cooling plate 100. 【0021】 The refrigerant circulation device 2 includes a primary filter 6, a primary flow meter 7, a pump 8, a secondary filter 9, a secondary flow meter 10, an expansion tank 11, and an injection tank 12. A pressure sensor P1 and a temperature sensor T1 are connected to the primary piping 3, which connects the inlet where the primary refrigerant flows in from the cooling tower 101 to the primary filter 6. The pressure sensor P1 is connected to the primary piping 3 via a coupling C1. 【0022】 Furthermore, the primary filter 6 has valve V1 connected to the inlet of the primary refrigerant and valve V2 connected to the outlet of the primary refrigerant. In addition, the primary piping 3 has valve V3 connected to a bypass flow path that bypasses valve V1, the primary filter 6, and valve V2. 【0023】 Furthermore, a pressure sensor P2 is connected to the primary filter 6. In addition, two pipes that connect to the outside of the refrigerant circulation device 2 are connected to the primary filter 6. Valves V4 and V5 are connected to the two pipes. 【0024】 Furthermore, a valve V6 is connected to the primary piping 3 that connects the primary filter 6 and the heat exchanger 5. A coupling C2 for discharging the primary refrigerant to the outside of the refrigerant circulation device 2 is connected to the primary piping 3 that connects the heat exchanger 5 and the primary flow meter 7. 【0025】A pressure sensor P3, a temperature sensor T2, and a coupling C3 are connected to the primary piping 3, which connects the outlet where the primary refrigerant flows out to the cooling tower 101 to the primary flow meter 7. The pressure sensor P3 is connected to the primary piping 3 via coupling C4. Coupling C3 is a maintenance coupling. 【0026】 The primary filter 6 is connected to the primary piping 3 and filters the primary refrigerant flowing through the primary piping 3 to remove foreign matter from the primary refrigerant. If the primary filter 6 becomes clogged or otherwise, the refrigerant pressure detected by the pressure sensor P2 will decrease. 【0027】 Therefore, the refrigerant circulation device 2 can, for example, monitor the pressure downstream of the primary filter 6 using a pressure sensor P2, and if the detected pressure falls below a threshold, it can display a maintenance request on the display operation device 19 (see Figure 3), which will be described later. For example, the pressure sensors P2 are located on the upstream and downstream sides of the primary filter 6, respectively, and detect the differential pressure across the primary filter 6. 【0028】 In addition, the refrigerant circulation device 2 may have a pressure sensor P2A located upstream of the primary filter 6 and a pressure sensor P2B located downstream of the primary filter 6. In this case, the refrigerant circulation device 2 will display a maintenance request notification when the pressure difference detected by the two pressure sensors P2A and P2B exceeds a threshold. 【0029】 When cleaning the primary filter 6, first, valves V1 and V2, which are normally open, are closed, and valve V3 is opened. This allows the refrigerant circulation device 2 to continue circulating the primary refrigerant through a bypass flow path that bypasses the primary filter 6, even while the primary filter 6 is being cleaned. Furthermore, when replacing the primary filter 6, the refrigerant circulation device 2 can also continue circulating the primary refrigerant by using this bypass flow path. 【0030】 Afterward, valves V4 and V5, which are normally closed, are opened, and a portion of the refrigerant W1 is allowed to flow from valve V5 to valve V4 to clean the filter. Once cleaning is complete, valves V4 and V5 are closed, valve V3 is closed, and valves V1 and V2 are opened to return to the normal flow path. 【0031】 The primary flow meter 7 detects the flow rate of the primary refrigerant flowing through the primary piping 3. The primary flow meter 7 outputs the detected flow rate of the primary refrigerant to the display and operation device 19. The display and operation device 19 displays information indicating the operating status of the refrigerant circulation device 2, such as the flow rate of the primary refrigerant. 【0032】 Pump 8 delivers the secondary refrigerant cooled by the heat exchanger 5 toward the cooling plate 100. In the example shown in Figure 1, three pumps 8 are connected in parallel to the secondary piping 4. A variable frequency driver D is connected to each pump 8. The control unit controls the rotation speed of the pumps 8 via the variable frequency driver D, for example, so that the differential pressure between the supply side pressure P7 and the return side P9, P10 of the secondary piping 4 remains constant, or based on the temperature detected by the temperature sensor. 【0033】 The refrigerant circulation device 2 includes a control unit (not shown) that controls the variable frequency driver D. This control unit controls the rotation speed of the pump 8 by the variable frequency driver D, for example, so that the difference between the supply-side pressure of the secondary piping 4 detected by pressure sensors P9 and P10 and the return-side pressure detected by pressure sensors P4 and P5 remains constant, or based on the temperatures detected by temperature sensors T3, T4, and T5. 【0034】 The secondary filter 9 has a valve V10 connected to the inlet of the secondary refrigerant and a valve V11 connected to the outlet of the secondary refrigerant. The secondary piping 4 has a valve V12 connected to a bypass channel that bypasses valve V10, the secondary filter 9, and valve V11. A pressure sensor P8 is also provided near the outlet of the secondary filter 9. As a result, the refrigerant circulation device 2 can continue circulating the secondary refrigerant by using the bypass channel even when the secondary filter 9 is replaced, similar to the primary filter 6. 【0035】 The secondary flow meter 10 is connected to the upstream side of the heat exchanger 5 and detects the flow rate of the secondary refrigerant flowing through the secondary piping 4. The secondary flow meter 10 outputs the detected flow rate of the secondary refrigerant to the display and operation device 19. The display and operation device 19 displays information indicating the operating status of the refrigerant circulation device 2, such as the flow rate of the secondary refrigerant. 【0036】A coupling C7 for discharging secondary refrigerant to the outside of the refrigerant circulation device 2 is connected to the secondary piping 4 that connects the secondary flow meter 10 and the heat exchanger 5. In addition, a temperature sensor T3 and pressure sensors P4 and P5 are connected to the secondary piping 4 that connects the inlet where secondary refrigerant flows in from the cooling plate 100 to the secondary flow meter 10. Pressure sensors P4 and P5 are connected to the secondary piping 4 via couplings C5 and C6. 【0037】 The expansion tank 11 is connected to the secondary piping 4 downstream of the heat exchanger 5. The expansion tank 11 is equipped with a control valve that adjusts the pressure inside the expansion tank 11. The control valve includes a relief valve that releases pressure inside the expansion tank 11 and a diaphragm valve that absorbs pressure fluctuations. The expansion tank 11 adjusts the pressure of the secondary refrigerant flowing through the secondary piping 4 by adjusting the opening of the control valve. 【0038】 The expansion tank 11 is pre-filled with a predetermined pressure. When the refrigerant expands due to heat, the pressure of the secondary refrigerant increases. In this case, the regulating valve located upstream of the expansion tank 11 is opened. 【0039】 At this time, if the pressure of the secondary refrigerant is greater than the sealing pressure of the expansion tank 11, the secondary refrigerant will flow from the secondary piping 4 into the expansion tank 11 until the pressure of the secondary refrigerant becomes equal to the sealing pressure. In this way, the expansion tank 11 can absorb the expansion of the secondary refrigerant, thereby suppressing damage to the secondary piping 4 due to the rise in internal pressure. 【0040】 Furthermore, the expansion tank 11 is positioned downstream of the heat exchanger 5 and upstream of the pump 8. This allows the refrigerant circulation device 2 to adjust the pressure upstream of the pump 8 using the expansion tank 11, even if negative pressure occurs upstream of the pump 8, thereby preventing damage to the pump 8 due to cavitation. 【0041】 Furthermore, in the refrigerant circulation device 2, pressure sensors P9 and P10 and temperature sensors T4 and T5, and coupling C12 are connected to the secondary piping 4 that connects the cooling plate 100 and the secondary filter 9. Pressure sensors P9 and P10 are connected to the secondary piping 4 via couplings C13 and C14. 【0042】 Also, a coupling C12 for discharging the secondary refrigerant to the outside of the refrigerant circulation device 2 is connected to the upstream side of the temperature sensor T4. A pressure sensor P7 is connected to the secondary pipe 4 connecting the secondary flow meter 10 and the pump 8. Valves V7, V8, and V9 are provided on the downstream side of each pump 8. 【0043】 Further, in the refrigerant circulation device 2, a liquid injection pump 81 and a check valve 13 are provided between the liquid injection tank 12 and the pump 8. The check valve 13 is connected to the secondary pipe 4 via a coupling C10. Also, a pressure sensor P6 is connected to the secondary pipe 4 on the upstream side of the check valve 13 and on the downstream side of the expansion tank 11 via a coupling C9. 【0044】 When the amount of the secondary refrigerant flowing through the secondary pipe 4 decreases, the liquid injection pump 81 replenishes the secondary refrigerant from the liquid injection tank 12 to the secondary pipe 4 via the check valve 13. Further, the refrigerant circulation device 2 can suppress the refrigerant pumped from the pump 8 from flowing to the liquid injection tank 12 side and looping within the refrigerant circulation device 2 by closing the check valve 13. Note that the refrigerant circulation device 2 may be configured to include a pressurization tank separately from the liquid injection tank 12 or instead of the liquid injection tank 12. In this case, when the internal pressure of the liquid injection tank 12 decreases, the liquid injection pump 81 presses the secondary refrigerant into the pressurization tank to increase the internal pressure. 【0045】 Further, the refrigerant circulation device 2 includes an air vent valve 15 connected to the secondary pipe 4 on the downstream side of the pump 8. The air vent valve 15 discharges the air that has entered the secondary pipe 4 during the pumping of the pump 8 to the outside of the refrigerant circulation device 2. 【0046】 Further, the refrigerant circulation device 2 includes level sensors 16A and 16B for detecting the amount of the secondary refrigerant in the liquid injection tank 12 and a relief valve 14. When the pressure in the secondary pipe exceeds the threshold value, the refrigerant circulation device 2 causes the relief valve 14 to release the secondary refrigerant from the secondary pipe 4 to the liquid injection tank 12. 【0047】The refrigerant circulation device 2 may be configured such that a relief valve or a pressure regulating valve is further provided on the side of the liquid injection tank 12. In this case, when the pressure in the secondary pipe 4 decreases, the refrigerant circulation device 2 causes the secondary refrigerant to be released from the liquid injection tank 12 into the secondary pipe 4. 【0048】 The level sensors 16A and 16B measure the level of the secondary refrigerant in the liquid injection tank 12. The refrigerant circulation device 2 can stop the operation of the pump 8 when the level of the secondary refrigerant is below the threshold value. 【0049】 Further, when the level of the secondary refrigerant in the liquid injection tank 12 falls below the threshold value, the refrigerant circulation device 2 can be notified, for example, by the display operation device 19 to replenish the secondary refrigerant. 【0050】 Next, referring to FIGS. 2 to 5, an example of the arrangement of the components of the refrigerant circulation device 2 will be described. In the following description, the surface on the positive X-axis side of the refrigerant circulation device 2 is the front surface, the surface on the negative X-axis side is the rear surface, the surface on the positive Y-axis side is the left side surface, the surface on the negative Y-axis side is the right side surface, the surface on the positive Z-axis side is the top surface, and the surface on the negative Z-axis side is the bottom surface. 【0051】 FIG. 2 is a perspective view of the refrigerant circulation device according to the embodiment. FIG. 3 is a front view of the refrigerant circulation device according to the embodiment. FIG. 4 is a rear view of the refrigerant circulation device according to the embodiment. FIG. 5 is a left side view of the refrigerant circulation device according to the embodiment. 【0052】 As shown in FIGS. 2 to 5, the refrigerant circulation device 2 includes a box-shaped housing 20. The wall surface on the front side of the housing 20 is an openable and closable door. Further, a through hole 21 penetrating the top plate is provided on the top surface of the housing 20. 【0053】 The primary pipe 3 and the secondary pipe 4 pass through the through hole 21 and are drawn out from the inside of the housing 20 to the outside. The through hole 21 may be provided on the bottom surface of the housing 20. In this case, the primary pipe 3 and the secondary pipe 4 pass through the through hole 21 on the bottom surface of the housing 20 and are drawn out from the inside of the housing 20 to the outside. 【0054】The housing 20 houses all the components that make up the refrigerant circulation system 2, including the primary piping 3, secondary piping 4, primary filter 6, secondary filter 9, heat exchanger 5, and pump 8. The following describes in detail an example of the arrangement of components inside the housing 20. 【0055】 As shown in Figure 3, the primary filter 6, secondary filter 9, heat exchanger 5, and pump 8 are located on the front side inside the housing 20. This improves accessibility to the primary filter 6, secondary filter 9, heat exchanger 5, and pump 8 of the refrigerant circulation device 2, thereby improving the ease of maintenance by operators. 【0056】 Furthermore, as shown in Figure 4, the connections between the heat exchanger 5 and the primary piping 3 and secondary piping 4, and the connections between the pump 8 and the secondary piping 4 are located inside the housing 20 at locations other than the front side. For example, the connections between the heat exchanger 5 and the primary piping 3 and secondary piping 4, and the connections between the pump 8 and secondary piping 4 are located inside the housing 20 at the rear side of the heat exchanger 5, the bottom and rear sides of the primary filter 6 and secondary filter 9 respectively, and the rear side of the pump 8. This allows the refrigerant circulation device 2 to position the heat exchanger 5 and the pump 8 on the front side, where maintenance work is easily accessible. 【0057】 Furthermore, as shown in Figure 3, the expansion tank 11 and the liquid injection tank 12, which are connected to the secondary piping 4 and store the secondary refrigerant, are located on the front side inside the housing 20. This makes maintenance work on the expansion tank 11 and the liquid injection tank 12 easier, as well as replenishment work on the liquid injection tank 12. 【0058】 Furthermore, the expansion tank 11 and the liquid injection tank 12 are located on the top side of the pump 8. As a result, if air bubbles enter the secondary piping of the refrigerant circulation device 2, the air bubbles will not flow into the pump 8 but will instead flow into the expansion tank 11 and the liquid injection tank 12 (exhaust them), thereby suppressing the inflow of air bubbles into the pump 8. 【0059】Furthermore, the primary filter 6 is located on the top side of the expansion tank 11. In this way, the refrigerant circulation device 2 has the primary filter 6, which requires more maintenance than other components, positioned at a relatively high location, allowing workers to frequently maintain the primary filter 6 in a comfortable posture without bending over. Alternatively, the secondary filter 9 may be located on the top side of the expansion tank 11. In this case, the refrigerant circulation device 2 has the secondary filter 9, which requires more maintenance than the primary filter 6, positioned at a relatively high location, allowing workers to frequently maintain the secondary filter 9 in a comfortable posture without bending over. 【0060】 The liquid injection tank and liquid injection pump according to the embodiment will be described with reference to Figures 6 to 8. Figure 6 is a perspective view of the liquid injection tank and liquid injection pump when connected to the secondary piping side according to the embodiment. Figure 7 is a perspective view of the liquid injection tank and liquid injection pump when connected to the liquid injection pump side according to the embodiment. Figure 8 is a cross-sectional view showing the inside of the liquid injection tank according to the embodiment. 【0061】 As shown in Figure 6, the refrigerant circulation device 2 (see Figure 2) includes an injection tank 12. The injection tank 12 stores refrigerant for injection into the secondary piping 4. The injection tank 12 is connected to the secondary piping 4. The injection tank 12 has a tank section 12a and a connecting pipe 121. By providing the injection tank 12 in this way, the operation of injecting refrigerant into the secondary piping 4 can be easily performed. 【0062】 Furthermore, the refrigerant circulation device 2 is further equipped with an injection pump 81. The injection pump 81 is connected to the injection tank 12 and the secondary piping 4. The injection pump 81 pumps the refrigerant stored in the injection tank 12 towards the secondary piping 4. By providing the injection pump 81 in this way, the refrigerant injection work into the secondary piping 4 can be made even easier. 【0063】The liquid injection pump 81 has a pump section 81a, a first connecting pipe 811, and a second connecting pipe 812. The pump section 81a pumps the refrigerant under pressure. The first connecting pipe 811 extends from the liquid injection pump 81, and refrigerant from the liquid injection tank 12 flows through it. The second connecting pipe 812 detachably connects the liquid injection tank 12 and the liquid injection pump 81. Refrigerant flows from the liquid injection tank 12 to the liquid injection pump 81 through the second connecting pipe 812. 【0064】 The first connecting pipe 811 is connected to the first liquid inlet 821 and the second liquid inlet 823, respectively, via the QD connecting part C11. The QD connecting part C11 protrudes outward from the side of the housing 20 (see Figure 2) when connected to the second liquid inlet 823. This configuration helps to prevent forgetting to disconnect the first connecting pipe 811. In this case, when connected, the door and the QD connecting part C11 interfere with each other, preventing the door from closing, thereby preventing forgetting to disconnect the first connecting pipe 811. 【0065】 The second connecting pipe 812 connects the liquid injection tank 12 and the liquid injection pump 81. Refrigerant flows through the second connecting pipe 812 from the liquid injection tank 12 to the liquid injection pump 81. The second connecting pipe 812 may be detachable from the liquid injection tank 12. 【0066】 The refrigerant circulation device 2 includes a first liquid inlet 821 and a second liquid inlet 823. The first liquid inlet 821 is a refrigerant inlet directed to the secondary piping 4. The first connecting pipe 811 is connected to the first liquid inlet 821. The second liquid inlet 823 is a refrigerant inlet directed to the liquid tank 12. The first connecting pipe 811 is connected to the second liquid inlet 823. As shown in Figures 6 and 7, the first connecting pipe 811 can be switched to connect to either the first liquid inlet 821 or the second liquid inlet 823. In this embodiment, the first liquid inlet 821 and the second liquid inlet 823 are switched by the QD connection part C11 via the first connecting pipe 811, but the embodiment is not limited to this. For example, the first connecting pipe 811 may be connected to the first liquid inlet 821 and the second liquid inlet 823 respectively, and a valve may be provided in the first connecting pipe 811, and the flow path may be changed by switching this valve. 【0067】Furthermore, as shown in Figure 7, a check valve 825 may be placed between the liquid injection pump 81 and the secondary piping 4. The check valve 825 prevents the backflow of refrigerant from the secondary piping 4 to the liquid injection tank 12. This prevents the backflow of refrigerant from the secondary piping 4 to the liquid injection tank 12. 【0068】 Furthermore, the refrigerant circulation device 2 may have manifolds 822 and 824 for switching between the first liquid inlet 821 and the second liquid inlet 823. The first connecting pipe 811 can be switched to connect to either the first liquid inlet 821 or the second liquid inlet 823 via the manifolds 822 and 824. 【0069】 With this configuration, refrigerant can be injected to both the secondary piping 4 and the injection tank 12 simply by switching the connection destination of the first connecting pipe 811, thereby improving maintainability. Furthermore, the fact that the second connecting pipe 812, which connects the injection tank 12 and the injection pump 81, is detachable also improves the maintainability of the secondary piping 4 and other components. In addition, each pipe, such as the first connecting pipe 811, is not routed along the shortest distance but is arranged to take a detour. This helps to suppress interference when inserting or removing other components. 【0070】 Furthermore, as shown in Figure 6, since the second connecting pipe 812 is detachable, by switching the connection destination of the second connecting pipe 812, it becomes possible to inject liquid into the liquid injection tank 12 from the external tank 83 via the second connecting pipe 812. 【0071】 As shown in Figure 8, the liquid injection tank 12 has a refrigerant injection port 84. The injection port 84 is positioned facing upward. The liquid injection tank 12 is positioned, for example, vertically upward. This reduces the risk of refrigerant leakage. The second connecting pipe 812 is inserted into the liquid injection tank 12. In this case, at least one of the liquid injection tank and the liquid injection pump has a holder portion 85 for the second connecting pipe 812. The holder portion 85 fixes the second connecting pipe 812 when it is inserted into the liquid injection tank 12. With this configuration, the positioning of the second connecting pipe 812 becomes easy. It also becomes possible to control the insertion amount of the second connecting pipe 812. 【0072】 Referring to Figure 9, a level sensor according to an embodiment will be described. Figure 9 is a perspective view of a level sensor according to an embodiment. As shown in Figure 9, the refrigerant circulation device 2 includes level sensors 16A and 16B that detect the water level of the refrigerant stored in the liquid injection tank 12. Level sensor 16A is located at the bottom of the liquid injection tank 12 and detects the lower limit of the tank capacity. Level sensor 16A has a fastening member 16Aa and a biasing member 16Ab. Level sensor 16A is fixed to the outer surface of the liquid injection tank 12 by the fastening member 16Aa via the biasing member 16Ab. 【0073】 The level sensor 16B is positioned at the top of the liquid injection tank 12 and detects the upper limit of the tank capacity. The level sensor 16B has a fastening member 16Ba and a biasing member 16Bb. The level sensor 16B is fixed to the outer surface of the liquid injection tank 12 by the fastening member 16Ba via the biasing member 16Bb. With this configuration, the level sensors 16A and 16B can be attached by pressing them against the outer surface of the liquid injection tank 12 via the biasing members 16Ab and 16Bb, making positioning easy. In addition, multiple such level sensors 16A and 16B may be provided to increase redundancy. 【0074】Furthermore, this technology can take the following configuration: (1) A refrigerant circulation device comprising: a secondary pipe through which a secondary refrigerant flows; a housing for housing the secondary pipe; an injection tank for storing refrigerant for injection into the secondary pipe; an injection pump connected to the injection tank and the secondary pipe for pressurizing the refrigerant stored in the injection tank toward the secondary pipe; a first connecting pipe extending from the injection pump through which the refrigerant from the injection tank flows; a first liquid inlet toward the secondary pipe, to which the first connecting pipe is detachably connected; and a second liquid inlet toward the injection tank, to which the first connecting pipe is detachably connected, wherein the first connecting pipe can be switched to connect to either the first liquid inlet or the second liquid inlet. (2) The refrigerant circulation device according to (1), further comprising a second connecting pipe connecting the liquid injection tank and the liquid injection pump, wherein the second connecting pipe is detachable from the liquid injection tank. (3) The refrigerant circulation device according to (1) or (2), wherein the liquid injection tank has a liquid injection port for the refrigerant, and the liquid injection port is positioned upward. (4) The refrigerant circulation device according to (2), wherein the second connecting pipe is inserted into the liquid injection tank, and at least one of the liquid injection tank and the liquid injection pump has a holder portion for fixing the second connecting pipe when it is inserted into the liquid injection tank. (5) The refrigerant circulation device according to any one of (1) to (4), further comprising a manifold for switching between the first liquid inlet and the second liquid inlet, wherein the first connecting pipe switches its connection destination to either the first liquid inlet or the second liquid inlet via the manifold. (6) The refrigerant circulation device according to any one of (1) to (5) above, wherein the first connecting pipe is connected to the first liquid inlet and the second liquid inlet via a QD connecting part, and the QD connecting part protrudes to the outside from the side of the housing while connected to the second liquid inlet. (7) The refrigerant circulation device according to any one of (1) to (6) above, wherein a check valve is disposed between the liquid injection pump and the secondary piping to prevent backflow of refrigerant from the secondary piping to the liquid injection tank.(8) The refrigerant circulation device according to any one of (1) to (7) above, comprising a level sensor for detecting the water level of the refrigerant stored in the liquid injection tank, wherein the level sensor is fixed to the outer surface of the liquid injection tank by a fastening member via a biasing member. 【0075】 Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. 【0076】 2 Refrigerant circulation device 20 Housing 4 Secondary piping 12 Injection tank 821 First inlet 822 Manifold 823 Second inlet 824 Manifold 825 Check valve 81 Injection pump 811 First connecting piping 812 Second connecting piping 84 Injection port 85 Holder section 16A Level sensor 16Aa Fastening member 16Ab Biasing member 16B Level sensor 16Ba Fastening member 16Bb Biasing member C11 QD connection section

Claims

1. A refrigerant circulation device comprising: a secondary pipe through which a secondary refrigerant flows; a housing for the secondary pipe; an injection tank for storing refrigerant to be injected into the secondary pipe; an injection pump connected to the injection tank and the secondary pipe for pressurizing the refrigerant stored in the injection tank toward the secondary pipe; a first connecting pipe extending from the injection pump through which the refrigerant from the injection tank flows; a first liquid inlet toward the secondary pipe, to which the first connecting pipe is detachably connected; and a second liquid inlet toward the injection tank, to which the first connecting pipe is detachably connected, wherein the first connecting pipe can be switched to connect to either the first liquid inlet or the second liquid inlet.

2. The refrigerant circulation device according to claim 1, further comprising a second connecting pipe connecting the liquid injection tank and the liquid injection pump, wherein the second connecting pipe is detachable from the liquid injection tank.

3. The refrigerant circulation device according to claim 1, wherein the liquid injection tank has a liquid injection port for the refrigerant, and the liquid injection port is positioned upward.

4. The refrigerant circulation device according to claim 2, wherein the second connecting pipe is inserted into the liquid injection tank, and at least one of the liquid injection tank and the liquid injection pump has a holder portion for fixing the second connecting pipe when it is inserted into the liquid injection tank.

5. The refrigerant circulation device according to claim 1, further comprising a manifold for switching between the first and second liquid inlet ports, wherein the first connecting pipe switches its connection destination to either the first or second liquid inlet port via the manifold.

6. The refrigerant circulation device according to claim 1, wherein the first connecting pipe is connected to the first liquid inlet and the second liquid inlet via a QD connecting portion, and the QD connecting portion protrudes to the outside from the side of the housing while connected to the second liquid inlet.

7. The refrigerant circulation device according to claim 1, further comprising a check valve positioned between the liquid injection pump and the secondary piping to prevent backflow of refrigerant from the secondary piping to the liquid injection tank.

8. The refrigerant circulation device according to claim 1, further comprising a level sensor for detecting the water level of the refrigerant stored in the liquid injection tank, wherein the level sensor is fixed to the outer surface of the liquid injection tank by a fastening member via a biasing member.

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