A gripping shaft and a gas tightness detection device for a flow battery stack

Abstract

The utility model belongs to the technical field of liquid flow battery energy storage system, concretely relates to a kind of gripping shaft and the air tightness detection device for liquid flow battery stack, gripping shaft includes the shaft shoulder in bottom end, shaft body, the step portion above shaft body and the end portion in top end, the diameter of step portion is less than the diameter of shaft body and less than the diameter of end portion bottom portion.The air tightness detection device for liquid flow battery stack of the utility model can prevent sliding of lifting assembly and stack by the shaft shoulder of gripping shaft, the step portion is used for stable clamping of mechanical arm, and the tapered end portion provides visual identification to realize automated transfer, improve work efficiency.

Description

Technical Field

[0001] This utility model relates to the technical field of flow battery energy storage systems, specifically to a gripping shaft and an airtightness testing device for flow battery stacks. Background Technology

[0002] In a vanadium redox flow battery system, the core components include a stack unit formed by stacking multiple single cells in series with bipolar plates, separators, and electrodes, as well as positive and negative electrolyte storage tanks. If there is leakage in the electrolyte flow channel or electrode cavity of the stack unit, it will lead to electrolyte cross-flow and loss of active materials, which in turn will cause capacity decay and a decrease in charge and discharge efficiency. Therefore, airtightness testing during the production process of the stack unit is an indispensable key process.

[0003] In the existing flow battery stack airtightness testing process, after the stack unit completes the airtightness test, the testing device and the stack unit need to be transferred to the next process manually or with the help of simple tooling. This not only consumes a lot of manpower, but manual placement is also prone to displacement, collision, and even loosening or damage to the stack components, affecting the accuracy of subsequent assembly. In addition, some testing devices that attempt to adapt to robotic arm transfer suffer from slippage and displacement when the robotic arm grasps the stack due to the lack of clear gripping parts, or the gripping parts conflicting with the support structure of the stack unit. This makes it impossible to balance transfer stability and the overall structural integrity of the testing device. At the same time, the robotic arm is difficult to achieve precise positioning through the gripping structure, and additional positioning marks are required, increasing the complexity and cost of the device.

[0004] Therefore, it is necessary to provide a new gripping shaft and an airtightness testing device for flow battery stacks. Utility Model Content

[0005] In view of this, the present invention provides a gripping shaft and an airtightness detection device for flow battery stacks. The shoulder of the gripping shaft can support the components and the stack to prevent slippage, the stepped part is used for stable clamping by the robotic arm, and the conical end provides visual recognition to realize automated transfer and improve work efficiency.

[0006] The technical solution adopted by this utility model to solve its technical problem is: to provide a gripping shaft, including: a shoulder located at the bottom end of the gripping shaft, a shaft body, a stepped portion located above the shaft body, and an end located at the top end, wherein the diameter of the stepped portion is smaller than the diameter of the shaft body and smaller than the diameter of the bottom of the end.

[0007] Furthermore, the stepped portion is located between the shaft body and the end portion.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is: to provide an airtightness testing device for a flow battery stack, including the gripping shaft provided by any of the above solutions.

[0009] Furthermore, the pressure plate assembly includes an upper pressure plate, and the diameter of the shaft body is adapted to the first connecting hole on the lower pad and the second connecting hole on the upper pressure plate.

[0010] Furthermore, the airtightness testing device for the flow battery stack also includes a pad assembly and a pressure plate assembly, with the gripping shaft passing through the pad assembly and the pressure plate assembly.

[0011] Furthermore, the pad assembly includes a lower pad, and the diameter of the shoulder is larger than the diameter of the first connecting hole on the lower pad.

[0012] Furthermore, the pressure plate assembly includes an upper pressure plate, and the diameter of the shaft body is adapted to the first connecting hole on the lower pad and the second connecting hole on the upper pressure plate.

[0013] Furthermore, four gripping shafts are provided, which are arranged symmetrically after passing through the lower pad and the upper pressure plate in sequence.

[0014] Furthermore, the shaft is placed through the first connecting hole on the lower pad and the second connecting hole on the upper pressure plate.

[0015] Furthermore, the height of the shaft is greater than the overall thickness of the pad assembly, the fuel cell unit, and the pressure plate assembly.

[0016] The beneficial effects of this invention are as follows: The gripping shaft and the airtightness testing device for flow battery stacks of this invention include a shoulder at the bottom, a shaft body, a stepped portion above the shaft body, and an end portion at the top. The diameter of the stepped portion is smaller than the diameter of the shaft body and smaller than the diameter of the bottom of the end portion. The gripping shaft of this invention can support the entire assembly of the pad plate assembly, the stack unit, and the pressure plate assembly through the shoulder, preventing components from slipping during gripping. Because the diameter of the stepped portion is smaller than the diameters of the shaft body and the bottom of the end portion, it provides a stable gripping position for the robotic arm gripper, avoiding slippage and displacement, and ensuring gripping reliability. The end portion facilitates recognition by the vision sensor of the automated production line, assisting the robotic arm in quickly calibrating the gripping coordinates, realizing automated transfer of the device and the stack unit without manual handling, significantly improving post-inspection transfer efficiency, and adapting to large-scale production. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is an exploded view of the airtightness testing device and fuel cell unit according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of the pad assembly according to an embodiment of the present utility model;

[0020] Figure 3 This is a partial exploded view of the pad assembly from another perspective according to an embodiment of the present utility model;

[0021] Figure 4 This is a schematic diagram of the pressure plate assembly according to an embodiment of the present utility model;

[0022] Figure 5 This is a schematic diagram of the gripping shaft according to an embodiment of the present invention;

[0023] Figure 6 This is a cross-sectional view of the airtightness testing device, the fuel cell unit, and the worktable according to an embodiment of the present invention;

[0024] Figure 7 This is a cross-sectional view of the airtightness testing device, fuel cell unit, and workbench from another perspective, according to an embodiment of the present invention.

[0025] The component names and their numbers in the diagram are as follows:

[0026] 100 for airtightness testing of flow battery stacks;

[0027] Pad assembly 1, lower pad 11, first connecting part 111, first connecting hole 1111, first positioning hole 112, detection port 113, first solid sealing gasket 12, hollow sealing gasket 13, positioning screw 14, positioning pin 15, limiting shaft hole 151, and gas measurement quick connector 16.

[0028] Pressure plate assembly 2, upper pressure plate 21, second connecting part 211, second connecting hole 2111, second positioning hole 212, second solid sealing gasket 22;

[0029] Grip shaft 3, shoulder 31, shaft body 32, step portion 33, end portion 34;

[0030] Work surface 4, work surface groove 41;

[0031] fuel cell unit 200. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0033] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0034] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0035] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0036] Throughout this specification, reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in some embodiments," or "in some of these embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0037] The present invention provides a description of the airtightness testing device 100 for a flow battery stack. The flow battery stack includes an electrochemical reaction unit formed by stacking multiple single cells through bipolar plates, separators, electrodes, etc. The stack unit 200 of the flow battery has electrolyte inlet and outlet channels distributed on its end face. The electrolyte inlet and outlet channels are key interfaces for realizing the circulation of positive and negative electrolytes, including an inlet for electrolyte inflow and an outlet for electrolyte outflow. The airtightness testing device 100 is used to verify whether there is leakage in the electrolyte channels and electrode cavities of the stack unit 200, so as to avoid electrolyte cross-flow or external leakage affecting battery performance.

[0038] like Figure 1As shown, this embodiment provides an airtightness testing device 100 for a flow battery stack, including a pad assembly 1, a pressure plate assembly 2, and a gripping shaft 3 passing through the pad assembly 1 and the pressure plate assembly 2. The pad assembly 1 and the pressure plate assembly 2 are respectively attached to the two end faces of the stack unit 200. The pad assembly 1 is provided with a detection port 113, which is connected to an external air pressure detection system. The air pressure detection system pressurizes the electrolyte flow channel and electrode cavity of the stack unit 200 through the detection port 113 to form an air pressure difference, thereby detecting the airtightness of the stack unit 200. Among them, the pad assembly 1 is used to achieve precise positioning of the fuel cell stack unit 200, form a sealing fit with the pressure plate assembly 2, and connect to the air pressure detection system to detect the air tightness of the fuel cell stack unit 200; the pressure plate assembly 2 is used to form a sealing fit with the pad assembly 1 to ensure the air tightness of the air tightness test; the gripping shaft 3 is used for the robotic arm to identify and grip, realize the gripping and transfer of the air tightness detection device 100 and the fuel cell stack unit 200.

[0039] In some of these embodiments, such as Figure 2 As shown, the pad assembly 1 includes a lower pad 11, a first solid sealing gasket 12 disposed on the lower pad 11, a hollow sealing gasket 13, a positioning screw 14, and a positioning pin 15 disposed on the positioning screw 14. The lower pad 11 is generally a frame-shaped flat plate with two square openings starting from the center, making the lower pad 11 generally frame-shaped. The size of the lower pad 11 is the same as the size of the fuel cell stack unit 200. The two square openings serve two purposes: firstly, they act as observation ports for the fuel cell stack unit 200 to observe whether the stacked units 200 are flat; secondly, they reduce weight and save costs. Figure 3 As shown, the lower pad 11 includes first connecting portions 111 protruding from both sides of the lower pad 11 and first positioning holes 112 formed in the lower pad 11. Four first connecting portions 111 are provided, each protruding from both sides of the lower pad 11, and each first connecting portion 111 has a first connecting hole 1111 for the gripping shaft 3 to pass through. Four first positioning holes 112 are provided, each located at one of the four corners of the lower pad 11, and their positions correspond to four pre-drilled holes on the fuel cell stack unit 200. The diameter of the first positioning hole 112 is matched with the diameter of the positioning screw 14. A mating groove is formed at the first positioning hole 112 on the side near the fuel cell stack unit 200, and the mating groove is matched with the size of the end of the positioning pin 15, so that the end of the positioning pin 15 is located in the mating groove during installation, thereby ensuring the flatness of the fuel cell stack units 200 during stacking. The test port 113 is located on the lower pad 11, and the position of the test port 113 is aligned with and connected to the test ports of the electrolyte flow channel inlet and outlet on the end face of the fuel cell unit 200.

[0040] In some embodiments, the fuel cell stack 200 has eight electrolyte inlets and outlets on each end face. Two test ports are provided at the electrolyte inlets and outlets on the end face of the fuel cell stack 200, located on the same end face. Similarly, two detection ports 113 are provided, also located on the same end face of the fuel cell stack 200, and are in contact with the lower pad 11. Two hollow sealing gaskets 13 are provided, located at the detection ports 113. A through hole is provided in the center of each hollow sealing gasket 13, allowing only the quick-connect gas meter 16 to connect and communicate with the internal flow channels of the fuel cell stack 200. This seals the gap between the detection port 113 on the lower pad 11 and the test ports at the electrolyte inlets and outlets of the fuel cell stack, thus ensuring the accuracy of the gas measurement results. The quick-connect gas meter 16 is connected to a gas pressure detection system, which can be an existing automatic gas meter. Six first solid sealing gaskets 12 are provided, which are adapted to the positions of other electrolyte inlet and outlet channels on the same end face of the fuel cell unit 200 that are attached to the lower pad 11. Additionally, it should be noted that mating grooves are also provided on the lower pad 11 at positions corresponding to the first solid sealing gaskets 12 and hollow sealing gaskets 13. The depth of the mating grooves is adapted to the elastic compression of the first solid sealing gaskets 12 and hollow sealing gaskets 13. By providing mating grooves, displacement of the first solid sealing gaskets 12 and hollow sealing gaskets 13 can be prevented during installation, thus serving a positioning function. It also allows the compressed first solid sealing gaskets 12 and hollow sealing gaskets 13 to seal the electrolyte inlet and outlet channels of the fuel cell unit 200, while ensuring the flatness of the fuel cell unit 200.

[0041] In some of these embodiments, such as Figure 3 As shown, four positioning screws 14 are provided, the same number as the first positioning holes 112 on the lower pad 11, and the positioning screws 14 are respectively installed through the positioning holes. Figure 6 As shown, a limiting shaft hole 151 is provided at the center of the bottom of the positioning pin 15. The limiting shaft hole 151 is placed through the rod of the positioning screw 14, and the bottom end of the positioning pin 15 is located in the mating groove provided at the first positioning hole 112. The shaft of the positioning pin 15 is placed through the four holes pre-drilled on the fuel cell stack unit 200. By cooperating with the positioning screw 14 and the positioning pin 15, the connection strength of the overall structure is ensured and it is not easy to loosen. By setting the positioning pin 15, displacement during the assembly of the fuel cell stack unit 200 is prevented. When it is necessary to separate the lower pad 11 from the fuel cell stack unit 200, it is only necessary to separate the rod of the positioning screw 14 from the limiting shaft hole 151 of the positioning pin 15.

[0042] In some of these embodiments, such as Figure 4As shown, the pressure plate assembly 2 includes an upper pressure plate 21 and a second solid sealing gasket 22 disposed on the upper pressure plate 21. The upper pressure plate 21 is generally a frame-shaped flat plate with two square openings at the center, making it generally frame-shaped. The size of the upper pressure plate 21 is the same as the size of the fuel cell stack unit 200. The two square openings serve as observation ports for the fuel cell stack unit 200 to observe whether the stacked units 200 are flat, and also reduce weight and save costs. The upper pressure plate 21 includes second connecting portions 211 protruding from both sides of the upper pressure plate 21 and second positioning holes 212 formed on the upper pressure plate 21. Four second connecting portions 211 are provided, protruding from both sides of the upper pressure plate 21 and adapted to the positions of the first connecting portions 211 on the lower pad plate 11. The second connecting portions 211 have second connecting holes 2111 for the gripping shaft 3 to pass through. Four second positioning holes 212 are provided, respectively opened at the four corners of the upper pressure plate 21. The positions of the second positioning holes 212 correspond to the positions of the first positioning holes 112 and the four holes pre-opened on the fuel cell stack unit 200. The diameter of the second positioning holes 212 is adapted to the diameter of the positioning pin 15 on the pad assembly 1. The positioning pin 15 first passes through the pre-opened hole on the fuel cell stack unit 200, and then passes through the second positioning holes 212 of the upper pressure plate 21, thereby realizing the positioning screw 14 and the positioning pin 15 to position and fix the lower pad 11, the fuel cell stack unit 200 and the upper pressure plate 21.

[0043] In some embodiments, eight second solid sealing gaskets 22 are provided, corresponding to the eight electrolyte inlet and outlet positions on the end face of the fuel cell unit 200 that are attached to the upper pressure plate 21. Additionally, it should be noted that a mating groove is provided on the upper pressure plate 21 at the position corresponding to the second solid sealing gasket 22. The depth of the mating groove is adapted to the elastic compression of the second solid sealing gasket 22. By providing the mating groove, displacement of the second solid sealing gasket 22 can be prevented during installation, serving a positioning function. It also allows the compressed second solid sealing gasket 12 to seal the electrolyte inlet and outlet of the fuel cell unit 200, while ensuring the flatness of the fuel cell unit 200.

[0044] In some embodiments, four gripping shafts 3 are provided, symmetrically arranged after passing through the lower pad 11 and the upper pressure plate 12 in sequence, and the gripping shafts 3 correspond to the positions of the first connecting hole 1111 and the second connecting hole 2111, respectively. Figure 5As shown, the gripping shaft 3 passes sequentially through the first connecting hole 1111 on the lower pad 11 and the second connecting hole 2111 on the upper pressure plate 21. The gripping shaft 3 includes a shoulder 31 at the bottom, a shaft body 32, a stepped portion 33 above the shaft body, and an end portion 34 at the top. The shoulder 31 is located at the bottom of the gripping shaft 3. The shoulder 31 is approximately disc-shaped, and its diameter is larger than the diameter of the first connecting hole 1111 on the lower pad 11. The shoulder 31 serves as the bottom support section of the gripping shaft 3, used to support the entire pad assembly 1, the fuel cell stack unit 200, and the pressure plate assembly 2, preventing the components from slipping during gripping. The shoulder 31 is located below the lower pad 11. Since the pad assembly 1, the fuel cell stack unit 200, and the pressure plate assembly 2 are all placed on the workbench 4 during airtightness testing, as... Figure 7 As shown, a tabletop slot 41 is provided on the worktable 4 at a corresponding position. The size of the tabletop slot 41 is adapted to the size of the shaft shoulder 31, so that the shaft shoulder 31 can be placed in the tabletop slot, thereby ensuring that the entire pad assembly 1, the fuel cell stack unit 200 and the pressure plate assembly 2 are placed flat. The diameter of the shaft body 32 is adapted to the first connecting hole 1111 on the lower pad 11 and the second connecting hole 2111 on the upper pressure plate 21, so as to avoid skewing when the shaft 3 is installed. The shaft body 32 is placed through the first connecting hole 1111 on the lower pad 11 and the second connecting hole 2111 on the upper pressure plate 21, and the height of the shaft body 32 is greater than the overall thickness of the pad assembly 1, the fuel cell stack unit 200 and the pressure plate assembly 2. The diameter of the stepped portion 33 is smaller than the diameter of the shaft body 32, and the diameter of the stepped portion 33 is also smaller than the diameter of the bottom of the end portion 34. The stepped portion 33 is located between the shaft body 32 and the end portion 34. The stepped portion 33 is used to adapt to the gripper part of the robotic arm, making it convenient for the robotic arm gripper to clamp the stepped portion. The stepped structure of the stepped portion 33 makes the contact of the robotic arm gripper more stable, avoiding slippage and displacement during gripping, and improving the reliability of automated operation. The end portion 34 is roughly tapered, and the diameter of the bottom of the end portion 34 is larger than the diameter of the stepped portion 33. The end portion 34 is located at the top of the gripping shaft 3. The end portion 34 is used to provide clear recognition marks for the vision sensors on the automated production line, thereby facilitating the positioning of the robotic arm before gripping.

[0045] The assembly process of the airtightness testing device 100 for a flow battery stack of this utility model is as follows: First, align the shoulder 31 of the gripping shaft 3 with the table slot 41 on the worktable 4, and lower the gripping shaft 3 vertically until the shoulder 31 is fully embedded in the table slot 41. At this time, the shaft body 32 of the gripping shaft 3 is in a vertical state. Next, first, embed the six first solid sealing gaskets 12 into the mating grooves of other electrolyte flow channel inlets and outlets on the same end face of the corresponding stack unit 200 on the lower pad 11. Then, embed the two hollow sealing gaskets 13 into the mating grooves of the corresponding detection ports 113 on the lower pad 11, ensuring that the sealing gaskets are completely in contact with the inner wall of the mating groove. Then, take four positioning screws 14 and place them through the four first positioning holes 112 from the bottom of the lower pad 11. Finally, align the limiting shaft holes 151 of the four positioning pins 15 with the positioning screws. The 14 rods are pressed vertically downwards until the end of the positioning pin 15 is fully embedded in the mating groove of the first positioning hole 112, completing the pre-assembly of the pad assembly 1. Then, the pre-assembled pad assembly 1 is placed above the workbench 4, so that the four first connecting holes 1111 on the first connecting parts 111 on both sides of the lower pad 11 are aligned with the shafts 32 of the four gripping shafts 3, allowing the shafts 32 to pass through the first connecting holes 1111 until the bottom surface of the lower pad 11 is in contact with the surface of the workbench 4. The fuel cell stack unit 200 is placed above the pad assembly 1, so that the four preset holes on the end face of the fuel cell stack unit 200 are aligned with the shafts of the four positioning pins 15, and the bottom surface of the fuel cell stack unit 200 is in contact with the top surface of the lower pad 11, so that the two electrolyte flow channel inlet and outlet test ports of the fuel cell stack unit 200 are in contact with the two detection ports 113 on the lower pad 11. With precise alignment and interconnection, the other six electrolyte flow channel inlets and outlets are fitted one by one with the six first solid sealing gaskets 12, ensuring that the gas path can be normally connected during subsequent gas testing and that non-test ports can be effectively sealed; then, the eight second solid sealing gaskets 22 are embedded into the mating grooves on the upper pressure plate 21, and the pressure plate assembly 2 is placed above the fuel cell stack unit 200, so that the four second positioning holes 212 of the upper pressure plate 21 are aligned with the shafts of the four positioning pins 15, and the four second connecting holes 2111 are aligned with the shafts 32 of the four gripping shafts 3, so that the shafts of the positioning pins 15 are inserted into the second positioning holes 212 and the shafts 32 of the gripping shafts 3 are inserted into the second connecting holes 2111, until the bottom surface of the upper pressure plate 21 is in contact with the top surface of the fuel cell stack unit 200, and the second solid sealing gaskets 22 are tightly fitted with the electrolyte flow channel inlets and outlets on the other end face of the fuel cell stack unit 200, thus achieving overall sealing and positioning of the pad assembly 1, the fuel cell stack unit 200 and the pressure plate assembly 2;Because the hollow sealing gasket 13 has a through hole in the center, only the quick-connect gas connectors 16 are allowed to be connected. One end of each of the two quick-connect gas connectors 16 is aligned with one of the two detection ports 113 on the lower pad 11. Ensure there is no gap between the quick-connect gas connectors 16 and the detection ports 113 to prevent gas leakage. Connect the pipeline of the external air pressure detection system to the other end of the quick-connect gas connectors 16. Start the air pressure detection system. The system fills the electrolyte flow channel and electrode cavity of the fuel cell unit 200 with gas through the quick-connect gas connectors 16 and the detection ports 113 to create a pressure difference. Real-time monitoring of pressure changes determines whether the airtightness of the fuel cell unit 200 is qualified. Finally, after the airtightness test is completed, the robotic arm on the automated production line is started. The robotic arm uses a vision sensor to identify the tapered end 34 at the top of the gripping shaft 3. After calibrating the gripping position, the gripper holds the stepped part 33 of the gripping shaft 3 and lifts the gripping shaft 3 upwards. At this time, the shoulder 31 of the gripping shaft 3 is disengaged from the worktable surface 4. The tabletop slot 41 causes the pad assembly 1, fuel cell stack unit 200, and pressure plate assembly 2 to rise as a whole. The robotic arm then transfers the entire assembly to the next process along a preset path, completing the entire assembly and testing process.

[0046] The airtightness testing device 100 for flow battery stacks of this utility model includes a pad assembly 1, a pressure plate assembly 2, and a gripping shaft 3 passing through the pad assembly 1 and the pressure plate assembly 2. The pad assembly 1 and the pressure plate assembly 2 are respectively attached to the two end faces of the stack unit. The pad assembly 1 includes a lower pad 11, a first solid sealing gasket 12 and a hollow sealing gasket 13 disposed on the lower pad 11, a positioning screw 14, and a positioning pin 15 disposed on the positioning screw 14. A detection port 113 is opened on the lower pad 11. The pressure plate assembly 2 includes an upper pressure plate 21 and a second solid sealing gasket 22 disposed on the upper pressure plate 21. The gripping shaft 3 includes a shoulder 31 located at the bottom end, a shaft body 32, a step portion 33 located above the shaft body 32, and an end portion 34 located at the top end. The diameter of the step portion 33 is smaller than the diameter of the shaft body 32 and smaller than the diameter of the bottom of the end portion 34. The end portion 34 is approximately tapered. This utility model relates to an airtightness testing device 100 for flow battery stacks. Through the engagement of the positioning screws 14 and positioning pins 15 in the pad assembly 1 with their corresponding holes, the device precisely limits the relative positions of the stack unit, pad assembly 1, and pressure plate assembly 2, preventing displacement or misalignment during assembly. This ensures the flatness of the fit between the two end faces of the stack unit and the pad assembly 1 and pressure plate assembly 2, providing a stable benchmark for subsequent airtightness testing and reducing testing errors caused by positioning deviations. The first solid sealing gasket 12 seals the electrolyte flow channel inlet and outlet on the corresponding end face of the stack unit (excluding the test port), the hollow sealing gasket 13 seals the gap between the test port 113 and the test port of the stack unit, and the second solid sealing gasket 22 seals all electrolyte flow channel inlets and outlets on the other end face of the stack unit. This prevents external gas infiltration or internal test gas leakage, ensuring a stable pressure difference is formed when the pressure testing system pressurizes the electrolyte flow channel and electrode cavity of the stack unit through the test port 113, accurately determining whether the stack unit is airtight. The gripping shaft 3 has a shoulder 31 that can support the pad assembly 1, the fuel cell stack unit 200, and the pressure plate assembly 2 as a whole, preventing the components from slipping during gripping. The stepped part 33, because its diameter is smaller than that of the shaft body 32 and the bottom diameter of the end 34, can provide a stable gripping position for the robotic arm gripper, avoiding slippage and displacement during gripping and ensuring gripping reliability. The tapered end 34 is easy for the vision sensor of the automated production line to recognize, assisting the robotic arm to quickly calibrate the gripping coordinates, realizing the automated transfer of the device and the fuel cell stack unit without manual handling, greatly improving the transfer efficiency after inspection and adapting to the needs of large-scale production. The gripping shaft 3 passes through the pad assembly 1 and the pressure plate assembly 2, which can further constrain the relative positions of the three and enhance the overall structural stability. In addition, the lower pad 11 and the upper pressure plate 21 are respectively attached to the two end faces of the fuel cell stack unit, and together with the through support of the gripping shaft 3, it can ensure that the entire device will not deform or loosen due to air pressure or slight external vibration during the inspection process, ensuring the stability of the inspection process.

[0047] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A gripping shaft, characterized in that, include: The gripping shaft includes a shoulder at the bottom, a shaft body, a stepped portion above the shaft body, and an end portion at the top, wherein the diameter of the stepped portion is smaller than the diameter of the shaft body and smaller than the diameter of the bottom of the end portion.

2. The grasping shaft of claim 1, wherein, The stepped portion is located between the shaft body and the end.

3. A device for airtightness testing of flow battery stacks, characterized in that, The airtightness testing device for flow battery stacks includes the gripping shaft as described in any one of claims 1 to 2.

4. The airtightness testing device for flow battery stacks according to claim 3, characterized in that, The airtightness testing device for flow battery stacks further includes a pad assembly and a pressure plate assembly, with the gripping shaft passing through the pad assembly and the pressure plate assembly.

5. The airtightness testing device for a flow battery stack according to claim 4, characterized in that, The pad assembly includes a lower pad, and the diameter of the shoulder is larger than the diameter of the first connecting hole on the lower pad.

6. The airtightness testing device for a flow battery stack according to claim 5, characterized in that, The pressure plate assembly includes an upper pressure plate, and the diameter of the shaft body is adapted to the first connecting hole on the lower pad and the second connecting hole on the upper pressure plate.

7. The airtightness testing device for a flow battery stack according to claim 6, characterized in that, The gripping shafts are provided in four parts, which are arranged symmetrically after passing through the lower pad and the upper pressure plate in sequence.

8. The airtightness testing device for a flow battery stack according to claim 7, characterized in that, The shaft is placed through the first connecting hole on the lower pad and the second connecting hole on the upper pressure plate.

9. The airtightness testing device for a flow battery stack according to claim 4, characterized in that, The height of the shaft is greater than the overall thickness of the pad assembly, the fuel cell unit, and the pressure plate assembly.

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