IV-type hydrogen storage cylinder pressure testing device and pressure testing method

Abstract

The invention discloses a pressure testing device and a pressure testing method for an IV-type hydrogen storage cylinder, and belongs to the technical field of new energy. The method comprises the following steps: S101, degassing: degassing a liquid medium until the gas content is less than M; s102, air tightness detection: installing a detection tool on a bottle opening of the hydrogen storage bottle; compressed gas is introduced from the gas injection port; when the air pressure in the hydrogen storage cylinder is P1, injection of the compressed gas is stopped, and the pressure drop rate is obtained within the time T1; if the voltage drop rate is smaller than V, the step S103 is carried out; s103, a liquid medium is injected, vacuumizing is conducted through a vacuum opening, and after pressure relief is completed, the degassed liquid medium is introduced through a liquid injection opening; when the liquid level reaches the low level of the liquid level window, vacuumizing is stopped; liquid injection is stopped when the liquid level reaches the high level of the liquid level window; s104, whether the liquid level is reduced or not is observed within the time T2, and if the liquid level is not reduced, the step S104 is executed; and S104, pressure resistance test: pressurizing to test pressure from the liquid injection port, and carrying out the pressure resistance test.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology, and in particular relates to a pressure testing device and a pressure testing method for a type IV hydrogen storage cylinder. Background Art

[0002] High-pressure gaseous hydrogen storage is currently the most mature hydrogen storage technology with a wide range of applications. Most hydrogen-powered vehicles utilize this technology for charging, discharging, and storing hydrogen. The large-capacity, high-pressure hydrogen storage bottles currently available on the market are mostly Type III and Type IV, with storage pressures of 35 MPa and 70 MPa, respectively. The higher the operating pressure of a hydrogen storage bottle, the more hydrogen it can store within the same volume.

[0003] Among the many hydrogen storage containers, Type IV hydrogen storage cylinders demonstrate significant technical advantages due to their all-composite material structure (polymer liner + carbon fiber winding layer): their mass hydrogen storage density can reach more than 5.0wt%, which is 30%-50% lighter than metal liner cylinders, and they have excellent resistance to hydrogen embrittlement and fatigue resistance, making them the preferred solution for on-board hydrogen storage systems.

[0004] However, the heterogeneous interface characteristics of the composite materials of Type IV hydrogen storage cylinders (bonding strength between the resin matrix and the fiber, and interlaminar stress distribution) complicate their failure mechanisms under high-pressure cyclic loading. To ensure their service safety, standards such as ISO 11119-3, GB / T 35544, and GB-T42612 include hydraulic burst testing as a mandatory verification method. Overpressure testing (≥2.25 times the operating pressure) is required to accurately determine the minimum burst pressure and failure mode. This test not only verifies the rationality of the cylinder's structural design but also serves as a key criterion for evaluating the consistency of the production process (e.g., fiber layup angle and curing degree). The fluctuation range of the burst pressure directly reflects product reliability, while the randomness of the failure location reveals potential manufacturing defects.

[0005] The traditional hydraulic testing method currently used in the industry faces two major technical bottlenecks: First, dissolved gas in the test medium (water) can cause air to precipitate and become trapped within the bottle during the pressurization process due to increased pressure and temperature, forming localized air cavities. This distorts the stress distribution and causes the burst location to deviate from the theoretical weak zone (usually the head transition section), affecting the determination of the true failure mode. Second, the gas compression effect causes nonlinear shifts in the pressure-volume curve, resulting in large fluctuations in burst pressure measurements, seriously affecting the evaluation of batch consistency. Furthermore, the rapid release of residual gas at the moment of failure can increase the risk of fragmentation, posing a threat to testing safety.

[0006] Therefore, it is urgent to develop a high-precision water pressure burst test method for the characteristics of type 4 hydrogen storage cylinders to eliminate the influence of gas interference on the test results and provide technical support for the high-quality development of hydrogen energy equipment. Summary of the Invention

[0007] To address the above issues, embodiments of the present invention provide a pressure testing device and method for Type IV hydrogen storage cylinders, addressing the current issues with Type IV hydrogen storage cylinders experiencing a burst position deviation from the theoretical weak zone and large fluctuations in burst pressure measurements during hydraulic pressure testing. The technical solution is as follows: In one aspect, an embodiment of the present invention provides a method for pressure testing a Type IV hydrogen storage cylinder, the method comprising: S101 Degassing: Degas the liquid medium until the gas content is less than M, where M is 0.3-0.6% of the saturated solubility of the gas.

[0008] S102 Air tightness test: Place the hydrogen storage cylinder vertically upward, install a testing tool on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder; introduce compressed gas from the gas injection port 5 on the testing tool, and close the liquid injection port 6 and vacuum port 7 on the testing tool; stop injecting compressed gas when the air pressure in the hydrogen storage cylinder is P1, and obtain the pressure drop rate within time T1; if the pressure drop rate is less than V, the air tightness is good, and then proceed to step S103; the P1 is 1.3-1.8MPa, the T1 is 2-10 minutes, and the V is 0.04-0.06MPa / min.

[0009] S103: Inject the liquid medium: first, evacuate the vacuum port 7 to relieve the pressure. After the pressure relief is completed, introduce the degassed liquid medium through the liquid injection port 6. When the liquid level reaches the lower position of the liquid level window 8, stop evacuating the vacuum port 7 and close the vacuum port 7. Reduce the injection speed until the liquid level reaches the upper position of the liquid level window 8 and stop the injection. Observe whether the liquid level decreases within the time T2. If not, execute step S104. The T2 is 2-10 minutes.

[0010] S104 Pressure test: pressurize the liquid from the injection port 6 to the test pressure at the test pressurization rate and perform the pressure test.

[0011] The liquid level window 8 is provided on the gas injection port 5, the liquid injection port 6 or the vacuum port 7, which is located above the detection tooling and has a scale thereon.

[0012] The liquid medium in the embodiment of the present invention is selected from water or hydraulic oil, and the compressed gas is selected from air, oxygen, nitrogen, carbon dioxide or inert gas.

[0013] The degassing treatment in the embodiment of the present invention includes one or more of ultrasonic degassing, vacuum degassing, inert gas degassing and high-temperature degassing.

[0014] Preferably, the degassing process in the embodiment of the present invention is a combination of ultrasonic degassing and vacuum degassing.

[0015] Specifically, in step S101, M is 0.5% of the saturated solubility of the gas; in step S102, P1 is 1.5 MPa, T1 is 5 minutes, and V is 0.05 MPa / min; in step S103, T2 is 5 minutes; in step S104, the test pressure is 2.25 times the working pressure.

[0016] Preferably, the pressure testing method for a Type IV hydrogen storage cylinder provided by an embodiment of the present invention comprises: S101 Degassing: Degas the liquid medium until the gas content is less than 0.5% of the gas saturation solubility.

[0017] S102 Air tightness test: Place the hydrogen storage cylinder vertically upward, install a testing tool on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder; introduce compressed gas from the gas injection port 5 on the testing tool, and close the liquid injection port 6 and vacuum port 7 on the testing tool; stop injecting compressed gas when the air pressure in the hydrogen storage cylinder reaches 1.5MPa, and obtain the pressure drop rate within 5 minutes; if the pressure drop rate is less than 0.05MPa / min, the air tightness is good, and proceed to step S103.

[0018] S103: Inject the liquid medium: first, evacuate the liquid through the vacuum port 7 to relieve the pressure. After the pressure relief is completed, introduce the degassed liquid medium through the liquid injection port 6. When the liquid level reaches the lower position of the liquid level window 8, stop evacuating the liquid and close the vacuum port 7. Reduce the injection speed until the liquid level reaches the upper position of the liquid level window 8. Stop the injection. Observe whether the liquid level decreases within 5 minutes. If not, execute step S104.

[0019] S104 Pressure test: pressurize the liquid from the injection port 6 to the test pressure at the test pressurization rate and perform the pressure test.

[0020] On the other hand, an embodiment of the present invention further provides a V-shaped hydrogen storage cylinder pressure testing device, comprising: The degassing structure is used to degas the liquid medium.

[0021] The detection tooling is used to be installed on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder, and is provided with a liquid injection port 6, a gas injection port 5 and a vacuum port 7; the upper ends of the liquid injection port 6, the gas injection port 5 and the vacuum port 7 pass through the detection tooling, and the upper part of the vacuum port 7 is provided with a liquid level window 8.

[0022] The compressed air supply structure is used to supply compressed gas to the gas injection port 5 and detect the pressure.

[0023] The liquid medium supply structure is used to supply the degassed liquid medium to the liquid injection port 6 and detect the pressure.

[0024] The vacuum pumping structure is used to perform vacuum pumping through the vacuum port 7.

[0025] Time record structure, used to record time.

[0026] Among them, the detection tooling in the embodiment of the present invention includes a detection tooling body 1, a convex ring coaxially arranged on the upper part of the detection tooling body 1, a connecting part 3 at the lower part of the detection tooling body 2 and a sealing structure on the detection tooling body 1, the detection tooling body 1 cooperates with the bottle mouth, the connecting part 3 is connected to the bottle mouth, and the sealing structure seals the detection tooling body 1 and the bottle mouth; the air injection port 5, the liquid injection port 6 and the vacuum port 7 are hard tubes fixed on the detection tooling body 1 and are respectively connected to the compressed air supply structure, the liquid medium supply structure and the vacuum structure through pipelines with valves, and the hard tubes are arranged vertically.

[0027] Among them, the connecting part 3 in the embodiment of the present invention is a thread that cooperates with the bottle mouth, and the sealing structure includes a lower sealing ring 4 and an upper sealing ring 2. The lower sealing ring 4 and the upper sealing ring 2 are both coaxially arranged on the detection tooling body 1 and are respectively located above and below the connecting part 3. The outer diameter of the lower sealing ring 4 is tightly matched with the inner diameter of the bottle mouth, and the outer diameter of the upper sealing ring 2 is larger than the inner diameter of the bottle mouth and it rests on the top of the bottle mouth.

[0028] Specifically, the liquid level window 8 in the embodiment of the present invention is arranged vertically, which is located above the detection tool body 1, and is provided with a scale, and its length is 2-4 cm; the lower end of the liquid filling port 6 is to the lower part of the hydrogen storage cylinder, the lower end of the gas filling port 5 is to the upper part of the hydrogen storage cylinder, and the lower end of the vacuum port 7 is flush with the lower end of the detection tool body 1. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural diagram of the detection tooling; Figure 2 It is a flow chart of the pressure testing method of Type IV hydrogen storage cylinders.

[0030] In the figure: 1 detection tool body, 2 upper sealing ring, 3 connection part, 4 lower sealing ring, 5 air injection port, 6 liquid injection port, 7 vacuum port, 8 liquid level window. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0032] Example 1 See also Figure 1, Example 1 discloses a V-shaped hydrogen storage cylinder pressure testing device, comprising: A degassing structure is used to degas a liquid medium. The liquid medium is selected from water or hydraulic oil, preferably water. Specifically, the degassing structure includes one or more of ultrasonic degassing equipment, vacuum degassing equipment, inert gas degassing equipment, and high-temperature degassing equipment.

[0033] The inspection tool is used to be installed on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder. It is provided with a liquid injection port 6, a gas injection port 5, and a vacuum port 7. The upper ends of the liquid injection port 6, gas injection port 5, and vacuum port 7 pass through the inspection tool. A liquid level window 8 is provided above the vacuum port 7 and above the inspection tool.

[0034] The compressed air supply structure is used to supply compressed gas to the gas injection port 5 and monitor the pressure. The compressed gas is selected from air, oxygen, nitrogen, carbon dioxide, or an inert gas, preferably air. Specifically, the compressed air supply structure includes a storage tank, a pressure pump, piping, valves, and a pressure gauge (or pressure sensor).

[0035] The liquid medium supply structure is used to supply the degassed liquid medium to the liquid injection port 6 and detect the pressure. Specifically, the liquid medium supply structure includes a water tank, a pressure pump, pipelines, valves, and a pressure gauge (or pressure sensor).

[0036] The vacuum pumping structure is used to perform vacuum pumping through the vacuum port 7 and is a common vacuum pump.

[0037] Time record structure, used to record time.

[0038] Example 2 See also Figure 1 Example 2 provides a V-shaped hydrogen storage cylinder pressure testing device, including a degassing structure, a detection tooling, a compressed air supply structure, a liquid medium supply structure, a vacuum structure and a time recording structure. The detection tooling is detachably arranged on the bottle mouth of the hydrogen storage cylinder and is provided with a liquid injection port 6, a gas injection port 5 and a vacuum port 7. The degassing structure is connected to the liquid medium supply structure through a pipeline, and the compressed air supply structure, the liquid medium supply structure and the vacuum structure are respectively connected to the gas injection port 5, the liquid injection port 6 and the vacuum port 7 through pipelines with valves.

[0039] Preferably, the degassing structure is a combination of ultrasonic degassing equipment and vacuum degassing equipment.

[0040] The inspection tool in this embodiment of the present invention comprises an inspection tool body 1 (equivalent to the bottle cap structure), a coaxially mounted convex ring on the upper portion of the inspection tool body 1, a connecting portion 3 on the lower portion of the inspection tool body 2, and a sealing structure on the inspection tool body 1. The inspection tool body 1 is a cylindrical structure that mates with the bottle mouth. The connecting portion 3 is connected to the bottle mouth and is specifically a threaded structure that mates with the bottle mouth. The sealing structure seals the inspection tool body 1 and the bottle mouth. Specifically, the sealing structure comprises a lower sealing ring 4 and an upper sealing ring 2. The outer diameter of the upper sealing ring 2 is larger than that of the lower sealing ring 4. The lower sealing ring 4 and the upper sealing ring 2 are coaxially mounted on the inspection tool body 1, respectively located above and below the connecting portion 3. The outer diameter of the lower sealing ring 4 is a tight fit with the inner diameter of the bottle mouth, while the outer diameter of the upper sealing ring 2 is larger than that of the bottle mouth and abuts against the top of the bottle mouth. The lower sealing ring 4 and the upper sealing ring 2 cooperate to ensure a good sealing effect. Of course, other sealing structures can also be used.

[0041] Among them, the gas injection port 5, the liquid injection port 6 and the vacuum port 7 are hard tubes fixed on the detection tool body 1 and are respectively connected to the compressed air supply structure, the liquid medium supply structure and the vacuum structure through pipelines with valves, and the hard tubes are arranged vertically. Specifically, the liquid level window 8 is arranged vertically, which is located above the detection tool body 1 and is provided with a scale (such as the minimum scale is 1mm), and its length is 2-4cm. The lower end of the liquid injection port 6 is connected to the lower part of the hydrogen storage bottle. On the one hand, it reduces the contact between the liquid and the air in the bottle during the filling process and reduces the incorporation of gas; on the other hand, it can form a stable and steadily rising liquid level as soon as possible to expel the air. The lower end of the gas injection port 5 is connected to the upper part of the hydrogen storage bottle. The lower end of the vacuum port 7 is flush with the lower end of the detection tool body 1 to facilitate exhaust.

[0042] Example 3 See also Figure 1-2 Example 3 provides a method for testing the pressure of a type IV hydrogen storage cylinder, using the pressure testing device for a type V hydrogen storage cylinder provided in Example 1 or 2, the method comprising: S101 Degassing: Degas the liquid medium until the gas content is less than M.

[0043] The liquid medium is selected from water or hydraulic oil, and is preferably water.

[0044] Wherein, M is 0.3-0.6% of the saturated solubility of the gas (an empirical value obtained through a large number of tests, which has been verified to ensure the accuracy of the test within this range).

[0045] The degassing treatment includes one or more of ultrasonic degassing, vacuum degassing, inert gas degassing and high-temperature degassing. Preferably, the degassing treatment is a combination of ultrasonic degassing and vacuum degassing.

[0046] S102 Air tightness test: Place the hydrogen storage cylinder vertically upward, and install a test fixture on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder. Inject compressed gas through the gas injection port 5 on the test fixture (open the corresponding valve), and seal the liquid injection port 6 (close the corresponding valve) and vacuum port 7 (close the corresponding valve) on the test fixture. Stop injecting compressed gas (close the corresponding valve) when the air pressure in the hydrogen storage cylinder reaches P1, and obtain the pressure drop rate within time T1. If the pressure drop rate is less than V, the air tightness is good, and step S103 is carried out; if the pressure drop rate is greater than or equal to V, the air tightness does not meet the requirements, and subsequent steps are not carried out.

[0047] The compressed gas is selected from air, oxygen, nitrogen, carbon dioxide or inert gas, and is preferably air.

[0048] Among them, P1 is 1.3-1.8MPa (an empirical value obtained through a large number of tests, and it has been verified that airtightness can be guaranteed within this range), T1 is 2-10 minutes, and V is 0.04-0.06MPa / min.

[0049] S103: Inject the liquid medium: First, vacuum is drawn through the vacuum port 7 (with the corresponding valve open) to relieve pressure. After pressure relief is complete, the degassed liquid medium is introduced through the liquid injection port 6 (with the corresponding valve open). When the liquid level reaches the lower position of the liquid level window 8, vacuum drawing is stopped and the vacuum port 7 is sealed (with the corresponding valve closed). The liquid injection speed is reduced (this process also allows for observation of the presence of liquid in the liquid medium, such as by tipping a water-filled gas cylinder or other actions to observe the presence and movement of gas in the liquid level window 8). When the liquid level window 8 reaches the upper position, liquid injection is stopped. Observe within time T2 to see if the liquid level has decreased. If not, proceed to step S104; if so, the test is unqualified and subsequent steps are not performed.

[0050] Among them, T2 is 2-10 minutes.

[0051] S104 pressure test: Pressurize the liquid through the liquid injection port 6 at the test pressure rate (continue to introduce liquid medium) to the test pressure, and then perform the pressure test. The specific test can be carried out according to ISO 11119-3, GB / T 35544 and GB-T42612.

[0052] The liquid level window 8 is provided on the gas injection port 5, the liquid injection port 6 or the vacuum port 7, which is located above the detection tooling and has a scale thereon.

[0053] Example 4 See also Figure 1-2 , Example 4 provides a method for pressure testing a Type IV hydrogen storage cylinder, the method comprising: S101 Degassing: Degas the liquid medium until the gas content is less than 0.5% of the gas saturation solubility.

[0054] S102 Air tightness test: Place the hydrogen storage cylinder vertically upward, install a testing tool on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder; introduce compressed gas from the gas injection port 5 on the testing tool, and close the liquid injection port 6 and vacuum port 7 on the testing tool; stop injecting compressed gas when the air pressure in the hydrogen storage cylinder reaches 1.5MPa, and obtain the pressure drop rate within 5 minutes; if the pressure drop rate is less than 0.05MPa / min, the air tightness is good, and proceed to step S103.

[0055] S103: Inject the liquid medium: first, evacuate the liquid through the vacuum port 7 to relieve the pressure. After the pressure relief is completed, introduce the degassed liquid medium through the liquid injection port 6. When the liquid level reaches the lower position of the liquid level window 8, stop evacuating the liquid and close the vacuum port 7. Reduce the injection speed until the liquid level reaches the upper position of the liquid level window 8. Stop the injection. Observe whether the liquid level decreases within 5 minutes. If not, execute step S104.

[0056] S104 Pressure test: pressurize the liquid from the injection port 6 to the test pressure (e.g., 2.25 times the working pressure, e.g., 157 MPa) at the test pressurization rate and perform the pressure test.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Type IV hydrogen storage cylinder pressure testing method, characterized in that: The method comprises: S101 Degassing: Degas the liquid medium until the gas content is less than M, where M is 0.3-0.6% of the saturated solubility of the gas; S102 Air tightness test: Place the hydrogen storage cylinder vertically upward, install a test tool on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder; introduce compressed gas through the gas injection port (5) on the test tool, and seal the liquid injection port (6) and vacuum port (7) on the test tool; stop injecting compressed gas when the gas pressure in the hydrogen storage cylinder reaches P1, and obtain the pressure drop rate within time T1; if the pressure drop rate is less than V, the air tightness is good, and then proceed to step S103; the P1 is 1.3-1.8MPa, the T1 is 2-10 minutes, and the V is 0.04-0.06MPa / min; S103: Injecting liquid medium: first, vacuum is drawn through the vacuum port (7) to relieve pressure. After the pressure relief is completed, the degassed liquid medium is introduced through the liquid injection port (6); when the liquid level reaches the lower position of the liquid level window (8), vacuum is stopped and the vacuum port (7) is closed; the liquid injection speed is reduced until the liquid level reaches the upper position of the liquid level window (8); the liquid injection is stopped; within a time T2, whether the liquid level decreases is observed. If not, step S104 is executed; the T2 is 2-10 minutes; S104 pressure test: pressurize the liquid injection port (6) to the test pressure at the test pressurization rate to perform the pressure test; The liquid level window (8) is provided on the gas injection port (5), the liquid injection port (6) or the vacuum port (7), and is located above the detection tooling, with a scale provided thereon.

2. The pressure testing method for type IV hydrogen storage cylinders according to claim 1, characterized in that: The liquid medium is selected from water or hydraulic oil, and the compressed gas is selected from air, oxygen, nitrogen, carbon dioxide or inert gas.

3. The pressure testing method for type IV hydrogen storage cylinders according to claim 1, characterized in that: The degassing treatment includes one or more of ultrasonic degassing, vacuum degassing, inert gas degassing and high temperature degassing.

4. The pressure testing method for type IV hydrogen storage cylinders according to claim 1, characterized in that: The degassing treatment is a combination of ultrasonic degassing and vacuum degassing.

5. The pressure testing method for type IV hydrogen storage cylinders according to claim 1, characterized in that: In step S101, M is 0.5% of the saturated solubility of the gas; in step S102, P1 is 1.5 MPa, T1 is 5 minutes, and V is 0.05 MPa / min; in step S103, T2 is 5 minutes; in step S104, the test pressure is 2.25 times the working pressure.

6. The pressure testing method for a Type IV hydrogen storage cylinder according to claim 2, characterized in that: The method comprises: S101 Degassing: Degas the liquid medium until the gas content is less than 0.5% of the gas saturation solubility; S102 Air tightness test: Place the hydrogen storage cylinder vertically upward, install a test tool on the bottle mouth of the hydrogen storage cylinder to seal the hydrogen storage cylinder; introduce compressed gas through the gas injection port (5) on the test tool, and seal the liquid injection port (6) and vacuum port (7) on the test tool; stop injecting compressed gas when the pressure in the hydrogen storage cylinder reaches 1.5MPa, and obtain the pressure drop rate within 5 minutes; if the pressure drop rate is less than 0.05MPa / min, the air tightness is good, and then proceed to step S103; S103: Injecting liquid medium: first, vacuum is drawn through the vacuum port (7) to relieve pressure. After the pressure relief is completed, the degassed liquid medium is introduced through the liquid injection port (6); when the liquid level reaches the lower position of the liquid level window (8), the vacuum is stopped and the vacuum port (7) is closed; the liquid injection speed is reduced until the liquid level reaches the upper position of the liquid level window (8); the liquid injection is stopped; within 5 minutes, the liquid level is observed to see whether it decreases. If it does not decrease, step S104 is executed; S104 Pressure resistance test: pressurize the liquid from the injection port (6) to the test pressure at the test pressurization rate to perform the pressure resistance test.

7. Type IV hydrogen storage cylinder pressure testing device, characterized in that: include: Degassing structure, used for degassing liquid medium; The detection tool is used to be installed on the bottle mouth of the hydrogen storage bottle to seal the hydrogen storage bottle, and is provided with a liquid injection port (6), a gas injection port (5) and a vacuum port (7); the upper ends of the liquid injection port (6), the gas injection port (5) and the vacuum port (7) pass through the detection tool, and the upper part of the vacuum port (7) is provided with a liquid level window (8); A compressed air supply structure for supplying compressed air to the air injection port (5) and detecting the pressure; A liquid medium supply structure is used to supply the degassed liquid medium to the liquid injection port (6) and detect the pressure; A vacuuming structure for performing vacuuming through a vacuum port (7); Time record structure, used to record time.

8. The Type IV hydrogen storage cylinder pressure testing device according to claim 7, characterized in that: The detection tooling comprises a detection tooling body (1), a convex ring coaxially arranged on the upper part of the detection tooling body (1), a connecting portion (3) at the lower part of the detection tooling body (2), and a sealing structure on the detection tooling body (1); the detection tooling body (1) cooperates with the bottle mouth, the connecting portion (3) is connected to the bottle mouth, and the sealing structure seals the detection tooling body (1) and the bottle mouth; the air injection port (5), the liquid injection port (6), and the vacuum port (7) are hard pipes fixed on the detection tooling body (1) and are respectively connected to the compressed air supply structure, the liquid medium supply structure, and the vacuum pumping structure through pipelines with valves, and the hard pipes are arranged vertically.

9. The type IV hydrogen storage cylinder pressure testing device according to claim 7, characterized in that: The connecting portion (3) is a thread that matches the bottle mouth. The sealing structure includes a lower sealing ring (4) and an upper sealing ring (2). The lower sealing ring (4) and the upper sealing ring (2) are both coaxially arranged on the detection tool body (1) and are respectively located above and below the connecting portion (3). The outer diameter of the lower sealing ring (4) is tightly matched with the inner diameter of the bottle mouth. The outer diameter of the upper sealing ring (2) is larger than the inner diameter of the bottle mouth and is pressed against the top of the bottle mouth.

10. The type IV hydrogen storage cylinder pressure testing device according to claim 7, characterized in that: The liquid level window (8) is vertically arranged and located above the detection tool body (1). A scale is provided on the liquid level window, and the length thereof is 2-4 cm. The lower end of the liquid injection port (6) is connected to the lower part of the hydrogen storage cylinder, the lower end of the gas injection port (5) is connected to the upper part of the hydrogen storage cylinder, and the lower end of the vacuum port (7) is flush with the lower end of the detection tool body (1).

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