A method and system for detecting compression boundaries of a fuel cell bipolar plate seal

Abstract

The application provides a kind of fuel cell bipolar plate seal compression boundary detection method and system, it is related to fuel cell technical field, comprising: obtaining the compression displacement of different bipolar plate seal under different compression rate;Get the relationship between the compression rate and the compression displacement of seal;The compression rate is divided into preset grade, and the bipolar plate is pressed according to different preset grade;Obtain the leakage of bipolar plate under different compression grade, get the relationship between the leakage and the compression rate or the compression displacement of seal;When the leakage is within the preset leakage threshold range, the compression boundary of bipolar plate seal is determined according to the corresponding compression displacement under the compression rate.The application is rigorous and efficient, on the one hand, it can efficiently realize the acquisition of single bipolar plate seal compression boundary, on the other hand, it can accumulate database, not only can be applied to "two-plate three-cavity type" bipolar plate design, but also suitable for "single cell type" sealing design, realize equipment multi-use, reduce test cost.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell testing technology, and particularly relates to a method and system for detecting the compression boundary of a fuel cell bipolar plate seal. Background Technology

[0002] A hydrogen fuel cell is an energy conversion device that directly converts chemical energy into electrical energy. Due to its advantages such as zero pollution, low noise, and high efficiency, it is widely used in transportation, stationary power generation, aerospace, marine propulsion, and many other fields. Good sealing performance is a key guarantee for the usability of a hydrogen fuel cell stack. As an important part of the sealing design phase, properly determining the compression displacement and compressibility boundaries of the sealing components directly affects the sealing performance.

[0003] The related technology provides a fuel cell bipolar plate air tightness testing device and testing method. The testing process involves applying force to the fixture through a force-applying component, introducing gas at a certain pressure, detecting the leakage amount, comparing the leakage amount with the requirements, and determining whether the sealing performance meets the requirements.

[0004] However, applying different pressures can change the compression displacement of the seal, and the compression ratio of the seal will change with different pressures. The sealing performance of the seal is different under different compression ratios, so it is not possible to intuitively determine whether the sealing performance meets the requirements. Summary of the Invention

[0005] This invention provides a method and system for detecting the compression boundary of a fuel cell bipolar plate seal. By automatically lifting and lowering the device, air tightness testing is achieved under different seal compression ratios and compression displacements, thereby obtaining the seal compression boundary for seal structure design. This method is rigorous and efficient, and can also perform air tightness testing. The equipment is multi-functional, reducing testing and inspection costs.

[0006] The technical solution provided by this invention is as follows:

[0007] On the one hand, a method for detecting the compression boundary of a fuel cell bipolar plate seal is provided, the method comprising:

[0008] Obtain the compression displacement of different bipolar plate seals under different compression ratios;

[0009] The relationship between the compression ratio and compression displacement of the bipolar plate seal and the lifting distance of the limiting device was obtained.

[0010] The compression ratio is divided into preset levels, and pressure is applied to the bipolar plate according to different preset levels;

[0011] The leakage of bipolar plates under different compression levels was obtained, and the relationship between leakage and seal compression ratio or compression displacement was obtained.

[0012] When the leakage is within the preset leakage threshold range, the compression boundary of the bipolar plate seal is determined according to the compression displacement corresponding to the compression ratio of the seal.

[0013] In an optional embodiment, a detection device for the compression boundary of the fuel cell bipolar plate seal is also included.

[0014] The detection device includes an upper clamp, a lower clamp, and a limiting device;

[0015] The upper clamp and the lower clamp are arranged opposite to each other, and the limiting device is located inside the lower clamp;

[0016] The limiting device can adjust the compression displacement of the upper clamp and the lower clamp during detection according to the compression boundary of the bipolar plate seal.

[0017] In one optional embodiment, the limiting device includes a limiting groove, a limiting block, and a lifting mechanism;

[0018] The limiting groove is located inside the lower clamp, and the limiting block is connected to the limiting groove through the lifting mechanism;

[0019] The limiting block can be raised and lowered along the position of the lower clamp to the upper clamp via the lifting mechanism.

[0020] In one alternative embodiment, the detection device further includes an inflation chamber located on the inner surfaces of the upper and lower clamps.

[0021] In an optional embodiment, the detection device further includes a pressure generating unit for applying pressure to the detection device.

[0022] In an optional embodiment, the detection device further includes a positioning hole located on the upper clamp and the lower clamp.

[0023] In an optional embodiment, the method further includes detecting the bipolar plate using the detection device.

[0024] In one optional embodiment, the bipolar plate is tested by the detection device, including obtaining the lifting distance of the limiting device of the bipolar plate seal under different compression rates and compression displacements.

[0025] The relationship between the compression ratio, compression displacement, and lifting distance of the limiting device for each bipolar plate seal is obtained based on the compression ratio, compression displacement, and lifting distance of the limiting device for each bipolar plate seal.

[0026] The lifting distance of the limit device during the testing process is determined based on the relationship between the compression ratio, compression displacement, and lifting distance of each bipolar plate seal.

[0027] In an optional embodiment, the method further includes obtaining the maximum contact stress boundary of each bipolar plate seal based on the relationship between the compression ratio, compression displacement, and lifting distance of the limiting device for each bipolar plate seal.

[0028] On the other hand, a detection system for the compression boundary of a fuel cell bipolar plate seal is provided, the system including a computer-readable storage medium having a program on which any of the methods described above are executed.

[0029] The method provided in this embodiment of the invention has at least the following beneficial effects:

[0030] The method provided in this invention obtains the compression displacement of different bipolar plate seals at different compression rates, thus establishing the relationship between the seal compression rate and the compression displacement. Based on this relationship, bipolar plates can be divided into different compression levels for compression, yielding the leakage amount of the bipolar plate at each compression level, and the relationship between the leakage amount and the seal compression rate and compression displacement. When the leakage amount is within a preset leakage threshold range, the compression boundary of the bipolar plate seal is determined based on the corresponding compression displacement at the seal compression rate. This method is rigorous and efficient. On one hand, it efficiently obtains the compression boundary of the bipolar plate seal; on the other hand, it accumulates a database. It can be applied not only to "two-plate, three-chamber" bipolar plate designs but also to "single-cell" sealing designs, enabling multi-purpose equipment and reducing testing costs. Attached Figure Description

[0031] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0032] Figure 1 A schematic flowchart of a method for detecting the compression boundary of a fuel cell bipolar plate seal is shown.

[0033] Figure 2 A schematic diagram of a test apparatus for the compression boundary of a fuel cell bipolar plate seal is shown.

[0034] The attached figures are labeled as follows:

[0035] 1-Upper clamp; 2-Lower clamp; 3-Positioning hole; 4-Inflation chamber; 5-Limiting device. Detailed Implementation

[0036] Embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0037] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0038] On the one hand, such as Figure 1 As shown, a method for detecting the compression boundary of a fuel cell bipolar plate seal is provided, the method comprising:

[0039] S1. Obtain the compression displacement of different bipolar plate seals under different compression rates.

[0040] S2. Obtain the relationship between the compression ratio of the seal and the compression displacement.

[0041] S3. Divide the compression ratio into preset levels and apply pressure to the bipolar plate according to different preset levels.

[0042] S4. Obtain the leakage of the bipolar plate under different compression levels, and obtain the relationship between the leakage and the compression ratio or compression displacement of the seal.

[0043] S5. When the leakage is within the preset leakage threshold range, the compression boundary of the bipolar plate seal is determined according to the compression displacement corresponding to the seal compression ratio.

[0044] The methods provided by the embodiments of the present invention will be further explained and described below through optional examples.

[0045] In an optional embodiment, a detection device for the compression boundary of the fuel cell bipolar plate seal is also included.

[0046] The detection device includes an upper clamp 1, a lower clamp 2, and a limiting device 5;

[0047] The upper clamp 1 and the lower clamp 2 are arranged opposite to each other, and the limiting device 5 is located inside the lower clamp 2;

[0048] The limiting device 5 can adjust the compression displacement of the upper clamp 1 and the lower clamp 2 during the detection according to the compression boundary of the bipolar plate seal.

[0049] Under constant pressure, by controlling the height of the limiting device 5, different compression displacements of the bipolar plate seal can be achieved, resulting in different compression ratios (theoretically, it can reach 0% to max, where max represents the compression ratio of the seal at the maximum compression displacement that the bipolar plate sealing groove can achieve), which can be used for product sealing testing.

[0050] In one optional embodiment, the limiting device 5 includes a limiting groove, a limiting block, and a lifting mechanism;

[0051] The limiting groove is located inside the lower clamp 2, and the limiting block is connected to the limiting groove through a lifting mechanism;

[0052] The limit block can be raised and lowered along the position of the lower clamp 2 to the upper clamp 1 via the lifting mechanism.

[0053] The limiting block is connected to the lifting mechanism, which includes a lifting rod and a lifting platform. The lifting platform is located within the limiting groove. The lifting rod can be controlled by a controller, meaning its lifting height can be controlled by the seal compression rate or compression displacement, thereby controlling the lifting height of the limiting block. By moving the limiting block, different compression displacements can be rapidly changed during bipolar plate airtightness testing to meet the needs of different scenarios, improving efficiency and expanding the application range.

[0054] In an optional embodiment, the detection device further includes an inflation chamber 4 located on the inner surfaces of the upper clamp 1 and the lower clamp 2.

[0055] The method provided in this invention can not only detect the compression boundary of the bipolar plate seal of a fuel cell, but also detect the airtightness of the bipolar plate, and has wide applicability.

[0056] In an optional embodiment, the detection device further includes a pressure generating unit for applying pressure to the detection device.

[0057] Furthermore, the pressure generating unit is a pressure sensor.

[0058] In an optional embodiment, the detection device further includes a positioning hole 3 located on the upper clamp 1 and the lower clamp 2.

[0059] The upper clamp 1 and the lower clamp 2 can be connected through the positioning hole 3. For example, the positioning hole 3 can be a bolt hole.

[0060] S1. Obtain the compression displacement of different bipolar plate seals under different compression rates.

[0061] It should be noted that bipolar plates are sealed using seals. When testing their airtightness, relevant technologies continuously apply pressure to the testing device, introduce gas at a certain pressure, and then measure the leakage. The leakage is then compared with the required level to determine whether the sealing performance meets the requirements. However, applying different pressures will change the compression displacement of the bipolar plate seal, causing the seal's compression ratio to change with different pressures. The sealing performance varies under different compression ratios, therefore, it is impossible to directly determine whether the sealing performance meets the requirements.

[0062] Therefore, this embodiment of the invention obtains the compression displacement of different bipolar plate seals under different compression rates and records the data to obtain the relationship between the compression rate and compression displacement of each bipolar plate seal under different compression rates.

[0063] S2. Obtain the relationship between the compression ratio of the seal, the compression displacement, and the lifting distance of the limiting device.

[0064] When conducting an airtightness test on a bipolar plate, the compression rate is continuously increased or decreased according to a preset compression rate. At this time, there will be a corresponding relationship between the compression rate, compression displacement and the lifting distance of the limiting device. The corresponding relationship includes one compression rate and compression displacement corresponding to one lifting distance, or multiple compression rates and compression displacements corresponding to more than one lifting distance.

[0065] S3. Divide the compression ratio into preset levels and apply pressure to the bipolar plate according to different preset levels.

[0066] The compression ratio is divided into preset levels according to equal or unequal intervals, and pressure is applied to the bipolar plate according to different preset compression ratio levels. Preferably, pressure can be applied in order of increasing compression ratio. Preferably, dividing the compression ratio into preset levels according to equal intervals can also distribute the compression displacement at equal intervals, making it easier to find the relationship between compression ratio and compression displacement.

[0067] S4. Obtain the leakage of the bipolar plate under different compression levels, and obtain the relationship between the seal compression ratio or compression displacement and the compression ratio.

[0068] It is understandable that when the compression ratio is applied within the leakage pressure range of the bipolar plate, the bipolar plate seal will leak. When the compression ratio is applied at the preset level, the bipolar plate seal will undergo compression displacement. When compression displacement occurs, the bipolar plate will leak. At this time, the leakage amount of the bipolar plate under different compression levels is obtained to obtain the relationship between the leakage amount and the compression ratio or compression displacement of the seal.

[0069] Furthermore, the relationship between leakage and seal compression ratio or compression displacement can be a one-to-one correspondence, or one leakage can correspond to at least two compression ratios or compression displacements.

[0070] Furthermore, initially, pressure can be applied to the bipolar plate using a compression rate of one step amplitude. If the bipolar plate does not displace under the compression force of the first step amplitude, pressure can be applied to the bipolar plate using a compression rate of the second step amplitude. Furthermore, the second step amplitude is smaller than the first step amplitude.

[0071] S5. When the leakage is within the preset leakage threshold range, the compression boundary of the bipolar plate seal is determined according to the compression displacement corresponding to the seal compression ratio.

[0072] In an alternative embodiment, the method further includes detecting the bipolar plate using a detection device.

[0073] In an optional embodiment, the bipolar plate is detected by a detection device, including obtaining the lifting distance of the limit device 5 under different sealing compression rates or compression displacements of different bipolar plates.

[0074] The relationship between the compression ratio, compression displacement, and lifting distance of the limiting device 5 for each bipolar plate seal is obtained based on the compression ratio, compression displacement, and lifting distance of each bipolar plate seal.

[0075] The lifting distance of the limiting device 5 during the testing process is determined based on the relationship between the compression ratio, compression displacement, and lifting distance of each bipolar plate seal.

[0076] Understandably, when testing the airtightness of a bipolar plate using a testing device, the bipolar plate is placed inside the device, and pressure is applied. When the bipolar plate undergoes compression displacement, the limiting device 5 also moves accordingly. The lifting distance of the limiting device 5 under different sealing compression rates or compression displacements for different bipolar plates is then obtained. Based on the sealing compression rate, compression displacement, and lifting distance of the limiting device 5 for each bipolar plate, the relationship between these factors is derived. This relationship includes one sealing compression rate corresponding to one compression displacement and one lifting distance of the limiting device 5, or multiple sealing compression rates corresponding to multiple compression displacements and multiple lifting distances of the limiting device 5.

[0077] Furthermore, the position of the multiple limiting devices 5 after lifting and lowering is equal to the compression displacement after subtracting the height of the limiting devices 5 in the mounting groove.

[0078] In an alternative embodiment, the method further includes obtaining the maximum contact stress boundary of each bipolar plate seal based on the relationship between the compression ratio of each bipolar plate seal, the compression displacement, and the lifting distance of the limiting device 5.

[0079] It is understood that the embodiments of the present invention provide the compression boundary of the bipolar plate seal, i.e., the compression displacement or compression ratio. Furthermore, the maximum contact stress boundary of each bipolar plate seal is obtained based on the relationship between the compression ratio, compression displacement, and lifting distance of the limiting device 5, which provides a more intuitive representation of the compression boundary of the bipolar plate seal. As an example, when the maximum compression displacement of the bipolar plate seal is 10 mm, the maximum stress it can withstand is 10 MPa.

[0080] The methods provided by the embodiments of the present invention will be further explained and described below through specific examples.

[0081] Obtain the compression displacement of the bipolar plate seal under different compression rates, determine the required limit block height, and determine the correspondence between compression displacement, compression rate, and limit block height (limit device lifting distance).

[0082] The test starts at a 30% compression rate to obtain the leakage amount, and then the leakage amount is compared with the required leakage amount.

[0083] Leakage was recorded at compression rates of 29%, 28%, etc., in increments of 1%.

[0084] When the leakage is lower than or close to the required amount, record the compression ratio, compression displacement and height of the limiting block of the seal at this time, which is the maximum compression boundary of the seal.

[0085] Furthermore, the maximum contact stress boundary of the seal can be obtained through simulation using the above data.

[0086] Furthermore, 1. First determine the required leakage rate: Test according to the flow rate method. Simultaneously introduce 200 kPa.a of air into the hydrogen chamber, air chamber and water chamber, and observe the leakage rate. The external leakage rate of the three chambers should be ≤0.8 mL / min.

[0087] 2. Calculate the relationship between the seal compression ratio, compression displacement, and the lifting height of the limiting device:

[0088] 1) Determine the original seal thickness as a in advance, where a is 0.8 mm, the compression rate is α (10% to 80%), the step size is set to 5%, and the compression displacement b is a × α, where b is between 0.08 and 0.64.

[0089] 2) Calculate the lifting height of the limit block: The original position of the limit block is parallel to the plane of the limit groove, and the lifting height is h = 2(ab), where h is between 1.44 and 0.32;

[0090] 3) Record the corresponding data of compression ratio, compression displacement and limit block rise height in a table, as shown in Table 1 below.

[0091] Table 1

[0092]

[0093]

[0094] 3. Determine the upper limit of the compression boundary for seal structural failure:

[0095] 1) Place the bipolar plate between the upper clamp 1 and the lower clamp 2 of the testing device, control the compression rate to α1 = 50%, and after a period of time (which can be 30 minutes), release the pressure and observe the microstructure of the seal to see if cracks appear.

[0096] 2) If no cracks appear, increase the seal compression ratio and repeat step 1); if cracks appear, decrease the seal compression ratio and repeat step 1.

[0097] 3) Until cracks appear in the seal, the corresponding compression ratio α2 and compression displacement c are the upper limit of the seal's compression boundary. In subsequent tests, the compression ratio of the seal will be controlled within the range of 10% to α2.

[0098] 4) The structural observation results are shown in Table 2 below. The results show that the seal will collapse when the compression ratio is α2. In subsequent tests, the compression ratio will be controlled between 10% and α2.

[0099] Table 2

[0100] 1 50 good 2 60 tiny cracks 3 70 large crack

[0101] 4. Testing process:

[0102] 1) Start testing with a 30% compression ratio to measure the leakage. If it meets the user's requirements, reduce the compression ratio in increments of 5% to determine the required compression ratio range. If it does not meet the customer's requirements, increase the compression ratio in increments of 5% to determine the required compression ratio range. The actual situation is shown in Table 3 below. The results show that at a 30% compression ratio, the measured actual leakage k1≤k, which meets the customer's requirements. Therefore, we choose to reduce the compression ratio in increments of 5%, and finally determine that the compression ratio boundary should be between α6 and α5.

[0103] Table 3

[0104] 1 30 0.65 2 25 0.71 3 20 0.73 4 15 0.75 5 10 0.82

[0105] 2) Subdivide the compression ratio and determine the compression ratio boundary: Subdivide the compression ratio range with a step size of 5% into 1% increments, test the leakage amount, and determine the boundary; see Table 4 below for actual conditions. Subdivide the compression ratio of 10%-15% and test the leakage amount separately. The results show that under the requirement of leakage amount ≤0.8, the compression ratio boundary is about 13%.

[0106] Table 4

[0107]

[0108]

[0109] Furthermore, by substituting the compression ratio and compression displacement of 13% and 0.104 mm into the simulation model, the maximum contact stress of the seal was found to be 1.2 MPa.

[0110] On the other hand, a detection system for the compression boundary of a fuel cell bipolar plate seal is provided, the system including a computer-readable storage medium having a program on the computer-readable storage medium for performing any of the above methods.

[0111] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for detecting the compression boundary of a fuel cell bipolar plate seal, characterized in that, The method includes: Obtain the compression displacement of different bipolar plate seals under different compression ratios; The relationship between the seal compression ratio and the compression displacement was obtained. The compression ratio is divided into preset levels, and pressure is applied to the bipolar plate according to different preset levels; The leakage of bipolar plates under different compression levels was obtained, and the relationship between leakage and seal compression ratio or compression displacement was obtained. When the leakage is within the preset leakage threshold range, the compression boundary of the bipolar plate seal is determined according to the compression displacement corresponding to the compression ratio of the seal.

2. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 1, characterized in that, It also includes a device for detecting the compression boundary of fuel cell bipolar plate seals. The detection device includes an upper clamp, a lower clamp, and a limiting device; The upper clamp and the lower clamp are arranged opposite to each other, and the limiting device is located inside the lower clamp; The limiting device can adjust the compression displacement of the upper clamp and the lower clamp during detection according to the compression boundary of the bipolar plate seal.

3. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 2, characterized in that, The limiting device includes a limiting groove, a limiting block, and a lifting mechanism; The limiting groove is located inside the lower clamp, and the limiting block is connected to the limiting groove through the lifting mechanism; The limiting block can be raised and lowered along the position of the lower clamp to the upper clamp via the lifting mechanism.

4. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 2, characterized in that, The detection device further includes an inflation chamber located on the inner surfaces of the upper and lower clamps.

5. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 2, characterized in that, The detection device further includes a pressure generating unit, which is used to apply pressure to the detection device.

6. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 2, characterized in that, The detection device further includes a positioning hole located on the upper clamp and the lower clamp.

7. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 2, characterized in that, The method further includes detecting the bipolar plate using the detection device.

8. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 7, characterized in that, The bipolar plate is tested by the detection device, including obtaining the lifting distance of the limiting device under different compression rates and compression displacements for different bipolar plates; The relationship between the compression ratio, compression displacement, and lifting distance of the limiting device for each bipolar plate seal is obtained based on the compression ratio, compression displacement, and lifting distance of the limiting device for each bipolar plate seal. The lifting distance of the limiting device during the testing process is determined based on the relationship between the compression ratio, compression displacement, and moving distance of each bipolar plate seal.

9. The method for detecting the compression boundary of the fuel cell bipolar plate seal according to claim 8, characterized in that, The method further includes obtaining the maximum contact stress boundary of the bipolar plate seal based on the relationship between the compression ratio, compression displacement, and lifting distance of the limiting device for each bipolar plate seal.

10. A detection system for the compression boundary of a fuel cell bipolar plate seal, characterized in that, The system includes a computer-readable storage medium having a program thereon that performs the method of any one of claims 1-9.

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