A square case lithium battery restraint force uniform test fixture

Abstract

The utility model relates to the technical field of lithium battery testing equipment, concretely relates to a square shell lithium battery restraint force even test fixture, including metal clamp, two pieces of metal clamp, the square shell lithium battery is placed between two pieces of metal clamp, and the screw in four corners is connected between two pieces of metal clamp, air bag, the air bag is placed between a piece of metal clamp and square shell lithium battery, the inflation equipment, the inflation pipeline is connected air bag, inflation equipment and pressure monitoring device respectively, and pressure monitoring device is located between inflation equipment and air bag, the branch on inflation pipeline corresponding inflation equipment and pressure monitoring device all is equipped with the switch valve, is used for controlling the opening and closing of branch, the utility model provides a square shell lithium battery restraint force even test fixture that structure is simple, stress is even, restraint force is controllable and convenient operation.

Description

Technical Field

[0001] This utility model relates to the technical field of lithium battery testing equipment, specifically to a test fixture for providing uniform restraint force for prismatic lithium batteries. Background Technology

[0002] In the testing of prismatic battery cells for power batteries, energy storage batteries, and other fields, specific restraint forces need to be applied to the cells using clamps to simulate the stress state during actual operation. Existing technologies commonly employ two or three metal (steel / aluminum) clamps, with the restraint force controlled by adjusting the screws at the four corners of the clamps. Three-piece metal clamps are often used in conjunction with pressure sensors to monitor force changes during cell expansion.

[0003] However, existing fixtures have the following significant drawbacks: Uneven force distribution: The clamping surface (maximum area surface) of the square-shell battery cell has a certain degree of unevenness, and the adjustment dimensions of the four corner screws of the clamp are difficult to be completely consistent, resulting in a large deviation in the restraint force on different parts of the battery cell, which can easily lead to local excessive or insufficient force. Low accuracy of initial restraint force control: The two metal clamps cannot directly obtain the actual initial restraint force value, and the screw adjustment relies on the operator's experience, resulting in poor consistency of test results between different test batches or different operators; Complex operation: In order to reduce the force deviation, the four corner screws need to be adjusted repeatedly, which is cumbersome and time-consuming. The reliability of test results is affected: uneven stress can lead to differences in the degree of lithium plating at different locations of the cell and inconsistent utilization of active materials, which in turn affects the accuracy of life test, capacity decay and other results. Utility Model Content

[0004] In view of this, the purpose of this utility model is to propose a test fixture for prismatic lithium batteries with uniform restraint force, which overcomes the defects of existing metal fixtures in the testing of prismatic cells, such as uneven force distribution, low initial restraint force control accuracy, complicated operation and poor reliability of test results. It provides a test fixture for prismatic lithium batteries with uniform restraint force that is simple in structure, uniform in force distribution, controllable restraint force and convenient in operation.

[0005] To achieve the above objectives, this utility model provides a test fixture for uniform restraint force of prismatic lithium batteries, comprising: The metal clamp consists of two pieces, with a square-shell lithium battery inserted between the two pieces. The two metal clamps are connected by screws located at the four corners. An airbag, which is placed between a metal clamp and a square-shell lithium battery; An inflation pipe, which is connected to an airbag, an inflation device and a pressure monitoring device, with the pressure monitoring device located between the inflation device and the airbag; Each branch of the inflation pipeline corresponding to the inflation equipment and pressure monitoring device is equipped with a switch valve to control the opening and closing of the branch.

[0006] Preferably, the square-shell lithium battery has a clamping surface, which is the surface with the largest area of ​​the square-shell lithium battery. There are two clamping surfaces, which are parallel to each other and are opposite to each other. The airbag is positioned between one clamping surface of the square-shell lithium battery and a metal clamp, and the other clamping surface of the square-shell lithium battery is in contact with another metal clamp.

[0007] Preferably, the airbag size covers the clamping surface of the square lithium battery, ensuring complete coverage of the clamping surface and close contact with the square lithium battery.

[0008] Preferably, the inflation device is a precision air compressor or a nitrogen cylinder.

[0009] Preferably, the pressure monitoring device is a digital pressure gauge.

[0010] Preferably, the airbag is made of polyurethane or nitrile rubber with a thickness of 0.5-1mm.

[0011] Preferably, the area of ​​the airbag is 5%-10% larger than the area of ​​the clamping surface of the prismatic lithium battery.

[0012] Preferably, the switching valve is a manual ball valve, a solenoid valve, or a proportional valve.

[0013] The beneficial effects of this utility model are: 1. The pressure inside the airbag is equal everywhere. It can be fully fitted to the uneven clamping surface of the battery cell through flexible deformation, ensuring that the pressure (restraint force) on all parts of the battery cell is consistent. This effectively avoids the local force deviation caused by the difference in screw adjustment in traditional clamps, and significantly improves the uniformity of force.

[0014] 2. The required pressure can be accurately calculated using the formula "expected restraint force F = airbag pressure P × cell clamping surface area S". Combined with real-time feedback from the pressure monitoring device, the initial restraint force control error can be reduced to within ±1%, solving the problem that traditional two-piece clamps cannot quantify the initial restraint force.

[0015] 3. Simple and efficient operation: There is no need to repeatedly adjust the four corner screws. You only need to adjust the airbag pressure through the inflation device, which greatly reduces the difficulty of operation and reduces the test error caused by human operation differences.

[0016] 4. The pressure monitoring function can be flexibly selected to be enabled or disabled via the switch valve (it is enabled when the test needs to record the change of restraint force, and disabled when the initial restraint force is fixed), adapting to different test requirements; at the same time, the airbag material and inflation equipment parameters can be flexibly adjusted according to the cell size (clamping surface area) and the required restraint force range (1000N-30000N). Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a side view of the present invention; Figure 3 for Figure 2 A sectional view along the AA direction; Figure 4 This is a three-dimensional exploded structural diagram of the present invention.

[0019] The numbers on the map are: 1-Metal clamp; 11-Screw; 2-Airbag; 21-Inflation interface; 3-Square lithium battery. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments.

[0021] It should be noted that, unless otherwise defined, the technical or scientific terms used in this utility model should have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0022] This utility model proposes a test fixture for square-shell lithium batteries with uniform restraint force, such as... Figures 1 to 4 As shown, it includes a metal clamp 1, an airbag 2, an inflation device, a pressure monitoring device, and an inflation pipe; wherein: Metal clamp 1 consists of two pieces, made of high-strength steel or aluminum alloy (preferably No. 45 steel, 3-5mm thick, to ensure rigidity and avoid deformation). The two metal clamp pieces 1 are arranged in parallel opposite directions, and screw holes are opened at all four corners. The connection and initial fixation are achieved by stainless steel screws 11 (preferably M8 type, with anti-loosening washers) at the four corners. The square-shell lithium battery 3 is placed between two metal clamps 1, and its two parallel and opposite clamping surfaces (the surfaces with the largest area) are in contact with the clamps or airbags 2 respectively.

[0023] The airbag 2 is made of a high-pressure resistant, flexible and excellent sealing material (preferably polyurethane or nitrile rubber, 0.5-1mm thick). Its size matches the clamping surface of the square lithium battery 3 (the area is 5%-10% larger than the clamping surface of the square lithium battery 3), ensuring complete coverage and tight fit of the clamping surface of the square lithium battery 3. The airbag 2 is positioned between one of the clamping surfaces of the square lithium battery 3 and the corresponding metal clamp 1, while the metal clamp 1 on the other side is in direct contact with the other clamping surface of the square lithium battery 3.

[0024] The inflation device uses an adjustable output pressure air source device (such as a precision air compressor or nitrogen cylinder, equipped with a pressure reducing valve, with an output pressure range of 0-500 kPa) to inflate the airbag 2 with gas to regulate the pressure.

[0025] The pressure monitoring device uses a digital pressure gauge (measuring range 0-500kPa, accuracy ±0.1kPa), which is connected in series in the inflation pipe and located between the inflation device and the airbag 2, to monitor and display the pressure inside the airbag 2 in real time.

[0026] The inflation pipeline uses a pressure-resistant flexible hose (such as a PU tube with an inner diameter of 6-10mm) to connect to the inflation interface 21 of the airbag 2, the air outlet of the inflation device, and the interface of the pressure monitoring device. Switch valves are provided on the pipeline corresponding to the branches of the inflation device and the airbag 2, and the branches of the pressure monitoring device and the airbag 2, to control the opening or closing of the corresponding branches.

[0027] The on / off valve can be selected from manual ball valves, solenoid valves or proportional valves according to the requirements.

[0028] Component assembly: Place two metal clamps 1 parallel to each other, and initially connect them at the four corners with M8 stainless steel screws 11 (do not tighten the screws 11 yet, leave enough gap); place the square lithium battery 3 between the two clamps, with one clamping surface facing one clamp and the other clamping surface facing the other clamp; place the airbag 2 between the square lithium battery 3 and one of the clamps, ensuring that the airbag 2 completely covers the clamping surface of the square lithium battery 3 and that its edge does not exceed the clamp range; connect the inflation pipe to the inflation port 21 of the airbag 2, the inflation equipment, and the pressure monitoring device through the quick-connect fitting, ensuring that the pipe is sealed and leak-free; close the switch valves of the inflation equipment branch and the pressure monitoring device branch.

[0029] Restraint force adjustment and testing procedure: Parameter calculation: Determine the expected restraint force F (e.g., 5000N) according to the test requirements, measure the clamping surface area S of the square lithium battery 3 (e.g., 0.01m²), and calculate the required airbag 2 pressure P=F / S=5000N / 0.01m²=500000Pa (i.e. 500kPa).

[0030] Inflation adjustment: Open the switch valve of the inflation equipment branch and the switch valve of the pressure monitoring device branch, start the inflation equipment, and slowly inflate the airbag 2; observe the pressure change in real time through the pressure monitoring device, and when the displayed value reaches the calculated value of 500kPa, close the switch valve of the inflation equipment branch and stop inflation.

[0031] Fixture: Tighten the screws 11 at the four corners of the two metal clamps 1 to a moderate degree (so that the clamps slightly fit the airbag 2 and the square lithium battery 3 without changing the pressure of the airbag 2) to ensure that the square lithium battery 3 and the airbag 2 do not shift during the test.

[0032] Test monitoring: If the test requires recording the change of restraint force (such as monitoring the expansion force during the 3-cycle process of a prismatic lithium battery), keep the switch valve of the pressure monitoring device branch open, and the device records the pressure data in real time (converted to restraint force by F=P×S); if only the initial restraint force needs to be fixed (such as static performance testing), close the switch valve of the pressure monitoring device branch to reduce external interference.

[0033] Parameter requirements: The product of the maximum pressure that the airbag 2 can withstand and the clamping surface area of ​​the prismatic lithium battery 3 must not be less than the maximum pressure value that the prismatic lithium battery 3 may generate during the test (usually 1000N-30000N). For example, for a prismatic lithium battery 3 with a clamping surface area of ​​0.02m², the maximum pressure that the airbag 2 can withstand must not be less than 1,500,000Pa (i.e., 1500kPa) to avoid damage to the airbag 2 during the test. At the same time, the operating temperature range of the airbag 2 must cover the test environment (-20℃ to 80℃) to ensure stable performance during high and low temperature tests.

[0034] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples; within the framework of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in the details for the sake of brevity.

[0035] This utility model is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A square case lithium battery restraining force uniformity test fixture, characterized in that, include: The metal clamp consists of two pieces, with a square-shell lithium battery inserted between the two pieces. The two metal clamps are connected by screws located at the four corners. An airbag, which is placed between a metal clamp and a square-shell lithium battery; An inflation pipe, which is connected to an airbag, an inflation device and a pressure monitoring device, with the pressure monitoring device located between the inflation device and the airbag; Each branch of the inflation pipeline corresponding to the inflation equipment and pressure monitoring device is equipped with a switch valve to control the opening and closing of the branch.

2. The test fixture of claim 1, wherein the fixture is configured to apply a uniform restraining force to the battery. The square lithium battery has a clamping surface, which is the surface with the largest area of ​​the square lithium battery. There are two clamping surfaces, which are parallel to each other and opposite to each other. The airbag is positioned between one clamping surface of the square-shell lithium battery and a metal clamp, and the other clamping surface of the square-shell lithium battery is in contact with another metal clamp.

3. The test fixture of claim 2, wherein the fixture comprises a plurality of clamps, each clamp comprising a first clamp member and a second clamp member, the first clamp member and the second clamp member being configured to clamp a side of the battery between the first clamp member and the second clamp member. The airbag is sized to cover the clamping surface of the square lithium battery, ensuring complete coverage and close contact with the square lithium battery.

4. The test fixture of claim 1, wherein the fixture is a square can lithium battery fixture. The inflation device is a precision air compressor or a nitrogen cylinder.

5. The test fixture of claim 1, wherein the fixture is a square can lithium battery fixture. The pressure monitoring device is a digital pressure gauge.

6. The test fixture of claim 1, wherein the fixture is a square can lithium battery fixture. The airbag is made of polyurethane or nitrile rubber with a thickness of 0.5-1mm.

7. A test fixture for uniform restraint force of a prismatic lithium battery according to claim 1, characterized in that, The area of ​​the airbag is 5%-10% larger than the area of ​​the clamping surface of the prismatic lithium battery.

8. The test fixture of claim 1, wherein the fixture is a square can lithium battery fixture. The switching valve is a manual ball valve, a solenoid valve, or a proportional valve.

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