A method for determining the length of a battery module bundling strap

Abstract

The present invention relates to the technical field of battery modules, and provides a method for determining the length of a bundling strap for a battery module, which includes the following steps: calculating the theoretical geometric length of the bundling strap according to the geometric dimensions of the battery module; calculating the theoretical pre-tightening force of the bundling strap according to the pre-tightening force requirement of the battery module; conducting a tensile test on the bundling strap to obtain the linear coefficient between the deformation of the bundling strap and the tensile force; determining whether the linear coefficient is within a predetermined range, and if so, correcting the theoretical geometric length according to the product of the theoretical pre-tightening force and the linear coefficient to obtain the corrected length of the bundling strap. The present invention can overcome the deficiencies in the prior art that the length of the bundling strap is verified by actual measurement. Whenever the size of the battery module changes, it is necessary to re-conduct the test, which is cumbersome, time-consuming and laborious.

Description

Technical Field

[0001] The present invention relates to the technical field of battery modules, and particularly relates to a method for determining the length of a bundling strap for a battery module. Background Art

[0002] Existing battery modules are generally formed by stacking multiple battery cells. To ensure the integrity and stiffness of the battery module, a bundling strap is also provided around the battery module. The bundling strap can generate a pre-tightening force along the length direction of the battery module, thereby pressing the battery cells, end plates, and insulating sheets in the battery module against each other. It can be seen that the magnitude of the pre-tightening force generated by the bundling strap can directly affect the integrity and stiffness of the battery module, and there is a strong correlation between the pre-tightening force of the bundling strap and its length. Therefore, the length of the bundling strap is one of the key points in the design of the battery module.

[0003] However, the pre-tightening force that the bundling strap can generate is related not only to its length but also to many other parameters, such as the cross-sectional shape and size of the bundling strap and the material of the bundling strap. The current research on the pre-tightening force in this field is not sufficient, so there is no clear calculation method for the length of the bundling strap in the existing specifications. Those skilled in the art often adopt the method of initially determining the length of the bundling strap, testing to determine the pre-tightening force, adjusting the length of the bundling strap according to the test results, and repeating the test and adjustment until the pre-tightening force meets the requirements. However, the length of the bundling strap measured by this method can only be adapted to the battery module used in the test. Whenever the size specification of the battery module changes, it is necessary to re-conduct repeated tests and adjustments for the new battery module, which is cumbersome and time-consuming, and will slow down the entire production process of the battery module. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies that in the prior art, the method of actually measuring is used to verify whether the length of the bundling strap meets the requirements, and whenever the size of the battery module changes, it is necessary to re-conduct tests, and the steps are cumbersome and time-consuming, and to provide a method for determining the length of a bundling strap for a battery module.

[0005] In a first aspect, the present invention provides a method for determining the length of a bundling strap for a battery module, comprising the following steps:

[0006] Calculate the theoretical geometric length of the bundling strap according to the geometric dimensions of the battery module; calculate the theoretical pre-tightening force of the bundling strap according to the pre-tightening force requirement of the battery module;

[0007] Conduct a tensile test on the bundling strap to obtain the linear coefficient between the deformation of the bundling strap and the tensile force;

[0008] Judge whether the linear coefficient is within a predetermined interval. If so, correct the theoretical geometric length according to the product of the theoretical pre-tightening force and the linear coefficient to obtain the corrected length of the bundling strap.

[0009] Calculate the theoretical geometric length of the bundling strap based on the geometric dimensions of the battery module, that is, without considering the pre-tightening force, assuming the length of the bundling strap when it is closely attached to the corresponding installation area on the outer surface of the battery module at all points along its length; the calculation of the theoretical geometric length and the theoretical pre-tightening force can occur either before or after the tensile test.

[0010] The linear coefficient reflects the deformation ability of the bundling strap, and its predetermined range can be given according to test results or experience, so that the bundling strap is neither too tight to cause difficult installation and poor compatibility, nor too loose to cause insufficient rigidity of the battery module, excessive displacement of the battery module due to expansion and affect the actual life.

[0011] Correct the theoretical geometric length according to the product of the theoretical pre-tightening force and the linear coefficient. For example, directly subtract the product of the theoretical pre-tightening force and the linear coefficient from the theoretical geometric length, or give a correction coefficient according to actual experience, use the correction coefficient to amplify or reduce the product of the theoretical pre-tightening force and the linear coefficient, and then perform addition and subtraction operations with the theoretical geometric length, or directly use the correction coefficient to amplify or reduce the difference between the theoretical geometric length and the product of the theoretical pre-tightening force and the linear coefficient.

[0012] The inventors of the present invention found that for bundling straps of the same material, even if their size parameters such as length, thickness, and width change, the linear coefficient between their deformation amount and tensile force is almost unchanged; for example, for bundling straps with widths of 19mm, 23mm, and 30mm respectively, the difference in their linear coefficients is less than 0.002, which is acceptable for the length design of the bundling strap; therefore, the method for determining the length of the bundling strap of the battery module in this solution first obtains the linear coefficient through a tensile test before determining the length of the bundling strap, and then corrects the theoretical geometric length according to the product of the linear coefficient and the theoretical pre-tightening force to obtain the corrected length; since the linear coefficient reflects the relationship between the deformation amount and tensile force of the bundling strap, the product of the theoretical pre-tightening force and the linear coefficient reflects the theoretical deformation amount required for the bundling strap to generate the theoretical pre-tightening force. Using this theoretical deformation amount to correct the theoretical geometric length can ensure that the bundling strap can generate the theoretical pre-tightening force, and thus ensure that the integrity and stiffness of the battery module meet the requirements.

[0013] And as mentioned above, this linear coefficient mainly depends on the material of the bundling strap and is little affected by other factors, such as the width of the bundling strap and the size specifications of the battery module; therefore, when the size specifications of the battery module or the required pre-tightening force change, this solution uses this linear coefficient and substitutes the new battery module size or pre-tightening force to recalculate the length of the bundling strap, without the need to repeat the tensile test and adjustment like the prior art, thus saving a lot of manpower and material resources for cumbersome testing and adjustment operations and improving the production efficiency of the battery module.

[0014] Meanwhile, this solution also judges the linear coefficient through a preset interval, which can ensure that the tightness of the strapping is moderate, neither too tight to cause difficulties in installing the strapping and poor compatibility, nor too loose to cause insufficient rigidity of the battery module and displacement of the battery module beyond the design interval due to expansion, affecting the actual life.

[0015] Preferably, when judging whether the linear coefficient is within a predetermined interval, if not, change the material of the strapping, re-obtain the linear coefficient and judge whether the linear coefficient is within the predetermined interval.

[0016] This solution gives the operations required when the linear coefficient is outside the predetermined interval. Since the linear coefficient in this solution mainly depends on the material of the strapping and is little affected by other factors, such as the width of the strapping and the size specifications of the battery module, directly replacing the material of the strapping has a higher correction efficiency if the linear coefficient is outside the predetermined interval.

[0017] Preferably, the corrected length of the strapping is calculated according to the following formula:

[0018] L = L1 - KF2

[0019] In the formula, L represents the corrected length of the strapping; L1 represents the theoretical geometric length of the strapping; F2 represents the theoretical pre-tightening force of the strapping; K represents the linear coefficient of the strapping.

[0020] This solution gives the specific formula for calculating the corrected length of the strapping.

[0021] Preferably, the linear coefficient of the strapping is calculated according to the following formula:

[0022]

[0023] In the formula, K represents the linear coefficient of the strapping; ΔL represents the deformation amount when the strapping is stretched, and F represents the tensile force applied to the strapping.

[0024] This solution gives the specific formula for calculating the linear coefficient of the strapping.

[0025] Preferably, the range of the predetermined interval is that the linear coefficient is greater than or equal to 0.001 and less than or equal to 0.004.

[0026] Based on a large amount of experimental data of the inventor, this solution gives the recommended range of the predetermined interval, which can ensure that the tightness of the strapping is moderate, neither too tight to cause difficulties in installing the strapping and poor compatibility, nor too loose to cause insufficient rigidity of the battery module and displacement of the battery module beyond the design interval due to expansion, affecting the actual life.

[0027] Preferably, when conducting a tensile test on the strapping, at least two groups of strappings with different widths are selected for the tensile test.

[0028] In the actual production process, it is common to use strapping tapes with different width specifications. Therefore, this solution recommends selecting at least two groups of strapping tapes with different widths in the tensile test to ensure that the data of the tensile test can cover the actual usage situation.

[0029] Preferably, when performing a tensile test on the strapping tape, the tensile force applied to the strapping tape is less than or equal to 1000 kgf.

[0030] This solution recommends the value range of the tensile force applied to the strapping tape in the tensile experiment. This range matches the tensile force range applied to the strapping tape during the actual assembly process of the battery module, and can ensure that the data obtained from the tensile test matches the actual situation.

[0031] Preferably, calculate the theoretical pre-tightening force of the strapping tape according to the following formula:

[0032] F2 = F1 / m

[0033] In the formula, F2 represents the theoretical pre-tightening force of the strapping tape, m represents the number of strapping tapes; F1 represents the pre-tightening force required for the battery module.

[0034] This solution gives a specific formula for calculating the theoretical pre-tightening force of the strapping tape.

[0035] Preferably, calculate the theoretical geometric length of the strapping tape according to the following formula:

[0036] L1 = D1 * n + D2 * (n - 1) + (D3 + D4) * 2

[0037] In the formula, L1 represents the theoretical geometric length of the strapping tape; D1 represents the thickness of the battery cells in the battery module, D2 represents the gap between the battery cells, n represents the number of battery cells; D3 represents the thickness of the end plate in the battery module, D4 represents the thickness of the insulating sheet of the end plate.

[0038] This solution gives a specific formula for calculating the theoretical geometric length of the strapping tape.

[0039] Preferably, after obtaining the linear coefficient, use the magnification coefficient to magnify the linear coefficient and the predetermined interval; when calculating the corrected length, subtract the product of the theoretical pre-tightening force, the linear coefficient, and the reciprocal of the magnification coefficient from the theoretical geometric length; the magnification coefficient is divisible by 50.

[0040] The magnification coefficient is divisible by 50, that is, the magnification coefficient is an integer multiple of 50, such as 50, 100, 150.

[0041] In the actual production process, the preload force is often a multiple of 50, and the linear coefficient often has too many decimal places, which is inconvenient in recording and calculation. Therefore, this scheme extracts the amplification factor from the preload force and uses the amplification factor to amplify the linear coefficient to facilitate the recording and calculation of the linear coefficient; correspondingly, the predetermined interval also needs to be amplified using the linear coefficient (that is, the upper and lower limits of the predetermined interval need to be multiplied by the amplification factor), and when calculating the corrected length, the linear coefficient needs to be multiplied by the inverse of the amplification factor to remove the amplification factor.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention provides a method for determining the length of a battery module strapping strap. A linear coefficient that can reflect the linear relationship between the deformation amount and the tension of the strapping strap is obtained through a tensile test, and the theoretical geometric length is corrected using the product of the linear coefficient and the theoretical preload force, so as to ensure that the strapping strap can generate the theoretical preload force, thereby ensuring that the integrity and rigidity of the battery module meet the requirements. When the size specification or the required preload force of the battery module changes, the linear coefficient is used, and the new battery module size or preload force is substituted to recalculate the length of the strapping strap, without the need to repeat the tensile test and adjustment as in the prior art, thereby eliminating tedious testing and adjustment operations, saving a lot of manpower and material resources, and improving the production efficiency of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of a method for determining the length of a battery module strapping strap of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0046] like Figure 1 As shown, a method for determining the length of a battery module strapping belt comprises the following steps:

[0047] S1. Calculate the theoretical geometric length of the strapping tape according to the geometric dimensions of the battery module; calculate the theoretical preload force of the strapping tape according to the preload force requirement of the battery module;

[0048] S2. Perform a tensile test on the strapping belt to obtain a linear coefficient between the deformation amount and the tension of the strapping belt;

[0049] S3, determine whether the linear coefficient is within the predetermined interval, if not, change the material of the strapping tape, re-obtain the linear coefficient and determine whether the linear coefficient is within the predetermined interval, that is, repeat steps S2 to S3; if yes, jump to step S4;

[0050] S4. Modify the theoretical geometric length according to the product of the theoretical pre-tightening force and the linear coefficient to obtain the modified length of the strapping band.

[0051] In an alternative embodiment, the theoretical geometric length of the strapping band can be calculated according to the following formula in step S1:

[0052] L1 = D1 * n + D2 * (n - 1) + (D3 + D4) * 2

[0053] In the formula, L1 represents the theoretical geometric length of the strapping band; D1 represents the thickness of the battery cells in the battery module, D2 represents the gap between the battery cells, n represents the number of battery cells; D3 represents the thickness of the end plate in the battery module, and D4 represents the thickness of the insulating sheet of the end plate.

[0054] In an alternative embodiment, the theoretical pre-tightening force of the strapping band can be calculated according to the following formula in step S1:

[0055] F2 = F1 / m

[0056] In the formula, F2 represents the theoretical pre-tightening force of the strapping band, m represents the number of strapping bands; F1 represents the pre-tightening force required for the battery module.

[0057] In an alternative embodiment, when performing a tensile test on the strapping band, at least two sets of strapping bands with different widths are selected for the tensile test. Specifically, when selecting the width of the strapping band, the widths that will be used in the actual production process can be selected, such as strapping bands with widths of 19 mm, 23 mm, and 30 mm, so that the tensile test can better represent the actual situation.

[0058] In an alternative embodiment, when performing a tensile test on the strapping band, the length of the strapping band is less than or equal to 1 m. This range matches the length range of the strapping band used in actual use and can ensure that the data obtained from the tensile test matches the actual situation.

[0059] In an alternative embodiment, when performing a tensile test on the strapping band, the tensile force applied to the strapping band is less than or equal to 1000 kgf.

[0060] In an alternative embodiment, the linear coefficient of the strapping band is calculated according to the following formula:

[0061]

[0062] In the formula, K represents the linear coefficient of the strapping band; ΔL represents the deformation amount when the strapping band is stretched, and F represents the tensile force applied to the strapping band.

[0063] In an alternative embodiment, the range of the predetermined interval is that the linear coefficient is greater than or equal to 0.001 and less than or equal to 0.004, that is, 0.001 ≤ K ≤ 0.004.

[0064] In an alternative embodiment, in step S4, the corrected length of the strapping is calculated according to the following formula:

[0065] L = L1 - KF2

[0066] In the formula, L represents the corrected length of the strapping.

[0067] In an alternative embodiment, after obtaining the linear coefficient, the linear coefficient and the predetermined interval are amplified using the amplification coefficient; when calculating the corrected length, the theoretical geometric length is subtracted by the product of the theoretical pre-tightening force, the linear coefficient, and the reciprocal of the amplification coefficient; the amplification coefficient is divisible by 50. That is, in step S2, the linear coefficient of the strapping is calculated using the following formula:

[0068]

[0069] In the formula, V represents the amplification coefficient, V = 50, 100, 150...

[0070] Correspondingly, the range of the predetermined interval should be expanded to that the linear coefficient is greater than or equal to 0.05 and less than or equal to 0.2, that is, 0.05 ≤ K ≤ 0.2.

[0071] Correspondingly, in step S4, the corrected length of the strapping is calculated according to the following formula:

[0072] L = L1 - KF2 / V

[0073] In an alternative embodiment, if the size specification or the required pre-tightening force of the battery module changes, step S1 is re-performed to calculate the new theoretical geometric length and the theoretical pre-tightening force, and then it jumps to step S4 to recalculate the length of the strapping, without repeating steps S2 to S3.

[0074] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining the length of a battery module binding strap, characterized in that, It includes the following steps: S1. Calculate the theoretical geometric length of the bundling strap according to the geometric dimensions of the battery module; calculate the theoretical pre-tightening force of the bundling strap according to the pre-tightening force requirement of the battery module; S2. Conduct a tensile test on the bundling strap to obtain the linear coefficient between the deformation of the bundling strap and the tensile force; S3. Determine whether the linear coefficient is within a predetermined range. If so, jump to step S4; if not, change the material of the bundling strap and repeat steps S2 to S3; S4. Correct the theoretical geometric length according to the product of the theoretical pre-tightening force and the linear coefficient to obtain the corrected length of the bundling strap; S5. When the size specification or the required pre-tightening force of the battery module changes, re-perform step S1 to calculate the new theoretical geometric length and the new theoretical pre-tightening force, and then jump to step S4 to recalculate the length of the bundling strap.

2. The method for determining the length of a battery module binding band according to claim 1, wherein Calculate the corrected length of the bundling strap according to the following formula: In the formula, represents the corrected length of the strapping; represents the theoretical geometric length of the strapping; represents the theoretical pre-tightening force of the strapping; represents the linear coefficient of the strapping.

3. The method for determining the length of a battery module bundling strap according to claim 1, characterized in that, Calculate the linear coefficient of the bundling strap according to the following formula: In the formula, represents the linear coefficient of the binding band; represents the deformation amount when the binding band is stretched, represents the tensile force applied to the binding band.

4. The method for determining the length of a battery module binding strap according to claim 1, wherein, The range of the predetermined range is that the linear coefficient is greater than or equal to 0.001 and less than or equal to 0.

004.

5. A method for determining the length of a battery module binding strap according to any one of claims 1 to 4, characterized in that When conducting the tensile test on the bundling strap, select at least two groups of the bundling straps with different widths for the tensile test.

6. A method for determining the length of a battery module bundling strap according to any one of claims 1 to 4, characterized in that, When conducting the tensile test on the bundling strap, the tensile force applied to the bundling strap is less than or equal to 1000 kgf.

7. A method for determining the length of a battery module binding strap according to any one of claims 1 to 4, characterized in that Calculate the theoretical pre-tightening force of the bundling strap according to the following formula: In the formula, represents the theoretical pre-tightening force of the strapping; represents the number of the strappings; represents the pre-tightening force required for the battery module.

8. A method for determining the length of a battery module bundling strap according to any one of claims 1 to 4, characterized in that, Calculate the theoretical geometric length of the bundling strap according to the following formula: In the formula, represents the theoretical geometric length of the strapping band; represents the thickness of the battery cells in the battery module, represents the gap between the battery cells, represents the number of the battery cells; represents the thickness of the end plate in the battery module, represents the thickness of the insulating sheet of the end plate.

9. A method for determining the length of a battery module bundling strap according to any one of claims 1 to 4, characterized in that, After obtaining the linear coefficient, use the magnification factor to magnify the linear coefficient and the predetermined range; when calculating the corrected length, subtract the product of the theoretical pre-tightening force, the linear coefficient and the reciprocal of the magnification factor from the theoretical geometric length; the magnification factor is divisible by 50.

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