Model selection and checking method of fixed pull rod for battery module

Abstract

The invention provides a model selection and checking method of a fixed pull rod for a battery module. The model selection and verification method of the fixed pull rod for the battery module comprises the following steps: step S10, setting environmental parameters and attribute parameters of the fixed pull rod; s20, to-be-obtained parameters of the fixed pull rod are set; s30, acquiring a safety coefficient eta and a supporting surface contact stress sigma b; and S40, judging whether the safety coefficient eta is greater than or equal to a preset coefficient [eta] and whether the contact stress sigma b of the supporting surface is greater than or equal to the allowable stress sigma a of the supporting surface, if so, executing a step S50 of obtaining the parameters to be obtained, and if not, executing a step S20. According to the technical scheme, the model selection and checking method of the fixed pull rod for the battery module can not only avoid the problems that the model selection cost is high, the time is long and the development cycle requirement of a product is difficult to meet, but also avoid the problem of improper model selection caused by model selection only according to experience, so that the test failure risk rate can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of selection of fixed pull rods, and in particular to a method for selecting and checking fixed pull rods for battery modules. Background Art

[0002] With the rapid development of new energy vehicles, market competition is intensifying, and new vehicle models are constantly evolving. This has led to increasingly stringent requirements from OEMs for power battery development cycles. The existing short-term, quick-turnaround product development model has forced us to accelerate the development cycle of power battery systems, especially the time-consuming and costly simulation analysis of module mounting rods. Therefore, we urgently need to find a fast, convenient, and highly operational algorithm to assist in the design of power battery system structures.

[0003] In the existing technology, when selecting the specifications and quantity of the fixed tie rods for the battery system, firstly, most technicians generally select them based on experience, which often leads to failure of the fixed tie rods during product vibration tests and a high risk of test failure. Secondly, in each selection of the fixed tie rods, technicians model the fixed tie rods and perform simulation analysis to select the fixed tie rods. However, this leads to high costs and a long time, which cannot keep up with the requirements of the product development cycle. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for selecting and verifying fixed pull rods for battery modules. The above-mentioned method for selecting and verifying fixed pull rods for battery modules can not only avoid the problems of high selection cost, long time and difficulty in meeting product development cycle requirements, but also avoid the problem of improper selection caused by selection based solely on experience, thereby reducing the risk rate of test failure.

[0005] In order to achieve the above-mentioned object, the present invention provides a method for selecting and verifying a fixed tie rod for a battery module, comprising: step S10: setting environmental parameters and property parameters of the fixed tie rod; step S20: setting parameters to be obtained for the fixed tie rod; step S30: obtaining a safety factor η and a support surface contact stress σ b ; Step S40: Determine whether the safety factor η is greater than or equal to the preset coefficient [η], and the support surface contact stress σ b Is it greater than or equal to the allowable stress σ of the support surface? a If yes, then execute step S50 of obtaining the parameters to be obtained; if no, execute step S20. In the above technical solution, by setting the environmental parameters and the property parameters of the fixed pull rod, and then setting the parameters to be obtained, the safety factor η and the support surface contact stress σ are calculated based on the environmental parameters, the property parameters and the parameters to be obtained. b , in order to be able to analyze the performance of the fixed tie rod under specific conditions, and then use the safety factor η and the support surface contact stress σb Make subsequent judgments to ensure the safety and reliability of the tie rod design. In this way, in the process of selecting each fixed tie rod, technicians only need to input environmental parameters and attribute parameters, and then select the parameters to be obtained for the fixed tie rod according to experience to obtain the safety factor η and the support surface contact stress σ b And verify it. Not only does it not need to establish a force analysis model of the fixed pull rod every time selection is made, so as to avoid the problems of high selection cost, long time and difficulty in meeting the requirements of the product development cycle, but it can also avoid the problem of improper selection caused by selection based solely on experience, thereby reducing the risk rate of test failure.

[0006] Furthermore, the fixed rod includes a nut and a screw connected to the nut, the environmental parameters include the torque M acting on the fixed rod, the parameters to be obtained include the pitch P and the nominal diameter D of the screw, and the property parameters include the friction coefficient u of the nut G and the friction coefficient u of the screw k Before step S30 and after step S20, the selection and verification method for the fixed tie rod for the battery module further includes: step S51: obtaining the mean diameter D2 of the screw according to the pitch P and the nominal diameter D; step S52: obtaining the mean diameter D2 of the screw according to the torque M, the pitch P, the friction coefficient u G , friction coefficient u k In the above technical solution, when the environmental parameters such as the torque M acting on the fixed rod are known, the technicians select the screw pitch P and nominal diameter D based on experience, and combine the nut u G and screw u k The friction coefficient of the present invention can realize the accurate evaluation of the preload force F of the pull rod, thereby ensuring the stable fixation of the module in a dynamic environment. Among them, in step S51, according to the selected pitch P and nominal diameter D, the screw diameter D2 is calculated, and the accurate diameter D2 can be obtained. In this way, the real size of the thread contact surface can be obtained more accurately, providing a basis for the calculation of the preload force; then, step S52 comprehensively considers the torque M, pitch P, friction coefficient u G , friction coefficient u k and the mean diameter D2, thereby realizing the quantification of the preload force F, which directly affects the stability of the fixed tie rod when subjected to external loads. By introducing the conversion relationship between torque and preload force, it not only avoids the uncertainty brought by experience in traditional design, but also greatly reduces the cost and time of simulation analysis.

[0007] Furthermore, step S30 includes: step S31: obtaining the tangential force F1 on the screw according to the preload force F; step S32: obtaining the external force F borne by the screw 外力 , where the direction of the tangential force F1 and the external force F 外力The direction of the preload force F is opposite to the direction of the external force F 外力 Step S33: Calculate the safety factor η, safety factor η = F1 / F 外力 In the above technical solution, step S31 derives the tangential force F1 on the screw rod from the preload force F. This force is generated by the friction between the screw rod and the contact surface, and its magnitude is directly related to the stability of the bolt connection. Then, in step S32, the external force F1 perpendicular to the preload force direction borne by the screw rod is obtained. 外力 , F 外力 The weight of the battery module or external vibration is an important factor in evaluating the safety of the connection. Finally, step S33 calculates the safety factor η = F1 / F 外力 , provides intuitive quantitative indicators for measuring the stability and safety margin of the tie rod design when subjected to actual loads. In this way, by converting complex structural mechanics analysis into physical parameter calculations, fast and accurate selection and verification of fixed tie rods can be achieved, greatly improving design efficiency and reducing the probability of errors caused by lack of experience.

[0008] Furthermore, step S31 includes: k , preload force F and formula F1=u k F, the step of calculating the tangential force F1. In the above technical solution, based on the friction coefficient u k The tangential force calculation method enables engineers to consider the friction characteristics of the connection interface more carefully, thereby making more reasonable design selections, reducing the cost and time pressure brought by traditional reliance on experience or simulation analysis, and greatly reducing the risk of vibration test failure caused by improper design.

[0009] Furthermore, the parameters to be acquired also include the number of fixed rods n, and the environmental parameters include the weight of the battery module m. 模组 and the vibration equivalent inertia force g of the battery module; Step S32 includes: according to the weight m 模组 , vibration equivalent inertia force g, quantity n and formula F 外力 =3m 模组 g / n, calculate the external force F 外力 In the above technical solution, by calculating the external force F 外力 , designers can accurately assess the load that each fixed tie rod needs to bear under actual working conditions, avoiding problems such as unstable connection or over-design caused by insufficient or excessive number of tie rods. Especially in the power battery system of new energy vehicles, the weight and vibration characteristics of the battery module place strict requirements on the performance of the tie rod. Formula F 外力 =3m 模组g / n can help designers find the optimal balance between battery module weight, vibration characteristics and the number of tie rods, ensuring the stability of the connection structure in the face of high-frequency vibration and dynamic loads, and reducing the risk of test failure. By introducing a simple and effective calculation formula, it can quickly verify the performance of the fixed tie rods, allowing designers to complete multiple design iterations and parameter optimization in a short period of time, accelerating the battery module development cycle and reducing development costs.

[0010] Furthermore, in step S51 , the screw's median diameter D2 satisfies the formula: D2 = D - 0.6495 × P. In this way, the screw's median diameter D2 can be calculated.

[0011] Furthermore, in step S52, the preload force F satisfies the formula:

[0012] In the above technical solution, the preload force F is calculated by the above formula, which can achieve accurate and rapid calculation of the preload force of the fixed tie rod, avoiding the uncertainty caused by reliance on experience or rough estimation in traditional design.

[0013] Furthermore, step S30 further includes: step S34: obtaining the contact area A between the nut and the end plate S ; Step S35: According to the contact area A S and preload F, calculate the support surface contact stress σ b , where σ b =F / A S In the above technical solution, by quantifying the contact stress on the support surface, it is possible to accurately determine whether the support surface (usually the contact surface between the nut and the end plate) of the fixed tie rod connection is within a safe operating range when subjected to a preload, thereby avoiding material fatigue or connection failure caused by excessive contact surface stress.

[0014] Furthermore, the parameters to be acquired also include the contact outer diameter D of the nut. out Contact inner diameter D of the nut in Step S34 includes contacting the outer diameter D out and contact inner diameter D in , calculate the contact area A S , where A S =π(D out / 2) 2 -π(D out / 2) 2 In the above technical solution, the contact area A S The accurate calculation of the preload force F provides a basis for the uniform distribution of the preload force F on the support surface, ensuring the reasonable stress distribution at the contact interface between the nut and the end plate, and avoiding the connection failure or material damage caused by local stress concentration; and by comparing the contact stress σb By comparing the allowable stress of the material, designers can quickly identify potential deficiencies in the design, adjust the specifications or quantity of the fixing rods in a timely manner, and optimize the contact area to ensure that the connection does not become the weak link in the system.

[0015] Furthermore, the preset coefficient [η] is 2, and / or the support surface allowable stress σ a The pressure is 170Mpa. In this way, the fixed rod can be selected according to the above data.

[0016] By applying the technical solution of the present invention, by setting the environmental parameters and the attribute parameters of the fixed pull rod, and then setting the parameters to be obtained, the safety factor η and the support surface contact stress σ are calculated based on the environmental parameters, the attribute parameters and the parameters to be obtained. b , in order to be able to analyze the performance of the fixed tie rod under specific conditions, and then use the safety factor η and the support surface contact stress σ b Make subsequent judgments to ensure the safety and reliability of the tie rod design. In this way, in the process of selecting each fixed tie rod, technicians only need to input environmental parameters and attribute parameters, and then select the parameters to be obtained for the fixed tie rod according to experience to obtain the safety factor η and the support surface contact stress σ b And verify it. Not only does it not need to establish a force analysis model of the fixed pull rod every time selection is made, so as to avoid the problems of high selection cost, long time and difficulty in meeting the requirements of the product development cycle, but it can also avoid the problem of improper selection caused by selection based solely on experience, thereby reducing the risk rate of test failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 A schematic structural diagram of an embodiment of a battery of the present invention is shown;

[0019] Figure 2 Shown Figure 1 Schematic diagram of the force analysis of the fixed rod of the battery;

[0020] Figure 3 A schematic flow chart of an embodiment of a method for selecting and verifying a fixing tie rod for a battery module according to the present invention is shown.

[0021] The above drawings include the following reference numerals:

[0022] 1. Battery module; 2. Fixed pull rod; 3. Lower shell. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] Specifically, if Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a battery, which includes a battery module 1, a plurality of fixing rods 2 and a lower shell 3. The battery module 1 is fixed to the lower shell 3 through the plurality of fixing rods.

[0025] An embodiment of the present invention provides a method for selecting and verifying fixed tie rods for battery modules, which is used to solve the selection and verification of the specifications and quantity of fixed tie rods for fixed modules in the design of power battery systems, avoid the risk of test failure caused by design experience, and avoid the high cost and long cycle of simulation analysis.

[0026] like Figures 1 to 3 As shown, an embodiment of the present invention provides a method for selecting and verifying a fixed tie rod for a battery module, the method comprising: step S10: setting environmental parameters and property parameters of the fixed tie rod; step S20: setting parameters to be obtained for the fixed tie rod; step S30: obtaining a safety factor η and a support surface contact stress σ b ; Step S40: Determine whether the safety factor η is greater than or equal to the preset coefficient [η], and the support surface contact stress σ b Is it greater than or equal to the allowable stress σ of the support surface? a If yes, execute step S50 of obtaining the parameters to be obtained; if no, execute step S20.

[0027] In the above technical solution, by setting the environmental parameters and the property parameters of the fixed pull rod, and then setting the parameters to be obtained, the safety factor η and the support surface contact stress σ are calculated based on the environmental parameters, the property parameters and the parameters to be obtained. b , in order to be able to analyze the performance of the fixed tie rod under specific conditions, and then use the safety factor η and the support surface contact stress σ b Make subsequent judgments to ensure the safety and reliability of the tie rod design. In this way, in the process of selecting each fixed tie rod, technicians only need to input environmental parameters and attribute parameters, and then select the parameters to be obtained for the fixed tie rod according to experience to obtain the safety factor η and the support surface contact stress σ b And verify it. Not only does it not need to establish a force analysis model of the fixed pull rod every time selection is made, so as to avoid the problems of high selection cost, long time and difficulty in meeting the requirements of the product development cycle, but it can also avoid the problem of improper selection caused by selection based solely on experience, thereby reducing the risk rate of test failure.

[0028] Specifically, in an embodiment of the present invention, before step S10, the selection and verification method for a fixed tie rod for a battery module further includes: step S1: establishing a selection model for the fixed tie rod; in this way, environmental parameters and attribute parameters can be input into the selection model, parameters to be obtained can be selected based on experience and input into the selection model, and the safety factor η and the support surface contact stress σ can be calculated using the selection model. b , and then use the selection model to implement the judgment step and execute the subsequent steps. Among them, the environmental parameters and attribute parameters are parameters that can be directly obtained or calculated. The parameters to be obtained are the parameters selected by the technicians. It is judged whether the safety factor η is greater than or equal to the preset factor [η], and the support surface contact stress σ b Is it greater than or equal to the allowable stress σ of the support surface? a If yes, then the selected parameters to be obtained can be obtained to realize the selection of the fixed pull rod. If not, the technicians will reselect the parameters to be obtained and judge again until the safety factor η is greater than or equal to the preset factor [η] and the support surface contact stress σ b Greater than or equal to the allowable stress σ of the support surface a , and then obtain the selected parameters to be obtained.

[0029] In the embodiment of the present invention, the fixed rod includes a nut and a screw connected to the nut, the environmental parameters include the torque M acting on the fixed rod, the parameters to be acquired include the pitch P and the nominal diameter D of the screw, and the property parameters include the friction coefficient u of the nut. G and the friction coefficient u of the screw k Before step S30 and after step S20, the selection and verification method for the fixed tie rod for the battery module further includes: step S51: obtaining the mean diameter D2 of the screw according to the pitch P and the nominal diameter D; step S52: obtaining the mean diameter D2 of the screw according to the torque M, the pitch P, the friction coefficient u G , friction coefficient u k and the middle diameter D2 to obtain the preload force F acting on the fixed tie rod.

[0030] In the above technical solution, when the environmental parameters such as the torque M acting on the fixed rod are known, the technicians select the screw pitch P and nominal diameter D based on experience, combined with the nut u G and screw u k The friction coefficient of the present invention can realize the accurate evaluation of the preload force F of the pull rod, thereby ensuring the stable fixation of the module in a dynamic environment. Among them, in step S51, according to the selected pitch P and nominal diameter D, the screw diameter D2 is calculated, and the accurate diameter D2 can be obtained. In this way, the real size of the thread contact surface can be obtained more accurately, providing a basis for the calculation of the preload force; then, step S52 comprehensively considers the torque M, pitch P, friction coefficient u G , friction coefficient uk and the mean diameter D2, thereby realizing the quantification of the preload force F, which directly affects the stability of the fixed tie rod when subjected to external loads. By introducing the conversion relationship between torque and preload force, it not only avoids the uncertainty brought by experience in traditional design, but also greatly reduces the cost and time of simulation analysis.

[0031] It should be noted that, in the embodiment of the present invention, the fixing rod is controlled by the torque M, and the preload force F generated is used to constrain the reliability of the threaded connection.

[0032] It should be noted that, in the embodiment of the present invention, the torque M is the torque used to screw the fixed rod, the pitch P of the screw and the nominal diameter D of the screw are parameters selected by technicians, the friction coefficient uG of the nut and the friction coefficient uk of the screw are inherent parameters of the fixed rod, and the materials of the fixed rod are different, and the values ​​of the friction coefficient uG of the nut and the friction coefficient uk of the screw are different, which technicians can obtain based on experience; based on experience, it can be concluded that the range of the friction coefficient uG and the friction coefficient uk is usually 0.1-0.16.

[0033] In the embodiment of the present invention, step S30 includes: step S31: obtaining the tangential force F1 on the screw according to the preload force F; step S32: obtaining the external force F borne by the screw 外力 , where the direction of the tangential force F1 and the external force F 外力 The direction of the preload force F is opposite to the direction of the external force F 外力 Step S33: Calculate the safety factor η, safety factor η = F1 / F 外力 .

[0034] In the above technical solution, step S31 derives the tangential force F1 on the screw from the preload force F. This force is generated by the friction between the screw and the contact surface, and its magnitude is directly related to the stability of the bolt connection. Then, in step S32, the external force F1 perpendicular to the preload force direction borne by the screw is obtained. 外力 , F 外力 The weight of the battery module or external vibration is an important factor in evaluating the safety of the connection. Finally, step S33 calculates the safety factor η = F1 / F 外力 , provides intuitive quantitative indicators for measuring the stability and safety margin of the tie rod design when subjected to actual loads. In this way, by converting complex structural mechanics analysis into physical parameter calculations, fast and accurate selection and verification of fixed tie rods can be achieved, greatly improving design efficiency and reducing the probability of errors caused by lack of experience.

[0035] In the embodiment of the present invention, step S31 includes: k , preload force F and formula F1=uk F, the steps to calculate the tangential force F1.

[0036] In the above technical solution, based on the friction coefficient u k The tangential force calculation method enables engineers to consider the friction characteristics of the connection interface more carefully, thereby making more reasonable design selections, reducing the cost and time pressure brought by traditional reliance on experience or simulation analysis, and greatly reducing the risk of vibration test failure caused by improper design.

[0037] In the embodiment of the present invention, the parameters to be acquired also include the number of fixed rods n, and the environmental parameters include the weight of the battery module m. 模组 and the vibration equivalent inertia force g of the battery module; Step S32 includes: according to the weight m 模组 , vibration equivalent inertia force g, quantity n and formula F 外力 =3m 模组 g / n, calculate the external force F 外力 steps.

[0038] In the above technical solution, by calculating the external force F 外力 , designers can accurately assess the load that each fixed tie rod needs to bear under actual working conditions, avoiding problems such as unstable connection or over-design caused by insufficient or excessive number of tie rods. Especially in the power battery system of new energy vehicles, the weight and vibration characteristics of the battery module place strict requirements on the performance of the tie rod. Formula F 外力 =3m 模组 g / n can help designers find the optimal balance between battery module weight, vibration characteristics and the number of tie rods, ensuring the stability of the connection structure in the face of high-frequency vibration and dynamic loads, and reducing the risk of test failure. By introducing a simple and effective calculation formula, it can quickly verify the performance of the fixed tie rods, allowing designers to complete multiple design iterations and parameter optimization in a short period of time, accelerating the battery module development cycle and reducing development costs.

[0039] It should be noted that, in the embodiments of the present invention, the vibration equivalent inertia force g of the battery module can be obtained by those skilled in the art through testing.

[0040] In the embodiment of the present invention, in step S51, the screw's median diameter D2 satisfies the formula: D2 = D - 0.6495 × P. In this way, the screw's median diameter D2 can be calculated.

[0041] In the embodiment of the present invention, in step S52, the preload force F satisfies the formula:

[0042] Among them, D Kmis the contact surface friction radius, which is the equivalent radius of the contact surface between the nut of the fixed rod and the end plate of the battery module, that is, π(D Km / 2) 2 =The contact area between the nut and the end plate of the battery module.

[0043] In the above technical solution, the preload force F is calculated by the above formula, which can achieve accurate and rapid calculation of the preload force of the fixed tie rod, avoiding the uncertainty caused by reliance on experience or rough estimation in traditional design.

[0044] In the embodiment of the present invention, step S30 further includes: step S34: obtaining the contact area A between the nut and the end plate S ; Step S35: According to the contact area A S and preload F, calculate the support surface contact stress σ b , where σ b =F / A S .

[0045] In the above technical solution, by quantifying the contact stress of the support surface, it is possible to accurately determine whether the support surface (usually the contact surface between the nut and the end plate) of the fixed tie rod connection is within a safe operating range when it is subjected to preload, thereby avoiding material fatigue or connection failure caused by excessive contact surface stress.

[0046] In the embodiment of the present invention, the parameters to be obtained also include the contact outer diameter D of the nut out Contact inner diameter D of the nut in Step S34 includes contacting the outer diameter D out and contact inner diameter D in , calculate the contact area A S , where A S =π(D out / 2) 2 -π(D out / 2) 2 .

[0047] In the above technical solution, the contact area A S The accurate calculation of the preload force F provides a basis for the uniform distribution of the preload force F on the support surface, ensuring the reasonable stress distribution at the contact interface between the nut and the end plate, and avoiding the connection failure or material damage caused by local stress concentration; and by comparing the contact stress σ b By comparing the allowable stress of the material, designers can quickly identify potential deficiencies in the design, adjust the specifications or quantity of the fixing rods in a timely manner, and optimize the contact area to ensure that the connection does not become the weak link in the system.

[0048] It should be noted that, in the embodiment of the present invention, the contact surface between the nut and the end plate is an annular surface, and the contact outer diameter D of the nut isout Refers to the outer diameter of the annular surface, that is, the outer diameter of the nut; the contact inner diameter D of the nut in It refers to the inner diameter of the annular surface, that is, the aperture of the end plate.

[0049] In the embodiment of the present invention, the preset coefficient [η] is 2, and / or the support surface allowable stress σ a The pressure is 170Mpa. In this way, the fixed rod can be selected according to the above data.

[0050] It should be noted that the embodiment of the present invention converts the torque value M of the fixed rod into the preload force F, and further converts it into the force F1 of the fixed rod, so as to perform verification calculation quickly and conveniently.

[0051] It should be noted that in the embodiment of the present invention, the preset coefficient [η] is 2 and can be obtained based on experience, and the allowable stress σ of the support surface is a It can also be obtained based on experience; the allowable stress of the support surface is an inherent property of the material, for example, aluminum is generally 170 MPa, plastic is generally 45 MPa, and so on.

[0052] Table 1

[0053]

[0054] Specifically, as shown in Table 1, in this embodiment, the selection model is established using an EXCEL spreadsheet. Thus, through input adjustments to the EXCEL spreadsheet, designers only need to enter key parameters, such as module weight, system vibration equivalent inertia force, torque, bolt geometry parameters, and friction coefficient. The EXCEL spreadsheet can then quickly calculate all necessary data, including preload, tangential force, contact area, and support surface contact stress. Technicians can quickly evaluate the performance of tie rods of different specifications and quantities in response to factors such as system mass, vibration equivalent inertia force, and torque M acting on the fixed tie rods, ensuring that the final tie rod solution meets both safety and cost considerations while meeting strength and preload requirements. Furthermore, through the flexible use of the EXCEL spreadsheet, designers can quickly complete the evaluation and comparison of multiple tie rod specifications without having to conduct multiple fixed tie rod modeling analyses, thereby improving selection and verification efficiency.

[0055] The embodiments of the present invention provide a fast, convenient, and highly operable algorithm for solving the selection and verification of the specifications and quantity of the tie rods of the fixed module in the design of the power battery system, avoiding the risk of test failure caused by design experience, as well as the high cost and long cycle of simulation analysis, and realizing the selection and verification of the tie rod design in the structural design of the power battery system.

[0056] From the above description, it can be seen that the above embodiment of the present invention achieves the following technical effects: by setting the environmental parameters and the attribute parameters of the fixed pull rod, and then setting the parameters to be obtained, the safety factor η and the support surface contact stress σ are calculated based on the environmental parameters, the attribute parameters and the parameters to be obtained. b , in order to be able to analyze the performance of the fixed tie rod under specific conditions, and then use the safety factor η and the support surface contact stress σ b Make subsequent judgments to ensure the safety and reliability of the tie rod design. In this way, in the process of selecting each fixed tie rod, technicians only need to input environmental parameters and attribute parameters, and then select the parameters to be obtained for the fixed tie rod according to experience to obtain the safety factor η and the support surface contact stress σ b And verify it. Not only does it not need to establish a force analysis model of the fixed pull rod every time selection is made, so as to avoid the problems of high selection cost, long time and difficulty in meeting the requirements of the product development cycle, but it can also avoid the problem of improper selection caused by selection based solely on experience, thereby reducing the risk rate of test failure.

[0057] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for selecting and verifying a fixed tie rod for a battery module, characterized in that: include: Step S10: setting environmental parameters and property parameters of the fixed rod; Step S20: setting the parameters to be obtained for the fixed pull rod; Step S30: Obtain safety factor η and support surface contact stress σ b ; Step S40: Determine whether the safety factor η is greater than or equal to the preset factor [η], and whether the support surface contact stress σ b Is it greater than or equal to the allowable stress σ of the support surface? a If yes, then execute step S50 of obtaining the parameters to be obtained; if no, then execute step S20.

2. The method for selecting and checking the fixing rod for the battery module according to claim 1, characterized in that: The fixed rod includes a nut and a screw connected to the nut. The environmental parameters include the torque M acting on the fixed rod. The parameters to be acquired include the pitch P and the nominal diameter D of the screw. The property parameters include the friction coefficient u of the nut. G and the friction coefficient u of the screw k ; Before step S30 and after step S20, the method for selecting and verifying the fixing rod for the battery module further includes: Step S51: Obtaining the pitch diameter D2 of the screw according to the pitch P and the nominal diameter D; Step S52: According to the torque M, the pitch P, the friction coefficient u G , the friction coefficient u k and the middle diameter D2, to obtain the preload force F acting on the fixed rod.

3. The method for selecting and checking the fixing rod for the battery module according to claim 2, characterized in that: The step S30 includes: Step S31: obtaining the tangential force F1 acting on the screw according to the preload force F; Step S32: Obtain the external force F borne by the screw 外力 , wherein the direction of the tangential force F1 and the external force F 外力 The direction of the preload force F is opposite to the direction of the external force F 外力 The direction is set vertically; Step S33: Calculate the safety factor η, the safety factor η=F1 / F 外力 .

4. The method for selecting and checking the fixing rod for the battery module according to claim 3, characterized in that: The step S31 includes determining the friction coefficient u k , the preload force F and the formula F1=u k F, the step of calculating and obtaining the tangential force F1.

5. The method for selecting and checking the fixing rod for the battery module according to claim 3, characterized in that: The parameters to be acquired also include the number n of the fixed pull rods, and the environmental parameters include the weight m of the battery module. 模组 and the vibration equivalent inertia force g of the battery module; The step S32 includes: according to the weight m 模组 , the vibration equivalent inertia force g, the quantity n and formula F 外力 =3m 模组 g / n, calculate the external force F 外力 steps.

6. The method for selecting and checking the fixing rod for the battery module according to claim 2, characterized in that: In the step S51 , the median diameter D2 of the screw satisfies the formula: D2=D-0.6495×P.

7. The method for selecting and checking the fixing rod for the battery module according to claim 2, characterized in that: In step S52, the preload force F satisfies the formula:

8. The method for selecting and checking the fixing rod for the battery module according to claim 2, characterized in that: The step S30 further includes: Step S34: Obtain the contact area A between the nut and the end plate S ; Step S35: According to the contact area A S and the preload force F, calculate the support surface contact stress σ b , where σ b =F / A S .

9. The method for selecting and checking the fixing rod for the battery module according to claim 8, characterized in that: The parameters to be acquired also include the contact outer diameter D of the nut out and the contact inner diameter D of the nut in ; The step S34 includes determining the contact outer diameter D out and the contact inner diameter D in , calculate the contact area A S , where A S =π(D out / 2) 2 -π(D out / 2) 2 .

10. The method for selecting and checking the fixing rod for a battery module according to any one of claims 1 to 9, characterized in that: The preset coefficient [η] is 2, and / or the support surface allowable stress σ a It is 170Mpa.

Images