CTC power battery system and design method

Abstract

The present application relates to a kind of CTC power battery systems and design method, system is by bottom guard plate, battery cell, bottom glue, elastic medium, side glue, middle support bracket, box and liquid cooling plate constitute;Battery cell is fixed by bottom glue, side glue, middle support bracket and liquid cooling plate and box;When battery cell and box are bonded by side glue, glue layer thickness is controlled by limiting strip, and elastic medium is added between battery cell;Battery cell is connected with box by middle support bracket, and support bracket has matching surface feature;Box is composed of frame and middle longitudinal beam, and frame and middle longitudinal beam all have adhesive plane, respectively adhesive plane I, adhesive plane II, and adhesive plane II of frame cannot invade battery cell under collision condition.The present application can be designed on the premise that the thermal runaway protection capability is not reduced, and the general battery cell is used for CTC battery scheme;Design idea follows mature scheme of non-CTC battery, and the change of parts is small, and it does not involve excessive tool change.

Description

Technical Field

[0001] This invention belongs to the field of power battery technology, specifically relating to a CTC power battery system and its design method. Background Technology

[0002] CTC, short for Cell to Chassis, is one of the latest research directions in electric vehicle power batteries. CTC abandons the concept of a battery pack, directly integrating the battery cell with the chassis design. The application of CTC technology will effectively reduce weight, reduce intermediate processes and components, and the space saved by reducing components can accommodate more batteries, thereby increasing driving range. This technology is also considered a major direction for the future of electric vehicles, and many automakers have proposed CTC technology roadmaps.

[0003] To improve integration efficiency, the CTC solution integrates the battery cover and the vehicle floor into a single component. However, this also reduces thermal runaway protection, necessitating additional design features to ensure the safety of the passenger compartment above the battery. Protection can be achieved by adding extra components such as aerogel or asbestos sheets, but this reduces assembly efficiency and increases costs. Alternatively, the orientation of the cell's explosion-proof valve could be changed, but this modification incurs significant development costs and a lengthy development cycle. Summary of the Invention

[0004] The purpose of this invention is to provide a CTC power battery system and a design method for a CTC power battery system, so as to solve the problem of designing CTC batteries using general-purpose cells without reducing thermal runaway protection capabilities.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A CTC power battery system comprises a bottom protective plate 1, a battery cell 2, bottom adhesive 3, an elastic medium 4, side adhesive 5, a central support bracket 6, a housing 7, and a liquid cooling plate 8.

[0007] The explosion-proof valve of the battery cell 2 is arranged upside down. The battery cell 2 is connected and fixed to the liquid cooling plate 8 and the housing 7 through the bottom glue 3, the side glue 5, and the middle support bracket 6.

[0008] When the battery cell 2 and the housing 7 are bonded together with the side adhesive 5, the thickness of the adhesive layer is controlled by the limiting strip 11. The thickness of the limiting strip is in the range of 0.2mm-2mm, and an elastic medium 4 is added between the battery cells 2.

[0009] The battery cell 2 is connected to the housing 7 via a central support bracket 6. The support bracket 6 has a mating surface feature 32, which is processed to improve the insulation level of the battery system.

[0010] The housing 7 is composed of a frame 42 and a central longitudinal beam 41. Both the frame 42 and the central longitudinal beam 42 have adhesive surfaces, namely adhesive surface I 45 and adhesive surface II 46, respectively. The adhesive surface II 46 of the frame 42 has a certain energy absorption space from the inner side surface 47 of the frame 42, so that when a squeezing collision occurs, the adhesive surface II 46 of the frame 42 will not penetrate the battery cell 2.

[0011] Furthermore, the battery cell 2 is a square battery cell with part of the blue film removed from the bottom.

[0012] Furthermore, the elastic medium 4 is bonded to the battery cell 2 with double-sided adhesive.

[0013] Furthermore, the elastic medium 4 must have good thermal insulation properties.

[0014] Furthermore, the battery cell 2 is bolted or riveted to the housing 7 via the central support bracket 6.

[0015] Furthermore, the mating surface feature 32 is treated by powder coating or by pasting an insulating film.

[0016] Furthermore, a 1mm-3mm gap is reserved between the mating surface feature 32 and the cell end face 31.

[0017] Furthermore, the mating surface feature 32 and the cell end face 31 are filled with an elastic medium 4 or glue to absorb tolerances.

[0018] Furthermore, the width of the energy-absorbing space is in the range of 15mm-45mm.

[0019] A design method for a CTC power battery system includes the following steps:

[0020] A. Take the layout boundaries of the battery system, cell size, and performance requirements as inputs;

[0021] B. Determine the number of battery modules based on the layout boundary and performance requirements of the battery system. Calculate the battery module size based on the cell size. The battery module size should be less than 80% of the corresponding boundary. The combined performance parameters of the individual battery modules should be greater than 110% of the performance requirements.

[0022] C. Calculate the width of the central longitudinal beam 41 and the gap between the adhesive plane II 46 of the frame 42 and the inner side 47 of the frame 42 based on the battery module size and boundary size. The width of the central longitudinal beam 41 is 20mm-40mm, and the gap of the adhesive plane of the frame is 1%-3% of the total width.

[0023] D. Calculate the thickness of elastic medium 4 based on the dimensional tolerances of each component in the width direction of the battery module. The thickness of elastic medium 4 is 1.1 * the statistical tolerance value of the width of each component.

[0024] E. Calculate the thickness of the limiting strip 11 based on the dimensional tolerances of the battery cell 2 and the housing 7. The thickness of the limiting strip 11 is 1.1 * the statistical tolerance value of the battery cell and the housing. The thickness of the limiting strip 11 should be in the range of 0.2mm-2mm.

[0025] F. Calculate the thickness of the bottom adhesive 3 based on the dimensional tolerances of the battery cell 2 and the liquid cooling plate 8. The thickness of the bottom adhesive 3 is 1.1 * the statistical tolerance value of the battery cell and the liquid cooling plate. The thickness of the bottom adhesive 3 should be in the range of 0.5mm-2mm.

[0026] G. Perform structural strength verification on the battery pack.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] The present invention relates to a CTC power battery system and design method, which can design a CTC battery scheme using general-purpose cells without reducing the thermal runaway protection capability. The design concept follows the mature scheme of non-CTC batteries, with minimal changes to components and minimal changes to tooling. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A schematic diagram of the CTC power battery system of this invention;

[0031] Figure 2 A schematic diagram showing the bonding of the battery cell to the casing using side adhesive;

[0032] Figure 3 A schematic diagram showing the connection between the battery cell and the housing via a central support bracket.

[0033] Figure 4 Schematic diagram of the box structure.

[0034] In the diagram: 1. Bottom protective plate; 2. Battery cell; 3. Bottom adhesive; 4. Elastic medium; 5. Side adhesive; 6. Central support bracket; 7. Housing; 8. Liquid cooling plate; 11. Limiting strip; 31. Battery cell end face; 32. Mating surface features; 41. Central longitudinal beam; 42. Frame; 45. Adhesive plane I; 46. Adhesive plane II; 47. Inner side. Detailed Implementation

[0035] The present invention will be further described below with reference to embodiments:

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0037] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0038] In traditional battery packs, square cells are inserted into the pack from the top of the casing either in modular form or individually. In this case, the explosion-proof valve is applied to the bottom of the cell and bonded to the liquid cooling plate for structural fixation and cooling. However, for CTC batteries, the battery cover is integrated with the vehicle floor as a single component. If the traditional upward-facing explosion-proof valve design is still used, in the event of thermal runaway, debris from the cell could directly splash onto or melt through the upper protection, posing a risk to occupants. Therefore, this risk needs to be mitigated in the design.

[0039] like Figure 1 As shown, the CTC power battery system of the present invention consists of a bottom protective plate 1, a battery cell 2, a bottom adhesive 3, an elastic medium 4, a side adhesive 5, a central support bracket 6, a housing 7, and a liquid cooling plate 8.

[0040] The battery cell 2 is a square battery cell. To increase the bonding effect, part of the blue film is removed from the bottom of the battery cell 2. The explosion-proof valve of the battery cell 2 is arranged upside down. The battery cell 2 is connected and fixed to the liquid cooling plate 8 and the box body 7 through the bottom glue 3, the side glue 5, and the middle support bracket 6.

[0041] like Figure 2 As shown, when the battery cell 2 and the housing 7 are bonded together with the side adhesive 5, the thickness of the adhesive layer is controlled by the limiting strip 11 to achieve the best bonding performance. The thickness of the limiting strip is in the range of 0.2mm-2mm. At the same time, in order to absorb the tolerance and ensure that the battery cell 2 and the limiting strip 11 are in contact, an elastic medium 4 is added between the battery cells 2. The elastic medium 4 and the battery cell 2 are bonded together with double-sided adhesive. The elastic medium 4 must have good thermal insulation performance to prevent thermal diffusion between adjacent battery cells in the event of thermal runaway.

[0042] like Figure 3As shown, the battery cell 2 is connected to the housing 7 via a central support bracket 6. The connection method can be bolted or riveted. The support bracket 6 has a mating surface feature 32, which is treated by powder coating or pasting an insulating film to improve the insulation level of the battery system. A 1mm-3mm gap is reserved between the mating surface feature 32 and the end face 31 of the battery cell, and is filled with an elastic medium or glue to absorb the tolerance.

[0043] like Figure 4 As shown, the housing 7 is composed of a frame 42 and a central longitudinal beam 41. Both the frame 42 and the central longitudinal beam 42 have adhesive surfaces, namely adhesive surface I 45 and adhesive surface II 46, respectively. The adhesive surface II 46 of the frame 42 needs to have a certain energy-absorbing space from the inner side 47 of the frame 42 to prevent the adhesive surface II 46 of the frame 42 from penetrating the battery cell 2 during squeezing or collision. The width of the energy-absorbing space is in the range of 15mm-45mm.

[0044] The design method of the CTC power battery system of the present invention includes the following steps:

[0045] Step 1: Input the layout boundaries of the battery system, cell 2 dimensions, and performance requirements;

[0046] Step 2: Determine the number of battery modules based on the layout boundary and performance requirements of the battery system. Calculate the battery module size based on the cell size. The battery module size should be less than 80% of the corresponding boundary, and the sum of the individual performance parameters of the battery modules should be greater than 110% of the performance requirements.

[0047] Step 3: Calculate the width of the central longitudinal beam 41 and the gap between the adhesive plane II 46 of the frame 42 and the inner side 47 of the frame 42 based on the battery module size and boundary size. The width of the central longitudinal beam 41 is 20mm-40mm, and the gap of the adhesive plane of the frame is 1%-3% of the total width.

[0048] Step 4: Calculate the thickness of the elastic medium 4 based on the dimensional tolerances in the width direction of each component of the battery module. The thickness of the elastic medium 4 is 1.1 * the statistical tolerance value of the width of each component.

[0049] Step 5: Calculate the thickness of the limiting strip 11 based on the dimensional tolerances of the battery cell 2 and the housing 7. The thickness of the limiting strip 11 is 1.1 * the statistical tolerance value of the battery cell and the housing. At the same time, to ensure the bonding performance, the thickness of the limiting strip 11 should be in the range of 0.2mm-2mm.

[0050] Step 6: Calculate the thickness of the bottom adhesive 3 based on the dimensional tolerances of the battery cell 2 and the liquid cooling plate 8. The thickness of the bottom adhesive 3 is 1.1 * the statistical tolerance value of the battery cell and the liquid cooling plate. At the same time, to ensure bonding performance, the thickness of the bottom adhesive 3 should be in the range of 0.5mm-2mm.

[0051] Step 7: Perform structural strength verification on the battery pack.

[0052] Example 1

[0053] A CTC power battery system comprises a bottom protective plate 1, a battery cell 2, a bottom adhesive 3, an elastic medium 4, a side adhesive 5, a central support bracket 6, a housing 7, and a liquid cooling plate 8.

[0054] The battery cell 2 is a square battery cell with part of the blue film removed from its bottom. The explosion-proof valve of the battery cell 2 is arranged upside down. The battery cell 2 is connected and fixed to the liquid cooling plate 8 and the housing 7 by bottom glue 3, side glue 5, and middle support bracket 6.

[0055] When the battery cell 2 is bonded to the housing 7 using side adhesive 5, the adhesive layer thickness is controlled by the limiting strip 11. An elastic medium 4 is added between the battery cells 2, and the elastic medium 4 is bonded to the battery cells 2 using double-sided adhesive.

[0056] The battery cell 2 is bolted to the housing 7 via a central support bracket 6. The support bracket 6 has a mating surface feature 32, which is powder coated. A 1mm-3mm gap is reserved between the mating surface feature 32 and the end face 31 of the battery cell, and is filled with an elastic medium 4.

[0057] The housing 7 is composed of a frame 42 and a central longitudinal beam 41. Both the frame 42 and the central longitudinal beam 42 have adhesive surfaces, namely adhesive surface I 45 and adhesive surface II 46, respectively. The adhesive surface II 46 of the frame 42 has a certain energy absorption space from the inner side surface 47 of the frame 42, so that when a squeezing collision occurs, the adhesive surface II 46 of the frame 42 will not penetrate the battery cell 2.

[0058] The design method of the CTC power battery system of the present invention includes the following steps:

[0059] Step 1: Input the layout boundaries of the battery system, cell 2 dimensions, and performance requirements;

[0060] Step 2: Determine the number of battery modules based on the layout boundary and performance requirements of the battery system. Calculate the battery module size based on the cell size. The battery module size should be less than 80% of the corresponding boundary, and the sum of the individual performance parameters of the battery modules should be greater than 110% of the performance requirements.

[0061] Step 3: Calculate the width of the central longitudinal beam 41 and the gap between the adhesive plane II 46 of the frame 42 and the inner side 47 of the frame 42 based on the battery module size and boundary size. The width of the central longitudinal beam 41 is 30mm, and the gap of the adhesive plane of the frame is 1% of the total width.

[0062] Step 4: Calculate the thickness of the elastic medium 4 based on the dimensional tolerances in the width direction of each component of the battery module. The thickness of the elastic medium 4 is 1.1 * the statistical tolerance value of the width of each component.

[0063] Step 5: Calculate the thickness of the limiting strip 11 based on the dimensional tolerances of battery cell 2 and housing 7. The thickness of the limiting strip 11 is 1.1 * the statistical tolerance value of the battery cell and housing; the thickness of the limiting strip 11 should be 0.5mm.

[0064] Step 6: Calculate the thickness of the bottom adhesive 3 based on the dimensional tolerances of the battery cell 2 and the liquid cooling plate 8. The thickness of the bottom adhesive 3 is 1.1 * the statistical tolerance value of the battery cell and the liquid cooling plate; the thickness of the bottom adhesive 3 should be 0.8mm.

[0065] Step 7: Perform structural strength verification on the battery pack.

[0066] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A CTC kinetic battery system, characterized by: It is composed of bottom protection plate (1), battery cell (2), bottom glue (3), elastic medium (4), side glue (5), middle support bracket (6), box (7) and liquid cooling plate (8); The explosion-proof valve of the battery cell (2) is arranged upside down, and the battery cell (2) is connected and fixed with the liquid cooling plate (8) and the box (7) through the bottom glue (3), the side glue (5) and the middle support bracket (6); When the battery cell (2) and the box (7) are bonded through the side glue (5), the thickness of the glue layer is controlled through the limiting strip (11), the thickness of the limiting strip is in the range of 0.2mm-2mm, and the elastic medium (4) is added between the battery cells (2); The battery cell (2) is connected with the box (7) through the middle support bracket (6), the support bracket (6) has a matching surface feature (32), and the matching surface feature (32) is processed to improve the insulation level of the battery system; The box (7) is composed of a frame (42) and a middle longitudinal beam (41), and the frame (42) and the middle longitudinal beam (41) both have adhesive planes, which are adhesive plane I (45) and adhesive plane II (46), respectively. The adhesive plane (46) of the frame (42) has a certain energy absorption space from the inner side (47) of the frame (42), so that when a crushing collision occurs, the adhesive plane II (46) of the frame (42) does not invade the battery cell (2); The battery cell (2) is a square battery cell with part of the blue film removed from the bottom; the elastic medium (4) and the battery cell (2) are bonded by double-sided adhesive; the elastic medium (4) needs to have good heat insulation performance; the battery cell (2) is bolted or riveted with the box (7) through the middle support bracket (6); the matching surface feature (32) is processed by powder spraying or pasting insulation film; the matching surface feature (32) and the battery cell end face (31) have a gap of 1mm-3mm; the matching surface feature (32) and the battery cell end face (31) are filled with elastic medium (4) or glue to absorb the tolerance; the width of the energy absorption space is in the range of 15mm-45mm.

2. A design method of a CTC power battery system according to claim 1, characterized in that, It includes the following steps: A, the arrangement boundary of the battery system, the size and performance requirements of the battery cell (2) are taken as input; B, according to the arrangement boundary and performance requirements of the battery system, the number of battery modules is determined, the size of the battery module is calculated according to the size of the battery cell, the size of the battery module is less than 80% of the corresponding boundary, and the performance parameters of the battery module are greater than 110% of the performance requirements; C, the width of the middle longitudinal beam (41) and the gap between the adhesive plane II (46) of the frame (42) and the inner side (47) of the frame (42) are calculated according to the size of the battery module and the boundary size, the width of the middle longitudinal beam (41) is 20mm-40mm, and the gap between the adhesive planes of the frame is 1%-3% of the total width; D, the thickness of the elastic medium (4) is calculated according to the width direction size tolerance of each part of the battery module, and the thickness of the elastic medium (4) is 1.1 times the statistical tolerance value of the width of each part. E、Through the size tolerance of the battery cell (2) and the box 7, the thickness of the limiting strip (11) is calculated, and the thickness of the limiting strip (11) is 1.1*the statistical tolerance value of the battery cell and the box; the thickness of the limiting strip (11) should be in the range of 0.2mm-2mm; F、Through the size tolerance of the battery cell (2) and the liquid cooling plate (8), the thickness of the bottom glue (3) is calculated, and the thickness of the bottom glue (3) is 1.1*the statistical tolerance value of the battery cell and the liquid cooling plate; the thickness of the bottom glue (3) should be in the range of 0.5mm-2mm; G、The structural strength of the battery pack is checked.

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