Battery box body and battery pack

Abstract

The battery box comprises a lower box body and an upper cover which are connected in a matched mode, the lower box body comprises a box body bottom plate, box body edge beams are symmetrically connected to the two long edges of the box body bottom plate, box body baffles are symmetrically connected to the two short edges of the box body bottom plate, and the box body baffles are connected with the ends of the box body edge beams. A boundary beam reinforcing rib is arranged on the inner side of the joint of the box body baffle and the box body boundary beam, and the two sides of the boundary beam reinforcing rib are connected with the box body baffle and the box body boundary beam in an arc welding mode; the top ends of the box body edge beam and the box body baffle plate are step-shaped and are mutually spliced to form an annular step for accommodating the sealing gasket; a plurality of battery cell expansion beams are arranged in the lower box body, the battery cell expansion beams are welded with the box body bottom plate and the box body edge beams, and battery cell modules are placed between the adjacent battery cell expansion beams; and the bottom of the lower box body is provided with buffer foam used for connecting a blade battery cell top cover in the battery cell module. The overall mechanical vibration strength is high, the safety of the battery pack is effectively guaranteed, and the service life of the battery pack is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of power batteries, and particularly relates to a battery box body and a battery pack. Background Art

[0002] The battery system device is mainly composed of components such as a battery box body, a battery module, a cell expansion beam, an electrical plastic bracket, an output pole seat, an output pole protection cover, a protection cover, a busbar, a low-voltage acquisition board, a low-voltage communication harness, a high-voltage power copper bar, a liquid cooling plate assembly, a liquid cooling pipeline assembly, a BCC, an FPC flexible circuit board, an explosion-proof breather valve, a manual maintenance switch, a high-voltage connector, a low-voltage connector, a gasket, a heat-conducting structural adhesive, a support plate, a module fixing bolt, a module support foam, and a single-strand blind rivet.

[0003] The current main requirements for battery packs in commercial vehicles are as follows:

[0004] Higher durability and safety reliability; commercial vehicles usually face more severe working environments, so the battery needs to have higher durability and safety reliability to ensure normal operation under various working conditions and ensure the long-term stable operation of the vehicle;

[0005] Cost-effectiveness: Commercial vehicle users are more sensitive to costs. The purchase cost and maintenance cost of the battery directly affect the operating profit. Therefore, while ensuring performance, the battery system needs to minimize costs as much as possible.

[0006] Higher energy density: The single-pack power of the battery pack is required to be higher, and more power is configured within a certain limited space. High energy density can reduce the number of battery cells, lower costs, and at the same time meet the commercial vehicle's demand for cruising range.

[0007] Fast charging ability: Commercial vehicles need to charge quickly to reduce operation interruption time. Efficient charging technology can significantly improve operation efficiency, reduce waiting time, and meet the high-efficiency operation requirements of commercial vehicles.

[0008] The current usage requirements of commercial vehicles for battery systems are getting higher and higher, which is also driving the gradual iterative upgrade of existing battery products to meet the real market demand. This has become an urgent key research direction to be solved at present.

[0009] Currently, there are the following common problems in the single-pack design of standard battery packs for commercial vehicles, specifically as follows:

[0010] The highest standard of mechanical vibration intensity generally meets the GB38031 standard and 1 times the GB / T31467.3 standard. It is difficult to meet the GB / T31467.3 standard or higher strength requirements at the battery system level. Therefore, there are certain deficiencies in meeting the operating conditions requirements of construction machinery products (the battery system needs to meet the requirements of 1 times GB / T31467.3 and above).

[0011] The weight energy density of the standard single cell generally ranges from 155 to 165 Wh / Kg. After forming a battery system, the weight energy density generally ranges from 105 to 115 Wh / kg. The low weight energy density at the battery system level has a certain impact on the vehicle's cruising range or working hours. A 10% reduction in the self-weight of an electric vehicle can increase the cruising range of the vehicle by about 5.5%.

[0012] The standard single cell sealing design structure is difficult to meet the IPX9K high-temperature and high-pressure test standard, the corrosion resistance life of materials, and the high cost of manufacturing gaskets.

[0013] The current design solution for the expansion force structure of the battery cell module inside the battery pack is difficult to meet the full life cycle of the battery pack. The number of battery cells in a single blade battery cell module is large, generally more than 50. This requires a higher expansion space for the battery cells. Generally, the expansion rate of a single battery cell is about 3%. The more battery cells there are, the greater the expansion force and the higher the risk. Therefore, when designing the battery cell module, the reasonable design of the number of battery cells needs to be considered.

[0014] With the continuous improvement of market requirements, customers have higher and higher requirements for the charging speed of the battery pack and the service life of the entire battery system. It generally requires charging to be completed within 0.5 hours (the charging rate of the battery cell is 2C), or even higher, within 0.25 hours (the charging rate of the battery cell is 4C). The service life of the battery system has been increased from the original 2800 times @ 70% SOH to ≥ 4500 times @ 70% SOH. Therefore, very high requirements are placed on the charging ability of the battery cells and the thermal management performance of the battery cells. Currently, the charging time of commercial vehicle battery packs is generally 2 hours (the charging rate of the battery cell is 0.5C) or 1 hour (the charging rate of the battery cell is 1C). To meet customer needs, corresponding solutions need to be provided. Summary of the Invention

[0015] The purpose of the present invention is to provide a battery box body and a battery pack with high overall mechanical vibration intensity, which can effectively ensure the safety of the battery pack and extend the service life of the battery pack.

[0016] To achieve the above object, the present invention provides a battery box body, which includes a lower box body and an upper cover that are connected in a matching manner. The lower box body includes a box body bottom plate. Box body side beams are symmetrically connected to the two long sides of the box body bottom plate, and box body baffles are symmetrically connected to the two short sides of the box body bottom plate. The box body baffles are connected to the ends of the box body side beams, and inner side beam reinforcing ribs are provided at the connection between the box body baffles and the box body side beams. The two sides of the inner side beam reinforcing ribs are connected to the box body baffles and the box body side beams by arc welding;

[0017] The tops of the box body side beams and the box body baffles are in a stepped shape, and they are spliced with each other to form an annular step for accommodating a sealing gasket;

[0018] A number of cell expansion beams are provided inside the lower box body. The cell expansion beams are welded to the box body bottom plate and the box body side beams, and a cell module is placed between adjacent cell expansion beams;

[0019] A buffer foam is provided at the bottom of the lower box body for connecting the top cover of the blade cell in the cell module.

[0020] As a further aspect of the present invention: The box body side beam is of an L-shaped structure and has a cavity inside. A horizontal reinforcing rib 1 is provided in the middle of the cavity, and inclined reinforcing ribs 1 that are perpendicular to each other are provided above and below the horizontal reinforcing rib 1.

[0021] As a further aspect of the present invention: A flow channel structure for passing coolant to perform liquid cooling and heat dissipation on the cell module is provided at the bottom of the box body side beam, and the flow channel inlet and outlet structure thereof adopts a form of inlet from both sides and outlet in the middle; The box body baffle has the same structure as the box body side beam.

[0022] As a further aspect of the present invention: The cell expansion beam is hollow inside and is provided with a number of horizontal reinforcing ribs 2. Inclined reinforcing ribs 2 are connected between adjacent horizontal reinforcing ribs 2, and the inclined reinforcing ribs 2 form an angle of 0° - 90° with the horizontal reinforcing ribs 2, and adjacent inclined reinforcing ribs 2 are symmetrically arranged.

[0023] As a further aspect of the present invention: The height of the annular step is lower than the thickness of the sealing gasket.

[0024] As a further aspect of the present invention: The box body bottom plate is formed by aluminum extrusion molding, and the internal cavity structure takes into account the cold plate flow channel for dissipating heat from the narrow surface of the blade cell. A stamping liquid cooling plate formed by stamping aluminum brazing process is correspondingly provided on the other narrow surface of the blade cell. The flow ports of the cold plate flow channel and the stamping liquid cooling plate are both in an S-shaped structure and adopt a form of inlet from both sides and outlet in the middle.

[0025] As a further aspect of the present invention: The inner surface of the box body bottom plate is sprayed with a heat preservation material, and the thickness of the heat preservation material is greater than 1 mm.

[0026] As a further aspect of the present invention: Insulating powder is sprayed on the surface of the heat preservation material, and the thickness of the insulating powder is greater than 60 μm.

[0027] A battery pack includes the above-mentioned battery box body and the battery module inside the battery box body.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The design structure of the box side beam is a cavity + three reinforcing ribs (horizontal reinforcing rib one, inclined reinforcing rib one). The upper and lower two reinforcing ribs form a 90-degree angle, and the middle reinforcing rib is horizontally designed, which can not only ensure the strength but also play a certain energy absorption role. In addition, a flow channel structure is provided at the bottom of the box side beam, which can be used to pass the coolant for liquid cooling and heat dissipation of the battery cell module, ensuring the safety of the battery and extending its service life;

[0030] Multiple groups of horizontal reinforcing ribs two and inclined reinforcing ribs two are arranged inside the battery cell expansion beam, which can not only improve the structural strength of the battery cell expansion beam but also play a role in weight reduction and lightening. The adjacent inclined reinforcing ribs two are symmetrically arranged, which is convenient for uniform strength stress and improving the service life of the extrusion die;

[0031] Adding side beam reinforcing ribs at the four corners inside the lower box body by arc welding can further strengthen the overall structural strength of the battery box body;

[0032] The top cover of the blade battery cell is arranged in the length direction of the battery cell. The weld of the battery cell top cover is at one side of the bottom of the box body. When the box body is subjected to external vibration excitation, it is easy to be transmitted to the weld of the battery cell top cover. When it lasts for a long time or the external excitation is large, it will cause the cracking of the weld, and finally lead to the leakage of the battery cell and cause a safety accident. The setting of the buffer foam can effectively achieve the buffering effect;

[0033] The overall structure of the gasket is simplified. It is integrally formed without installation holes, and its structural shape and thickness are closely related to the height of the annular step shape, ensuring the sealing performance of the battery box body. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural view of the lower box body of the present invention;

[0035] Figure 2 is a top view of the lower box body of the present invention;

[0036] Figure 2-1 is Figure 2 the A-A sectional view in

[0037] Figure 2-2 is Figure 2-1 the enlarged schematic view of part B in

[0038] Figure 3 is a schematic view of the box side beam of the present invention;

[0039] Figure 3-1 is Figure 3 the A-A sectional view in

[0040] Figure 3-2 is Figure 3 Schematic enlarged view of part B in

[0041] Figure 3-3 is the front view of the stamping liquid cooling plate;

[0042] Figure 3-4 is Figure 3-3 Schematic enlarged view of part C in

[0043] Figure 4 is the front view of the lower box body;

[0044] Figure 4-1 is the sectional view of the battery cell expansion beam;

[0045] Figure 5 is the partial axonometric view of the side beam reinforcing rib;

[0046] Figure 5-1 is the partial view of the side beam reinforcing rib;

[0047] Figure 6 is the axial view of the battery cell module layout;

[0048] Figure 6-1 is Figure 6 Schematic enlarged view of part D in

[0049] Figure 7 is the sectional view of the lower box body;

[0050] Figure 7-1 is Figure 7 Enlarged view of part C in

[0051] Figure 7-2 is the airtight test leakage air pressure drop diagram;

[0052] Figure 8 is the random vibration simulation structure diagram of the present invention.

[0053] In the figure: 1. Box body baffle, 2. Thermal insulation material, 3. Box body side beam, 4. Insulating powder, 5. Box body bottom plate, 6. Side beam reinforcing rib, 7. Sealing gasket, 8. Battery cell expansion beam, 9. Battery cell module, 10. Battery cell cooling plate, 11. Support foam, 12. Horizontal reinforcing rib 1, 13. Inclined reinforcing rib 1, 14. Flow channel structure, 15. Flow port, 16. Horizontal reinforcing rib 2, 17. Inclined reinforcing rib 2, 18. Buffer foam. Specific embodiments

[0054] The present invention will be further described below through embodiments.

[0055] Such as Figure 1As shown in the figure, a battery box body includes a lower box body and an upper cover that are connected in a matching manner. The lower box body is designed with a high-edge frame structure, and the overall height dimension of the box body is greater than the highest dimension of the battery cell (about 11 mm higher than the height of the battery cell. The purpose is to consider the dimensions of the cold plate 10 (H = 5.5 mm), glue (H = 1 mm), and support foam 11 (H = 3.5 mm) of the battery cell. The advantage is that the rigidity of the battery box body is higher, which greatly improves the protection of the battery cells inside the battery pack, and the overall natural frequency of the battery pack is also higher. For example, Figure 2 、 2-1 As shown in FIGS. 2-2, the lower box body includes a box body bottom plate 5. Two long sides of the box body bottom plate 5 are symmetrically connected with box body side beams 3, and two short sides of the box body bottom plate 5 are symmetrically connected with box body baffles 1. The box body baffles 1 are connected to the ends of the box body side beams 3, and inside the connection of the box body baffles 1 and the box body side beams 3, there are side beam reinforcing ribs 6. Both sides of the side beam reinforcing ribs 6 are connected to the box body baffles 1 and the box body side beams 3 by arc welding;

[0056] Furthermore, as Figures 3 to 3-4 shown, the box body side beam 3 is of an L-shaped structure with a cavity inside. In the middle of the cavity, there is a horizontal reinforcing rib 12, and above and below the horizontal reinforcing rib 12, there are inclined reinforcing ribs 13 that are perpendicular to each other; this can not only ensure the strength but also play a certain energy absorption role;

[0057] Furthermore, at the bottom of the box body side beam 3, there is a flow channel structure 14 for passing coolant to conduct liquid cooling and heat dissipation for the battery cell module 9, which ensures the safety of the battery and extends its service life. The flow channel inlet and outlet structure adopts a form of inlet from both sides and outlet in the middle, which can reduce the system pressure drop, lower the power of the liquid cooling unit, and effectively reduce costs; it improves the temperature field uniformity of the liquid cooling plate, reduces the temperature difference between single cells to within 3 °C, and extends the service life of the battery system; the box body baffle 1 has the same structure as the box body side beam 3;

[0058] The side beam reinforcing rib 6 is a trapezoidal extruded aluminum profile part, which effectively ensures the overall stiffness of the battery pack system. The designed wall thickness of the trapezoidal reinforcing rib is 2 mm, the internal included angle is designed to be 90 degrees, and it is parallel to the box body side beam 3, which improves the stress strength of the four lap joints of the box body and reduces the stress concentration at the welds. As Figure 5 、 5-1 shown;

[0059] The tops of the box body side beam 3 and the box body baffle 1 are in a stepped shape, and they are spliced with each other to form an annular step for accommodating the gasket 7;

[0060] Furthermore, the height of the annular step is lower than the thickness of the gasket 7. The design structure of the gasket 7 is simple and the cost is low. Compared with the existing gasket 7 products, the installation holes (generally dozens or hundreds of installation holes in the existing gasket 7) are eliminated. Canceling the installation holes can reduce the processing cost. At the same time, the width of the gasket is effectively controlled, and the overall material consumption is saved by about 50%, reducing the cost. Its structure is mainly related to the sealing structure design of the box body frame. The sealing structure of the box body side beam 3 is designed in a stepped shape, the step height is 2.5 mm, and the sealing width: ≥8 mm (IP68 sealing design requirement). The gasket 7 is installed in the area of the sunken step, and the upper plane is used as the compression ratio limit of the gasket 7. As Figure 7 、 7-1 shown. The thickness of the gasket 7 is designed to be 5 mm thick. Through the sealing calculation formula, we can get: W (compression rate) = (H o -H1) / H o ×100%, W (compression rate) = 50% (H0: total thickness 5 mm; H1: 2.5 mm). After the battery pack vibration test, the airtightness is tested, and the test result <50 pa, and the actual value is 19.2 pa. The test result far exceeds the standard (IP68 airtightness test standard, source enterprise standard box body sealing design specification) as Figure 7-2 shown;

[0061] Several cell expansion beams 8 are provided inside the lower box body. The cell expansion beams 8 are welded to the box body bottom plate 5 and the box body side beam 3. The cell modules 9 are placed between adjacent cell expansion beams 8;

[0062] Figure 1 As shown in Figure 4 、 4-1 shown, the inside of the cell expansion beam 8 is hollow and is provided with several horizontal reinforcing ribs II 16. An inclined reinforcing rib II 17 is connected between adjacent horizontal reinforcing ribs II 16. The inclined reinforcing rib II 17 forms an angle of 0°-90° with the horizontal reinforcing rib II 16, preferably 60°. Adjacent inclined reinforcing ribs II 17 are symmetrically arranged; the wall thickness of the cell expansion beam 8 and the thicknesses of the inclined reinforcing rib II 17 and the horizontal reinforcing rib II 16 inside the cross-section are designed to be 1.5 mm and 2 mm respectively, which can effectively carry out lightweight design; adding diagonal ribs inside the cross-section can effectively reduce the number of horizontal ribs, play a role in weight reduction and lightweight, and at the same time avoid insufficient strength and play an energy absorption role when the cells expand, preventing local stress damage to the cell surface; all the reinforcing rib design structures are symmetrically designed, which is convenient for uniform strength stress and improving the service life of the extrusion die; the above measures can also carry out lightweight design on the premise of effectively suppressing the cell expansion force, avoiding damage to the busbar weld strength and the FPC low-voltage acquisition system due to excessive expansion force;

[0063] A buffer foam 18 for connecting the top cover of the blade battery cells in the battery cell module 9 is provided at the bottom of the lower box body.

[0064] The structure of the blade battery cell is different from that of the ordinary square shell, soft package, and cylindrical single-core connector. The top cover of the blade battery cell is arranged in the length direction of the battery cell and is respectively arranged on the left and right sides (the top covers of the ordinary square shell, soft package, and cylindrical single-core battery cells are in the height direction). The laser welding process is used for welding the battery cell top cover and the shell. When designing the battery cell in the PACK box body, the weld of the battery cell top cover is at a certain distance from one side of the bottom of the box body. When the box body is subjected to external vibration excitation, it is easy to be transmitted to the weld of the battery cell top cover. When the time is long or the external excitation is large, it will cause the cracking of the weld, and finally lead to the leakage of the battery cell and cause a safety accident. Therefore, further buffering measures are needed. In addition, it can also take into account the limited glue thickness of the bottom glue, save the BOM of the limited glue strip materials, reduce the cost, and ensure the consistency of the glue thickness. The material density requirement of the buffer foam 18 is 200±30 g / cm3, and the 75% compression and rebound strength is about 80 kPa. The width of the buffer foam 18 is set to 20 mm, and the thickness is set to 4 mm (the weight of the battery cell module 9 is about 600 kg). Substituting into the calculation formula, we can get: P = F / S, P = 600*9.8 / 0.0744≈79 kPa (the 75% compression thickness is 1 mm), where 0.0744 is the area of the compressed buffer foam, as Figure 6 , 6-1 shown.

[0065] Furthermore, the box body bottom plate 5 is formed by aluminum extrusion. The internal cavity structure takes into account the cold plate flow channel for dissipating heat from one narrow side of the blade battery cell, and a stamping liquid cooling plate formed by stamping aluminum brazing process is correspondingly provided on the other narrow side of the blade battery cell. The flow ports 15 of the cold plate flow channel and the stamping liquid cooling plate are both in an S-shaped structure and adopt the form of inlet from both sides and outlet in the middle. The double-sided cooling of the battery cell is adopted to improve the temperature control effect on the battery cell.

[0066] Furthermore, a heat preservation material 2 is sprayed on the inner surface of the box body bottom plate 5, and the thickness of the heat preservation material 2 is greater than 1 mm. The heat preservation material 2 can keep the surface temperature of the battery cells inside the battery pack warm, reduce the temperature drop rate, and improve the user operation efficiency. Its process is to spray the liquid material mixture on the bottom of the box body or other areas with technical requirements, and directly bond it on the surface of the box body after air drying or natural drying. The adhesion meets the 1 mm cross-cut method, grade 0, and the inspection method is 《GB / T 9286-1998》. At the same time, it has the function of anti-corrosion protection for the surface of the box body.

[0067] Further, an insulating powder 4 is sprayed on the surface of the thermal insulation material 2, and the thickness of the insulating powder 4 is greater than 60 μm. The insulating powder 4 is used to prevent poor insulation and safety risks caused by the contact and conduction between the charged components inside the battery pack and the battery box body. An insulating protection coating needs to be added. The mixed liquid object is sprayed onto the technical requirement area inside the box body through spraying equipment. After high-temperature baking or natural drying, it is directly adhered to the box body surface, and the adhesion meets the 1mm cross-cut method, grade 0, and the inspection method is "GB / T 9286-1998". At the same time, it has the function of anti-corrosion and protection for the box body surface.

[0068] A battery pack includes the above-mentioned battery box body and the battery module inside the battery box body.

Claims

1. A battery box body, comprising a lower box body and an upper cover which are connected in a matching manner, characterized in that, The lower box body includes a box body bottom plate (5). Box body side beams (3) are symmetrically connected to the two long sides of the box body bottom plate (5), and box body baffles (1) are symmetrically connected to the two short sides of the box body bottom plate (5). The box body baffles (1) are connected to the ends of the box body side beams (3), and side beam reinforcing ribs (6) are provided inside the connection between the box body baffles (1) and the box body side beams (3). Both sides of the side beam reinforcing ribs (6) are connected to the box body baffles (1) and the box body side beams (3) by arc welding; The tops of the box body side beams (3) and the box body baffles (1) are in a stepped shape and are spliced with each other to form an annular step for accommodating a gasket (7); A number of cell expansion beams (8) are provided inside the lower box body. The cell expansion beams (8) are welded to the box body bottom plate (5) and the box body side beams (3), and a cell module (9) is placed between adjacent cell expansion beams (8); A buffer foam (18) for connecting the top cover of the blade cell in the cell module (9) is provided at the bottom of the lower box body.

2. The battery box according to claim 1, characterized in that, The box body side beam (3) is of an L-shaped structure and has a cavity inside. A horizontal reinforcing rib one (12) is provided in the middle of the cavity, and inclined reinforcing ribs one (13) perpendicular to each other are provided above and below the horizontal reinforcing rib one (12).

3. A battery box according to claim 1 or 2, characterized in that, A flow channel structure (14) for passing coolant to cool the cell module (9) by liquid cooling is provided at the bottom of the box body side beam (3), and the flow channel inlet and outlet structure thereof adopts a form of inlet from both sides and outlet in the middle; the box body baffle (1) has the same structure as the box body side beam (3).

4. A battery box according to claim 1, characterized in that, The cell expansion beam (8) is hollow inside and is provided with a number of horizontal reinforcing ribs two (16). Inclined reinforcing ribs two (17) are connected between adjacent horizontal reinforcing ribs two (16). The inclined reinforcing ribs two (17) form an angle of 0° - 90° with the horizontal reinforcing ribs two (16), and adjacent inclined reinforcing ribs two (17) are symmetrically arranged.

5. A battery box according to claim 1, characterized in that, The height of the annular step is lower than the thickness of the gasket (7).

6. A battery box according to claim 1, characterized in that The box body bottom plate (5) is formed by aluminum extrusion. The internal cavity structure takes into account the cold plate flow channel to dissipate heat from one narrow side of the blade cell. A stamping liquid cooling plate formed by stamping aluminum brazing process is correspondingly provided on the other narrow side of the blade cell. The flow ports (15) of the cold plate flow channel and the stamping liquid cooling plate are both in an S-shaped structure and adopt a form of inlet from both sides and outlet in the middle.

7. A battery box according to claim 1, characterized in that, The inner surface of the box body bottom plate (5) is sprayed with a heat-insulating material (2), and the thickness of the heat-insulating material (2) is greater than 1 mm.

8. A battery box according to claim 7, characterized in that, An insulating powder (4) is sprayed on the surface of the heat-insulating material (2), and the thickness of the insulating powder (4) is greater than 60 μm.

9. A battery pack, characterized in that, It includes the battery box body according to any one of claims 1 - 8 and the battery module in the battery box body.

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