Upper cover of battery box
By using thermoplastic composite materials to design hollow or solid strip reinforcement ribs in the battery box cover and setting internal and external thickening blocks, the problems of fiber breakage and stress concentration are solved, and the lightweight and high-strength battery box cover manufacturing is achieved.
Patent Information
- Application Number
- CN202422197569.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-09
- Publication Date
- 2025-09-16
- Estimated Expiration
- 2034-09-09
AI Technical Summary
During the manufacturing process, existing thermoplastic composite battery box covers suffer fiber breakage and stress concentration, leading to rupture, making them unable to meet high-pressure test requirements and increasing product weight and cost.
The battery box cover is made of thermoplastic composite materials and is designed with hollow or solid strip reinforcement ribs distributed in the middle to avoid contact with the junction edges. Internal and external thickening blocks are set in the flat plate area to enhance strength, and a non-edge design is adopted to reduce stress concentration.
It effectively avoids stress concentration and rupture of the battery box cover during the molding process, improves the air pressure resistance, reduces material cost and weight, and meets the requirements of high pressure testing.
Smart Images
Figure CN223347934U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of battery boxes, in particular to a battery box upper cover. Background Art
[0002] Metal battery cases conduct heat quickly and are easily affected by external temperatures, causing the battery to waste significant energy in temperature regulation (the thermal conductivity of an aluminum alloy battery case is 237W / mK). This can lead to a 50% reduction in battery life in winter and a 30% reduction in summer. Composite battery cases conduct heat more slowly (with a thermal conductivity of 0.23W / mK). These are not only lighter but also provide scientific and effective protection against external heat and cold, effectively maintaining the battery's operating temperature and preventing battery drain.
[0003] Currently, the ends of the reinforcing ribs on the top cover of a thermoset composite battery case connect to the intersection of the vertical surfaces. The ribs extend from the large surface to the intersection of the vertical surfaces. The fibers are crushed by the mold at the sudden corners, causing local stresses to exceed the yield strength limit, causing local cracks in the top cover and compromising the strength of the battery case. Multiple mold surfaces simultaneously press down on the fibers at the intersection of the large surface and the vertical surfaces, applying pressure simultaneously. The fibers are squeezed, pulled, and severed at the corners, creating defects where stress is concentrated. Thermoset PCM composites can be locally cut, stacked, and preformed into the mold to avoid fiber crushing. Thermoset PCM prepreg is softened and can be preformed in the mold, especially at the corners.
[0004] The battery box of new energy vehicles made of "thermoplastic continuous fiber composite materials" has three major manufacturing challenges:
[0005] 1) Fiber breakage: Thermoplastic continuous fiber sheet is a solidified sheet that cannot be pre-layered and stacked. Simultaneous molding on multiple mold surfaces will inevitably cause fiber breakage due to the ribs. Thermoplastic continuous fiber sheet cannot be pre-molded in the mold and must be extruded. This cannot prevent fiber breakage, and simultaneous compression of the fibers on multiple surfaces is essential.
[0006] 2) Mechanical stress concentration: The reinforcement ribs extend from the large surface to the junction edge of the vertical surface. Due to the balloon effect, stress concentration occurs at the end of the reinforcement ribs, which exceeds the yield strength limit of the material, causing rupture and damage to the battery box.
[0007] 3) Mechanical stress concentration: The large surface stress extends to the vertical surface, and the balloon effect causes stress concentration on the corner / vertical surface, which exceeds the yield strength limit of the material and causes rupture of the vertical surface.
[0008] like Figure 1Figure (1) shows the current design of hollow reinforcing ribs for the upper cover of a composite battery box. "Face-to-edge" means that the body or end of the reinforcing rib touches the boundary edge, which is the boundary edge between the large surface and the vertical surface of the battery box. The hollow reinforcing rib extends from the large surface to the vertical surface, and the end of the reinforcing rib touches the boundary edge. The fiber will be crushed and broken at the sudden change corner, causing the strength of the battery box to be damaged. At the junction of the large surface and the vertical surface, multiple mold surfaces press down on the fiber at the same time. The fiber is squeezed, pulled, and cut at the corner, causing a stress concentration crack. In the blowing test, the middle of the large surface bulged to a height of 5 cm. The material near the corner was subjected to the tensile force generated by the surrounding elastic deformation. The stress concentration was as high as 390 MPa, which suddenly exceeded the material yield strength limit of 220 MPa, and continued to break. Corners are also prone to stress concentration in structural mechanics and are prone to forming cracks. Figure 1 Figure (2) shows the current design of a composite battery box cover without any reinforcement ribs. Without any reinforcement ribs on the large surface, the maximum stress in the blowing test was concentrated in the middle of the long side and the middle of the wide side. The large surface bulged to a height of 15cm, with a maximum stress of 253MPa, exceeding the material's yield strength of 220MPa, and cracking occurred prematurely at 14°C under 3.5KPa pressure. To meet the 10KPa compressive strength requirement, the cover without any reinforcement ribs relies on increasing the material thickness to increase strength. However, the increase in material weight and cost increases the product, which is not a good strategy.
[0009] This technical solution reflects two problems of the current composite material battery box cover:
[0010] 1) Multi-mode surfaces can cause stress concentration;
[0011] 2) The "edge" reinforcement ribs produce stress concentration and cause rupture.
[0012] The product must meet the compressive strength requirements of GB / T31467, satisfy airtightness standards, and be lightweight. The above examples demonstrate the necessity of reinforcing ribs, and even more importantly, how they are arranged. Thermoset composites can be preformed and layered before being molded to avoid fiber breakage. Thermoplastic continuous fiberboard cannot be pre-layered, and simultaneous compression from multiple mold surfaces inevitably results in fiber breakage. Batteries in new energy vehicles release gases, causing the battery case to bulge. Each battery case must withstand a 10kPa high-pressure air blow test. When the upper cover is subjected to high pressure, the center bulges into a hemispherical shape. At this point, stress concentrations occur at the corners, exceeding the material's yield strength, leading to rupture at 3.5kPa (before reaching 10kPa). The hollow reinforcing ribs "touching the edge" result in a production yield of only 10% for thermoplastic continuous fiber battery cases. Utility Model Content
[0013] The purpose of the utility model is to provide a battery box cover to solve the problems mentioned in the background technology.
[0014] In order to achieve the above purpose, the present invention provides the following technical solutions:
[0015] A battery box cover is made of a thermoplastic composite material and includes a panel, side panels, and flange plates that are connected in sequence from the inside out and formed integrally; a junction edge is formed between the panel and the side panels; a reinforcing rib area is provided in the middle of the panel, and the periphery of the corresponding reinforcing rib area is a flat plate area; a plurality of reinforcing ribs are provided on the reinforcing rib area; and the reinforcing rib area does not contact the junction edge.
[0016] Further description of the present invention: the reinforcing ribs are hollow strip-shaped reinforcing ribs and are distributed in parallel in the front and back of the reinforcing rib area.
[0017] Further description of the present invention: the reinforcing ribs include hollow strip reinforcing ribs and solid strip reinforcing ribs; at least one solid strip reinforcing rib is provided and distributed in the middle position of the reinforcing rib area in the front-to-back direction; the hollow strip reinforcing ribs are distributed on the front and back sides of the solid strip reinforcing ribs.
[0018] Further description of the present invention: the inner and outer sides of the flat plate area, side plates and flange plates are respectively provided with inner thickening blocks and outer thickening blocks; the inner and outer thickening blocks are both thermoplastic composite materials and are integrally formed on the flat plate area, side plates and flange plates.
[0019] To further describe the present invention, the inner thickening block is a thermoplastic homopolymer fiber-reinforced composite material; and the outer thickening block is a thermoplastic copolymer-modified polymer composite material.
[0020] Further description of the present invention: the distance between the edge of the reinforcing rib area and the junction edge in the length direction is D1, and the distance between the edge of the reinforcing rib area and the junction edge in the width direction is D2; the distance D1 is 0.5mm-1000mm; the distance D2 is 0.5mm-750mm.
[0021] A battery box cover is made of a thermoplastic composite material and includes a panel; the panel includes a reinforcing rib area located in the middle and a flat plate area located on the periphery of the reinforcing rib area; the reinforcing rib area does not contact the edge of the panel; the reinforcing rib area is provided with a plurality of reinforcing ribs; an inner thickening block and an outer thickening block are respectively provided on the inner and outer sides of the peripheral edge of the flat plate area; the inner and outer thickening blocks are both made of thermoplastic composite materials and are integrally formed on the flat plate area.
[0022] To further describe the present invention, the inner thickening block is a thermoplastic homopolymer fiber-reinforced composite material; and the outer thickening block is a thermoplastic copolymer-modified polymer composite material.
[0023] The beneficial effects of the utility model are:
[0024] This design uses thermoplastic composite materials to make the battery box cover, which is easy to manufacture, light weight, good thermal insulation effect, low manufacturing cost and high strength. The reinforcing ribs are formed in the reinforcing rib area in the middle of the panel. The reinforcing ribs do not contact the edge of the panel, which can effectively solve the defect of stress concentration at the corner position during the molding process, causing cracks. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is a structural diagram of the battery box upper cover of the prior art of the utility model;
[0026] Figure 2 This is a schematic diagram of the regional distribution structure of the utility model;
[0027] Figure 3 This is a structural diagram of Example 1 of the present utility model;
[0028] Figure 4 This is a stress position distribution diagram of Example 1 of the present utility model;
[0029] Figure 5 This is a structural diagram of Example 2 of the present utility model;
[0030] Figure 6 yes Figure 5 Cross-sectional view of EE;
[0031] Figure 7 This is a balloon effect diagram;
[0032] Figure 8 This is a schematic diagram of the air blowing test method for the battery box upper cover of the utility model;
[0033] Figure 9 This is a structural diagram of Example 3 of the present utility model;
[0034] Figure 10 yes Figure 9 Cross-sectional view of middle GG;
[0035] Figure 11 yes Figure 10 A partial enlarged view of middle A;
[0036] Figure 12 This is a structural diagram of Example 4 of the present utility model;
[0037] Figure 13 yes Figure 12 Cross-sectional view of middle HH;
[0038] Figure 14 This is a structural diagram of other reinforcing rib forms of the utility model. DETAILED DESCRIPTION
[0039] The present invention will be further described below with reference to the accompanying drawings:
[0040] Example 1: Figure 2-4 As shown, a battery box cover is made of thermoplastic composite material, including a panel 1, a side panel 2 and a flange plate 3 that are connected in sequence from the inside to the outside and formed as one piece; a junction edge 01 is formed between the panel 1 and the side panel 2; a reinforcing rib area 11 is provided in the middle of the panel 1, and the outer periphery of the corresponding reinforcing rib area 11 is a flat plate area 12; a plurality of reinforcing ribs 101 are provided on the reinforcing rib area 11; the reinforcing rib area 11 does not contact the junction edge 01; the reinforcing ribs 101 are hollow strip-shaped reinforcing ribs 1011 and are distributed in parallel in the front and back of the reinforcing rib area 11.
[0041] The distance between the edge of the reinforcing rib area 11 and the junction edge 01 in the length direction is D1, and the distance between the edge of the reinforcing rib area 11 and the junction edge 01 in the width direction is D2; the distance D1 is 0.5mm-1000mm; the distance D2 is 0.5mm-750mm, and D1 and D2 are generally set at about 100mm.
[0042] In order to overcome the 390MPa stress concentration problem in the existing technology, this design adopts a "non-edge" hollow reinforcement rib 101 design. The stress p is concentrated in the middle position of the flat plate area 12 of the panel 1 in the length direction and the middle position in the width direction. The stress value is 140-150MPa, which is within the safe range of the material yield strength of 220MPa, thereby effectively avoiding damage to the product.
[0043] Example 2: Figure 5-6 As shown, the difference from Example 1 is that the reinforcement rib 101 includes a hollow strip reinforcement rib 1011 and a solid strip reinforcement rib 1012; at least one solid strip reinforcement rib 1012 is provided and distributed in the middle position of the reinforcement rib area 11 in the front-to-back direction; the hollow strip reinforcement rib 1011 is distributed on the front and back sides of the solid strip reinforcement rib 1012. The provision of the solid strip reinforcement rib 1012 can greatly increase the air pressure resistance, while the material and cost will increase accordingly. Therefore, a certain number of solid strip reinforcement ribs 1012 can be added according to actual needs.
[0044] like Figure 7As shown, the balloon effect: Two balloons are inflated together. Ball 100 has a thinner surface, while ball 200 has a thicker surface due to the addition of a solid reinforcement rib 201. Air is blown into both balloons through the nozzle. Ball 100 easily inflates into a large, round ball. Ball 200, on the other hand, inflates into a spherical shape. However, the volume of ball 200 is smaller than that of ball 100 because the solid reinforcement rib 201 reduces the inflated surface area of ball 200. The air pressure exerts a smaller force F (F = PA) on a smaller surface area. The solid reinforcement rib 201 increases the strength of ball 200, resulting in a smaller inflated volume at the same air pressure.
[0045] like Figure 8 As shown, the battery box cover is blown with 10KPa test method: fix the flange plate 3 on the platform, open the air valve under the platform to inflate, the middle part of the cover gradually bulges, and is bulged into a hemispherical shape by the high air pressure. Figure (1) is the state before the cover is blown, and Figure (2) is the state before the cover is blown. Figure 4 The blowing state of adding hollow bar reinforcement ribs 1011, and Figure (3) shows the blowing state of adding solid bar reinforcement ribs 1012.
[0046] 10kPa high-pressure air P is introduced into the battery box cover through the air nozzle. The cover, which has a uniform thickness and a hollow bar reinforcement 1011 design, is easily blown into an arc shape with a bulging height H of 800mm. The air pressure exerts a large tensile force on a large area, and the maximum stress in the stress domain is 147MPa.
[0047] By adding a single solid reinforcing rib 1012 in the center, the upper cover is inflated into an arc shape, with the maximum stress in the stress domain reaching 126 MPa, a 14% reduction. This is because the solid reinforcing rib 1012 reduces the bulge height h to 744 mm (a 7% reduction in bulge height). Adding a single solid reinforcing rib 1012 reduces the bulge area, and air pressure exerts a small tensile force on a small area. Adding multiple solid reinforcing ribs 1012 significantly reduces the bulge area, significantly reducing the tensile force, and thus the stress in the stress domain.
[0048] Example 3: Figure 9-11 As shown, the difference from Example 1 is that the inner and outer sides of the flat plate area 12, the side plate 2 and the flange plate 3 are respectively provided with an inner thickening block 4 and an outer thickening block 5; the inner and outer thickening blocks 4 and 5 are both thermoplastic composite materials and are integrally formed on the flat plate area 12, the side plate 2 and the flange plate 3 to enhance strength and prevent cracking, wherein the outer thickening block 5 is made of a modified polymer of thermoplastic "copolymer" PP polypropylene, and the inner thickening block 4 is made of a fiber-reinforced composite material of thermoplastic "homopolymer" PP polypropylene polymer. Inner thickening block 4 Used to enhance pull strength, External thickening block 5 is used for avoid outside side risers Skin cracking.
[0049] Example 4: Figure 12-13 As shown, a battery box cover is made of thermoplastic composite material, including a panel 1; the panel 1 includes a reinforcing rib area 11 located in the middle and a flat plate area 12 located on the periphery of the reinforcing rib area 11; the reinforcing rib area 11 does not contact the edge of the panel 1; a plurality of reinforcing ribs 101 are provided on the reinforcing rib area 11, and an inner thickening block 4 and an outer thickening block 5 are respectively provided on the inner and outer sides of the peripheral edge position of the flat plate area 12; the inner thickening block 4 and the outer thickening block 5 are both thermoplastic composite materials and are integrally formed on the flat plate area 12. Specifically, the outer thickening block 5 is made of a modified polymer of thermoplastic "copolymer" PP polypropylene, and the inner thickening block 4 is made of a fiber-reinforced composite material of thermoplastic "homopolymer" PP polypropylene polymer. Inner thickening block 4 Used to enhance pull strength, External thickening block 5 is used for avoid Side panel skin Cracking; The upper cover disclosed in this embodiment has no side panels and flange panels. Although there is only a panel 1, a bending angle will be generated near the edge during the blow molding process, causing a stress of 250 MPa exceeding the yield strength. Therefore, it is necessary to form the reinforcing rib 101 in the reinforcing rib area 11 in the middle position, and set an outer thickening block 5 and an inner thickening block 4 at the outer edge position for reinforcement to avoid stress concentration and damage to the product.
[0050] In addition, if Figure 14 As shown, the reinforcing ribs 101 can also be arranged in a longitudinal direction, staggered in both horizontal and vertical directions, or in a cross or other geometric shape according to actual needs.
[0051] The above description does not limit the technical scope of the present invention. Any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A battery box cover made of thermoplastic composite material, characterized by: It includes a panel, a side panel and a flange plate that are connected in sequence from the inside to the outside and formed as one piece; a junction edge is formed between the panel and the side panel; a reinforcing rib area is provided in the middle of the panel, and the periphery of the corresponding reinforcing rib area is a flat plate area; a plurality of reinforcing ribs are provided on the reinforcing rib area; the reinforcing rib area does not contact the junction edge.
2. The battery box cover according to claim 1, characterized in that: The reinforcing ribs are hollow strip-shaped reinforcing ribs and are distributed in parallel in the front and back of the reinforcing rib area.
3. The battery box cover according to claim 1, characterized in that: The reinforcing ribs include hollow strip reinforcing ribs and solid strip reinforcing ribs; at least one solid strip reinforcing rib is provided and distributed in the middle position of the reinforcing rib area in the front-to-back direction; the hollow strip reinforcing ribs are distributed on both sides of the front and back of the solid strip reinforcing ribs.
4. The battery box cover according to claim 1, characterized in that: The inner and outer sides of the flat plate area, side plates and flange plates are respectively provided with inner thickening blocks and outer thickening blocks; the inner and outer thickening blocks are both made of thermoplastic composite materials and are integrally formed on the flat plate area, side plates and flange plates.
5. The battery box cover according to claim 4, characterized in that: The inner thickening block is a thermoplastic homopolymer fiber-reinforced composite material; the outer thickening block is a thermoplastic copolymer-modified polymer composite material.
6. The battery box cover according to claim 1, characterized in that: The distance between the edge of the reinforcing rib area and the boundary edge in the length direction is D1, and the distance between the edge of the reinforcing rib area and the boundary edge in the width direction is D2; the distance D1 is 0.5mm-1000mm; the distance D2 is 0.5mm-750mm.
7. A battery box cover made of thermoplastic composite material, characterized by: The panel comprises a reinforcing rib area located in the middle and a flat plate area located on the periphery of the reinforcing rib area; the reinforcing rib area does not contact the edge of the panel; the reinforcing rib area is provided with a plurality of reinforcing ribs; an inner thickening block and an outer thickening block are respectively provided on the inner and outer sides of the peripheral edge position of the flat plate area; the inner thickening block and the outer thickening block are both made of thermoplastic composite materials and are integrally formed on the flat plate area.
8. The battery box cover according to claim 7, characterized in that: The inner thickening block is a thermoplastic homopolymer fiber-reinforced composite material; the outer thickening block is a thermoplastic copolymer-modified polymer composite material.