Battery pack housing

Abstract

A battery pack housing (1). The battery pack housing (1) comprises: a cover body (10) having a pressure relief hole (13); and an explosion-proof valve assembly (20) disposed on the cover body (10), wherein the explosion-proof valve assembly (20) comprises a valve body (21) and a diaphragm (22) connected to each other, the valve body (21) is connected to the cover body (10) such that the diaphragm (22) seals the pressure relief hole (13), and the valve body (21) and the cover body (10) are laser-welded to each other.

Description

A battery pack housing

[0001] This application claims priority to Chinese Patent Application No. 202421724738.8, filed on July 19, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to a battery pack housing. Background Technology

[0003] Safety is one of the most important technical indicators of a battery. To ensure the safety of power batteries, explosion-proof vent valves are typically installed on the battery to release internal pressure. Specifically, the explosion-proof vent valve is located on the top cover or casing. When the internal pressure of the battery exceeds a safe level, the gas inside the battery will rupture the explosion-proof vent, releasing the internal pressure in time and preventing the battery from exploding due to excessive internal pressure. Explosion-proof vent valves are widely used in the automotive industry, especially in power batteries. Any battery pack requires one or even multiple explosion-proof vent valves to ensure pressure relief and balance within the battery pack. Invention Overview

[0004] Following the trend towards lightweight vehicles, more and more battery pack designs are using plastic housings. However, the valve body is typically designed using PC or PA66 as the main material, and then integrated onto the battery pack via bolts, clips, or sealing rings. Another approach is to injection mold the valve body onto the plastic cover. However, both of these solutions make it difficult to guarantee the flatness of the explosion-proof membrane during welding, thus slowing down the overall product development process.

[0005] Therefore, there is an urgent need to design a battery pack casing to address the technical risks.

[0006] This application provides a battery pack housing, which includes: a cover having a pressure relief hole; and an explosion-proof valve assembly disposed on the cover, the explosion-proof valve assembly including a valve body and a diaphragm connected to each other, the valve body being connected to the cover so that the diaphragm blocks the pressure relief hole; wherein the valve body and the cover are laser welded together. Beneficial effects

[0007] The battery pack housing provided in this application has a pressure relief hole through the cover, and a diaphragm is correspondingly provided with the pressure relief hole. In this way, when the gas pressure inside the battery exceeds the safe value, the gas inside the battery will break through the diaphragm and release the gas pressure inside the battery in time, thereby preventing the battery from exploding due to excessive gas pressure. Furthermore, the valve body and the cover are laser welded, so there is no need for additional fasteners, sealing rings and other materials, which can reduce production costs to a certain extent. At the same time, it can also prevent deformation of the explosion-proof valve assembly. Moreover, laser welding has lower requirements for processing precision, thereby improving the production efficiency of the battery pack housing and thus accelerating the product development progress. Attached Figure Description

[0008] Figure 1 is a perspective view of the battery pack housing provided in the embodiment;

[0009] Figure 2 is a top view of the battery pack housing provided in the embodiment;

[0010] Figure 3 is a cross-sectional view of section AA in Figure 2;

[0011] Figure 4 is an enlarged view of point B in Figure 3;

[0012] Figure 5 is a perspective view of the cover provided in the embodiment;

[0013] Figure 6 is a perspective view of the valve body provided in the embodiment;

[0014] Figure 7 is a perspective view of the valve body provided in the embodiment;

[0015] Explanation of reference numerals in the attached figures:

[0016] 1. Battery pack casing; 10. Cover; 11. Outer surface; 12. Inner surface; 13. Pressure relief hole;

[0017] 20. Explosion-proof valve assembly; 21. Valve body; 211. Through hole; 212. First positioning groove; 213. Second positioning groove; 214. Connecting part; 215. Mounting part; 22. Diaphragm;

[0018] 30. First protrusion;

[0019] 40. Second protrusion. Embodiments of the present invention

[0020] As shown in Figures 1 to 7, an embodiment of the present invention provides a battery pack housing, which includes: a cover 10 having a pressure relief hole 13; and an explosion-proof valve assembly 20 disposed on the cover 10. The explosion-proof valve assembly 20 includes a valve body 21 and a diaphragm 22 connected to each other. The valve body 21 is connected to the cover 10 so that the diaphragm 22 blocks the pressure relief hole 13. The connecting part 214 is laser welded to the cover 10.

[0021] By applying the technical solution of this utility model, a pressure relief hole 13 is provided through the cover 10, and a diaphragm 22 is correspondingly provided with the pressure relief hole 13. In this way, when the gas pressure inside the battery exceeds the safe value, the gas inside the battery will break through the diaphragm 22 to release the gas pressure inside the battery in time, thereby avoiding the battery explosion caused by excessive gas pressure inside the battery. Furthermore, the valve body 21 and the cover 10 are laser welded, so there is no need for additional fasteners, sealing rings and other materials, which can reduce production costs to a certain extent. At the same time, it can also prevent the deformation of the explosion-proof valve assembly 20. Moreover, laser welding has lower requirements for processing precision, thereby improving the production efficiency of the battery pack shell and thus accelerating the product development progress.

[0022] In this application, the cover 10 has an outer surface 11 and an inner surface 12 disposed opposite to each other, and a pressure relief hole 13 extends from the inner surface 12 to the outer surface 11 and is disposed through it.

[0023] In this application, due to the extremely high energy density of the laser beam in laser welding, the materials to be welded can be rapidly heated and melted, thus achieving high-speed and high-efficiency welding. This efficiency not only improves production efficiency but also reduces energy consumption. Simultaneously, the heating area in laser welding is very small, resulting in a shallow penetration depth. A shallow penetration depth means a relatively small volume of material is heated and melted during the welding process, which helps reduce thermal stress and thermal deformation in the welding area and surrounding materials. Furthermore, laser welding allows for precise control of the laser beam's energy and focus point, thereby achieving precise control of the penetration depth, making the welding process more controllable and contributing to improved quality and consistency of the battery cover 10. Moreover, laser welding offers high welding speed and a small heat-affected zone, thereby reducing deformation during the welding process.

[0024] Furthermore, laser welding produces welds with good morphology, stable dimensions, and fewer defects, such as porosity and cracks. This enables high-precision, high-quality welding of the cover 10 and the explosion-proof valve assembly 20, which helps improve the overall performance and service life of the battery pack casing. Laser welding can also weld a variety of materials, including metals, plastics, ceramics, and high-melting-point, brittle refractory materials. This increases the flexibility in material selection for the battery pack casing, allowing for selection based on different usage environments to meet user needs.

[0025] Specifically, laser welding eliminates the need for contact between the welding head and the workpiece, as well as the need for electrodes or filler materials, reducing pollution and waste. Furthermore, laser welding can be transmitted and transformed using optical elements, easily integrating with automated equipment such as robots to achieve automated and multi-station processing, thus adapting to various complex welding tasks. Laser welding also produces no harmful gases or noise, posing no risk to humans or the environment. Simultaneously, the absence of mechanical contact during laser welding reduces safety hazards associated with such contact. The laser beam can be focused to high power density, achieving a high weld depth-to-width ratio, up to 10:1. This gives laser welding a significant advantage in applications requiring deep penetration welding. Moreover, laser welding allows for precise control of the welding process, achieving accurate welding. The laser has no inertia and can start and stop rapidly, making it advantageous in applications requiring frequent start-stop operations or precise control. Furthermore, the laser welding process is easy to control; different welding effects can be achieved by adjusting laser parameters.

[0026] In one embodiment, the valve body 21 includes a connecting portion 214 and a mounting portion 215. The connecting portion 214 is connected to the cover 10, and the mounting portion 215 has a through hole 211 that communicates with the pressure relief hole 13. The diaphragm 22 is connected to the mounting portion 215 and seals the through hole 211. With this configuration, when the internal pressure of the battery exceeds a safe value, the gas inside the battery will rupture the diaphragm 22 to release the internal pressure in a timely manner, thereby preventing the battery from exploding due to excessive internal pressure and maintaining the safety of the battery during use.

[0027] In this application, membrane 22 is specifically a breathable membrane made of a waterproof and dustproof material, such as microporous polytetrafluoroethylene (PTFE). PTFE breathable membranes are widely used in the waterproof and breathable field due to their unique properties. The micropore size on the surface of the PTFE breathable membrane is designed to be much larger than gas molecules in the air, but much smaller than the particle size of water, dust, and other particulate matter, thus achieving excellent waterproof and breathable effects. Depending on the manufacturing process, PTFE waterproof and breathable membranes can be divided into two types: stretched PTFE (ePTFE) and sintered PTFE. Stretched waterproof and breathable membranes are made from a PTFE base film through unidirectional or multidirectional stretching, possessing strong toughness and being less prone to breakage. They are suitable for scenarios with relatively mild temperature differences, requiring pressure balance, and without explosion risks. Sintered waterproof and breathable membranes, on the other hand, are made from a PTFE substrate through a sintering process. They are relatively brittle and easily punctured, suitable for scenarios with severe temperature rises or explosion risks, requiring the membrane to "self-explode" to rapidly release pressure. Application Scenarios: The selection of explosion-proof venting membranes is particularly important in the battery packs of new energy vehicles. Because battery packs need to maintain internal and external pressure balance during normal operation to reduce condensation and other problems, and also need to rapidly release internal pressure to avoid catastrophic consequences in the event of thermal runaway or other abnormal situations, sintered waterproof venting membranes are preferred for power batteries. These membranes can quickly "self-explode" to release pressure when the internal pressure of the battery pack becomes too high, thus providing an explosion-proof function.

[0028] Meanwhile, the breathable membrane made of polytetrafluoroethylene is lightweight, durable, waterproof, windproof, dustproof, and breathable. Air molecules can pass through, but water molecules cannot. This effectively prevents the electrolyte inside the battery module from entering the pressure relief, avoiding the risk of leakage and further ensuring the safety and reliability of the battery module during use.

[0029] Of course, other materials can be used for the diaphragm 22, as long as they can meet the requirements of the device.

[0030] Specifically, in this application, the pressure relief hole 13 adopts a pinless design. This increases the cross-sectional area of ​​the pressure relief hole 13 under VDA NW14 conditions, allowing for faster pressure relief and effectively preventing thermal runaway of the battery module. Furthermore, the pinless design simplifies mold design and facilitates molding. Additionally, the pinless design avoids pressure changes in the battery pack caused by high altitudes, extreme temperature fluctuations, etc., which could lead to membrane deformation and accidental contact with the pins, resulting in airtight failure of the diaphragm 22.

[0031] Furthermore, the pressure relief port 13 with its pinless design can automatically open and release pressure when the internal pressure of the battery pack reaches the preset burst point, without relying on mechanical components such as springs or pins. This ensures the accuracy and stability of the burst point. Because it does not rely on complex mechanical structures, the pressure relief port 13 with its pinless design typically has a faster response speed. This means that when the internal pressure of the battery pack abnormally increases, the explosion-proof valve can activate and release pressure more quickly, thus more effectively protecting the equipment. This automatic bursting mechanism can rapidly reduce internal pressure, preventing battery pack damage or safety accidents caused by excessive pressure, protecting the battery pack from damage, and ensuring the long-term stable operation of the battery pack. The pressure relief port 13 with its pinless design typically has excellent air permeability and waterproof performance, effectively preventing external moisture and impurities from entering the battery pack while ensuring gas flow inside. This helps reduce the humidity and temperature inside the battery pack, improving the operating efficiency and stability of the battery pack.

[0032] In one embodiment, the connecting portion 214 includes a connecting surface, and the mounting portion 215 includes a mounting surface, with the connecting surface and the mounting surface located on opposite sides of the valve body 21, respectively. This arrangement facilitates the installation of the diaphragm 22 to the valve body 21 and the valve body 21 to the cover 10, thereby improving the installation efficiency between components.

[0033] In one embodiment, the valve body 21 includes a first positioning groove 212, the bottom of which has a mounting surface, and the diaphragm 22 is disposed within the first positioning groove 212. This arrangement utilizes the positioning groove 212 to position and install the diaphragm 22, thereby further improving the installation efficiency between the diaphragm 22 and the valve body 21, which is beneficial for increasing production efficiency.

[0034] In one embodiment, the diaphragm 22 is welded to the mounting portion 215. In this application, the diaphragm 22 and the mounting portion 215 are ultrasonically welded. Ultrasonic welding converts a 50 / 60 Hz current into high-frequency electrical energy (typically 15, 20, 30, or 40 kHz) using an ultrasonic generator. The converted high-frequency electrical energy is then converted again into mechanical motion of the same frequency by a transducer. This mechanical motion is then transmitted to the welding head via an amplitude converter. The welding head transmits the received vibrational energy to the joint of the workpiece to be welded. In this area, the vibrational energy is converted into heat energy through friction, melting materials such as plastics. After the ultrasonic waves stop, a certain pressure is maintained to allow the welded part to cool and solidify, thus achieving the welding purpose. Therefore, ultrasonic welding is fast, completing the welding process in a short time and improving the production efficiency of the battery pack casing. Simultaneously, ultrasonic welding provides high weld strength and good sealing performance, enabling the battery pack casing to have excellent sealing performance to meet user requirements.

[0035] Furthermore, ultrasonic welding requires no additional welding materials, produces no harmful substances, and is environmentally friendly. It is also applicable to a wide range of materials, including thermoplastics, metals (such as thin pieces of gold, silver, copper, and aluminum), fabrics, and films, thus broadening its applicability. Simultaneously, compared to traditional welding processes, ultrasonic welding reduces production costs, facilitating the mass production of battery pack casings.

[0036] Specifically, the valve body 21 also includes a second positioning groove 213, the bottom of which has a connecting surface. A first protrusion 30 is also provided on the inner surface 12 of the cover 10, and the first protrusion 30 is arranged circumferentially around the pressure relief hole 13. The bottom of the second positioning groove 213 is connected to the first protrusion 30. This arrangement facilitates welding of the valve body 21 and the cover 10, thereby improving the welding efficiency between them.

[0037] In this application, the first protrusion 30 is a continuous structure and is integrally formed with the cover 10. This integral forming structure, achieved through a single molding process, makes the overall structure of the battery pack casing more robust and secure. This structural approach avoids the seam problems that may arise from traditional multi-part assembly, thereby improving the overall strength and stability of the battery pack casing. Furthermore, integral molding technology typically enables high-precision, high-quality production of battery pack casings. Whether through injection molding, die casting, or other molding methods, integral molding technology ensures the dimensional and shape accuracy of the battery pack casing, meeting the demands of precision manufacturing.

[0038] Furthermore, unibody construction reduces the number of parts and assembly steps, thereby lowering production costs. In addition, by optimizing design and production processes, unibody technology can further reduce material waste and energy consumption, improving production efficiency. Unibody construction can complete the battery pack casing manufacturing process in a short time, increasing production efficiency. This is particularly important for mass production, significantly shortening production cycles and meeting market demands for rapid delivery. At the same time, unibody structures generally have better durability. Due to their robust and seamless structure, battery pack casings are less prone to loosening or breakage during use, thus extending their lifespan.

[0039] Optionally, in other embodiments of this application, the first protrusion 30 may also be configured as a discontinuous structure. The specific configuration should be selected according to the usage environment of the battery pack housing, so as to improve the applicability and scope of application of the battery pack housing.

[0040] In one embodiment, a second protrusion 40 is further provided on the inner surface 12 of the cover 10. The second protrusion 40 is arranged circumferentially around the first protrusion 30, and there is a gap between the second protrusion 40 and the first protrusion 30. This arrangement facilitates the insertion of the gripper of the automated robot into the gap to assemble and weld the valve body 21 and the cover 10, thereby further improving the welding efficiency of the valve body 21 and the cover 10. In this application, the second protrusion 40 is a continuous structure and is integrally formed with the cover 10. The integrally formed structure makes the overall structure of the battery pack housing more robust and solid through one-time molding.

[0041] Optionally, in other embodiments of this application, the second protrusion 40 may also be configured as a discontinuous structure. The specific configuration should be selected according to the usage environment of the battery pack housing, so as to improve the applicability and scope of application of the battery pack housing.

[0042] In one embodiment, the height of the first protrusion 30 protruding from the inner surface 12 is less than or equal to the height of the second protrusion 40 protruding from the inner surface 12. This arrangement facilitates limiting the valve body 21 during installation to prevent displacement of the valve body 21.

[0043] In one embodiment, the mounting portion 215 and the cover 10 are made of the same material. Since the same material is laser welded together, they are easier to fuse, thereby further improving the welding efficiency of the two and making the welding process simpler, thus maximizing the production efficiency of the battery pack casing.

[0044] Specifically, the materials of the mounting part 215 and / or the cover 10 include nylon. In this application, the valve body 21 is made of a light-transmitting material (i.e., black PA66+GF with 30% light transmittance), while the cover 10 is made of light-absorbing PA66+30GF (i.e., black nylon that does not require special treatment). Since the mechanical properties of PA66+GF (i.e., polyamide 66 plus glass fiber composite material) are significantly improved, its strength is much higher than that of ordinary plastic materials. Its tensile strength can reach more than 100MPa. At the same time, the material has high stiffness and an elastic modulus of more than 5000MPa. It has excellent resistance to bending, compression and torsion, thereby ensuring the structural strength of the valve body 21.

[0045] Furthermore, PA66+GF exhibits excellent heat resistance, allowing it to operate in high-temperature environments. Its heat distortion temperature can reach over 200℃, and it is not easily deformed, cracked, or embrittled, demonstrating excellent durability. This gives the valve body 21 a significant advantage in high-temperature operating environments. Since PA66 itself has good chemical corrosion resistance, the addition of glass fiber further enhances its corrosion resistance. PA66+GF material is not easily corroded by chemicals and can resist corrosion from many chemicals, making the valve body 21 perform excellently in applications requiring corrosion resistance. Moreover, the PA66+GF composite material has good injection molding and extrusion processing properties, facilitating the manufacture of valve bodies 21 in different shapes, thus meeting the processing requirements of various environments.

[0046] In this application, the pressure relief hole 13 has a circular cross-section. The circular structure provides the most uniform stress distribution, making the pressure relief hole 13 more stable and reliable under stress, thus reducing the risk of deformation and damage. Simultaneously, the circular structure provides a tighter interface fit, reducing the possibility of leakage and improving the sealing performance of the battery pack casing. Furthermore, the circular structure provides the smoothest flow path; this continuous and smooth shape helps reduce fluid resistance and eddy current generation within the pressure relief hole 13, thereby improving fluid transport efficiency and maximizing the pressure relief efficiency of the battery pack casing.

[0047] Of course, in other embodiments of this application, the cross-section of the pressure relief hole 13 can also be set to square or trapezoidal, as long as it can meet the pressure relief requirements of the battery pack housing. The specific setting should be selected according to the usage environment of the battery pack housing, and no specific restrictions are made here.

[0048] By applying the technical solution of this utility model, a pressure relief hole 13 is provided through the cover 10, and a diaphragm 22 is correspondingly provided with the pressure relief hole 13. In this way, when the gas pressure inside the battery exceeds the safe value, the gas inside the battery will break through the diaphragm 22 to release the gas pressure inside the battery in time, thereby avoiding the battery explosion caused by excessive gas pressure inside the battery. Furthermore, the valve body 21 and the cover 10 are laser welded, so there is no need for additional fasteners, sealing rings and other materials, which can reduce production costs to a certain extent. At the same time, it can also prevent the deformation of the explosion-proof valve assembly 20. Moreover, laser welding has lower requirements for processing precision, thereby improving the production efficiency of the battery pack shell and thus accelerating the product development progress.

Claims

1. A battery pack housing, comprising: a cover body having a pressure relief hole; an explosion-proof valve assembly arranged on the cover body, the explosion-proof valve assembly comprising a valve body and a diaphragm connected to each other, the valve body being connected to the cover body so that the diaphragm blocks the pressure relief hole; wherein the valve body and the cover body are laser-welded.

2. The battery pack housing of claim 1, wherein, The valve body comprises a connecting portion and a mounting portion, the connecting portion being connected to the cover body, and the mounting portion having a through hole penetratingly arranged and communicating with the pressure relief hole; the diaphragm is connected to the mounting portion and blocks the through hole.

3. The battery pack housing of claim 2, wherein, The connecting portion comprises a connecting surface, and the mounting portion comprises a mounting surface, the connecting surface and the mounting surface being respectively located on two sides of the valve body.

4. The battery pack housing of claim 3, wherein, The valve body comprises a first positioning groove, a bottom of the first positioning groove having the mounting surface, and the diaphragm being arranged in the first positioning groove.

5. The battery pack housing of claim 3, wherein, The valve body further comprises a second positioning groove, a bottom of the second positioning groove having the connecting surface, and the cover body further comprising a first protruding portion arranged annularly along a circumference of the pressure relief hole, the bottom of the second positioning groove being connected to the first protruding portion.

6. The battery pack housing of claim 5, wherein, The cover body further comprises a second protruding portion arranged annularly along a circumference of the first protruding portion, and the second protruding portion having a spacing from the first protruding portion.

7. The battery pack housing of claim 6, wherein, A protruding height of the first protruding portion is less than or equal to a protruding height of the second protruding portion.

8. The battery pack housing of any one of claims 2-7, wherein, The diaphragm is welded to the mounting portion.

9. The battery pack housing of any one of claims 2-7, wherein, The mounting portion and the cover body are made of the same material.

10. The battery pack housing of any one of claims 2-9, wherein, The mounting portion and / or the cover body comprise a light-transmitting material.

11. The battery pack housing of claim 10, wherein, The light-transmitting material has a light transmittance greater than or equal to 30%.

12. The battery pack housing of any one of claims 1-11, wherein, The cover body has an outer surface and an inner surface arranged oppositely, and the pressure relief hole penetrates from the inner surface to the outer surface.

13. The battery pack housing of any one of claims 1-11, wherein, The diaphragm comprises a gas-permeable film.

14. The battery pack housing of any one of claims 2-11, wherein, The diaphragm is ultrasonically welded to the mounting portion.

15. The battery pack housing of any one of claims 5-11, wherein, The first protruding portion is a continuous structure and is integrally formed with the cover body.

16. The battery pack housing of any one of claims 6-11, wherein, The second protruding portion is a continuous structure and is integrally formed with the cover body.

17. The battery pack housing of any one of claims 2-11, wherein, The material of the mounting portion and / or the material of the cover body comprises nylon.

18. The battery pack housing of any one of claims 1-11, wherein, The pressure relief hole has a circular cross section.

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