Battery Pack Venting Layout for High-Temperature Cell Discharge Gas
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Solution Overview
Problem
High-temperature discharged gas from discharge valves in lithium ion cells can thermally damage the exterior case and pose safety risks due to ignition and flame escape.
Innovation Solution
A battery pack design with a flameproof cover, diffusion gap, expansion space, and fume ventilation holes that redirect and dissipate the discharged gas, reducing its energy before expulsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If through holes are provided in the exterior case to expel discharged gas, then gas venting function is improved, but the exterior case is damaged by high-temperature gas
Solution Approach 1:
A flameproof cover made of heat-resistant material (such as mica or ceramic) is introduced as an intermediary component between the discharge valve and the exterior case. This mediator withstands the high-temperature discharged gas (400°C or higher) and redirects it toward the through holes, preventing direct contact with and thermal damage to the exterior case while maintaining effective gas venting.
2Strength
If heat-resistant spacer is disposed counter to discharge valve to prevent case damage, then exterior case protection is improved, but high-temperature gas still damages the case
Solution Approach 1:
The flameproof cover is designed with specific material properties (heat resistance up to 400°C or higher) and geometric features (inclined surface at 45-60 degrees) that change the parameters of gas flow. The inclined surface redirects the gas flow direction, causing it to exit through the side surface rather than directly impacting the case, thereby reducing thermal damage while maintaining protection.
3Stress or pressure
If discharged gas is jetted vigorously from discharge valves, then pressure relief function is improved, but ignition and flame escape risks increase
Solution Approach 1:
The flameproof cover redirects the discharged gas from a direct linear path toward the case to a different dimensional path, directing it to exit through the side surface of the case via through holes. This dimensional change in gas flow path reduces the risk of ignition and flame escape by controlling the discharge direction away from flammable environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents the exterior case from being thermally damaged and minimizes the risk of ignition by diffusing and cooling the discharged gas effectively.
Implementation Method 1
diffusion gap 28 is provided between discharge valve side end surface 1a of battery cell 1 and a case inner surface counter to discharge valve side end surface 1a, with flameproof cover 6 disposed in diffusion gap 28... discharged gas jetted from the discharge valve collides with flameproof cover 6, fills expansion space 25 via diffusion gap 28
Implementation Method 2
expansion space 25 for the discharged gas diffused by flameproof cover 6 is provided inside case 2... direction changing portion 29 that changes a direction of the gas flowing inside case 2 is provided at a corner of the case. The discharged gas jetted from the discharge valve collides with flameproof cover 6, fills expansion space 25 via diffusion gap 28, is changed in direction in expansion space 25
Implementation Method 3
case 2 has a plurality of fume ventilation holes 27 through which discharged gas jetted from the discharge valve is expelled out of the case
Data Source
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AI summary
To improve safety by suppressing a harmful effect caused by high-temperature discharged gas jetted from discharge valves of cells. A battery pack includes battery cell (1) including a discharge valve, and case (2) housing battery cell (1). Case (2) includes a plurality of fume ventilation holes (27) through which discharged gas jetted from the discharge valve is expelled out of the case, and diffusion gap (28) is provided between discharge valve side end surface (1a) of battery cell (1) and a case inner surface, with flameproof cover (6) disposed in diffusion gap (28). Additionally, expansion space (25) for the discharged gas diffused by flameproof cover (6) is provided inside case (2), and the direction of expelling the discharged gas is changed to a direction intersecting a direction in which the discharged gas is jetted form the discharge valve. Expansion space (25) communicates with diffusion gap (28) and with fume ventilation holes (27), and a direction changing portion that changes a direction of the flowing gas is provided at corners of the case. In the battery pack, the discharged gas jetted from the discharge valve collides with flameproof cover (6), fills expansion space (25) via diffusion gap (28), is changed in direction in expansion space (25) to diffuse into the plurality of fume ventilation holes (27), and is expelled out of the case.