Patent Application
20240421424
The present disclosure relates generally to venting of byproduct heat from batteries. More specifically, the present disclosure provides to a venting assembly for mitigating thermal runaway events that may occur in relation to rechargeable battery packs or housings.
Thermal runaway is a catastrophic battery failure event which is a cascade failure that begins when the heat generated inside a rechargeable battery cell, such as a lithium-ion battery cell, is not dispersed to its surroundings. Thermal runaway can occur due to a number of operational factors including, but not limited to overcharging, end of life age, float charge voltage, and external battery damage, such as for example in an automotive accident. If the excess heat that is generated is not fully or partially remedied by heat mitigators or vents, an unplanned runaway condition could result in a catastrophic failure.
Once internal battery temperatures rise too high without mitigation (as low as 250 degrees F. in as little as four minutes time duration), a domino effect happens where a battery cell or cells can begin to catastrophically fail, such a failure can then further increase the reaction rates. Such an event with a suspect battery can quickly lead to sudden system failure, an explosion with burning projectiles, and/or an uncontrolled fire.
Vent assemblies for rechargeable battery packs are known in the industry. Known vent assemblies provide pressure equalization and mitigation of gas pressure buildup inside the battery pack during both normal operation and runaway events. The vents also include features that guard against contaminants, dirt, water, etc., while also providing pressure equalization with the ambient environment. Further these vents provide heat ventilation for temperature cycling during normal operation. While the existing vents will provide an escape route for large amounts of gas and pressure build up during a runaway event, such existing vents do not offer any protection from heat, flame or projectiles that may be generated and expelled from the battery housing in the event of an explosive failure or battery fire.
The present disclosure provides a novel battery vent assembly that includes an expanded metal filter element which acts as a heat sink to cool and overheating battery. Further, the vent assembly acts as a particulate filter and flame arrestor which prevents and/or reduces flames and particulate slag projectiles from being expelled outside an individual cell or bank of cells in a battery.
The disclosure employs Directional Flow Expanded Metal (DFEM) and Variable Expanded Metal (VEM) filter technology as a failsafe device to mitigate an unplanned thermal runaway event inside a lithium-ion battery system and to capture any potential explosive particles and arrest flames preventing the unwanted propagation of flames and debris outside the battery.
In some embodiments, the filter element is formed as a multilayer cylindrical collar. In other embodiments, the filter element is a flat multilayer filter element.
A VEM/DFEM filter element utilizes directional fins and associated plethora of openings offset in overlapping layers to create a light weight, low-cost tortuous path centrifuge or cyclone effect for gases or particles passing through the filter. The fins and holes are offset from layer to layer within the wrap of the collar filter and are designed to immediately spin the flames and burning particles into a 90 degree pathway in relation to the input flame flow direction. This spinning of the flame and the offset layer to layer, creates a cooling effect to act as a thermodynamic heat sink (at both sub-sonic or supersonic mass flow, flaming gas speeds) and to further arrest the flame by forcing the flame particles one direction while allowing the cleaned, cooled air generated by the heating battery source, to more easily move different from, or opposite to the flaming particles. As a result, air flows more freely at a cool temperature, to collar the flame in as low as 5 milliseconds, before any flames or particles reaches a battery vent exit port.
Once a thermal runaway ignites into a flame, the flame can burn and or explode into burning projectiles very fast inside a battery. The collar filter vent must separate the flaming particles in as low as only a few milliseconds of time. Thus, the filter's vent openings are sized differently in each successive layer. The openings are sized on a gradient, so as not to aggressively hamper a slag filled flaming fluid-flow. This avoids a collar from prematurely plugging with slag. The collar filter can do this once the particles are removed by creating more fine holes that can be added more quickly into the filter layers to filter smaller and smaller burning particles more quickly while avoiding a plug which can create undo internal battery backpressure.
The particles in the flame, as well as the undesirable external battery heat are thus better trapped inside the subsequent layers of the metal heat sink filter as “captured flame” particles, and the generated air is able to exit the battery system being less incumbered at a far cooler temperature that is reduced by up to 90% of its burning flame temperature in less than one second time.
Testing has shown that flames and particles of a burning gas generate (lab mockup) are better removed up to 100% with DFEM and or VEM acting as a collar filter vent, and with far less filter weigh than non-variable layers, and non-cyclone type collar filters.
Exemplary embodiments will now be described further by way of example with reference to the following examples and figures, which are intended to be illustrative only and in no way limiting upon the scope of the disclosure.
Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the device and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure. Further, in the present disclosure, like-numbered components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-numbered component is not necessarily fully elaborated upon. Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed systems, devices, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, devices, and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can easily be determined for any geometric shape. Further, to the extent that directional terms like top, bottom, up, or down are used, they are not intended to limit the systems, devices, and methods disclosed herein. A person skilled in the art will recognize that these terms are merely relative to the system and device being discussed and are not universal.
Turing to
The vent base portion 20 may have a cylindrical bottom wall 26 with a vent port 28 extending downwardly. The exterior of the vent port 28 may be threaded for removable assembly to the vent opening 16 in the battery housing 14. A vent path 32 extends through the vent port 28 and through an opening in the bottom wall 30 into the interior of the vent assembly 18. The vent cover 22 has a top wall 34 and downwardly extending sidewalls 36 which are secured to the base portion 20 by welding or other fastening means consistent with automotive manufacturing standards. The top wall 34 and/or sidewalls 36 may have vent openings 38 therein through which gases may enter or exit. Directional flow of gas out of the vent may be seen by the arrows in
Turning to
The shape of the slit opening 40 and or fins in the collar vents provide the advantage to force the flame path to be longer than it would in a traditional flow path, which go nearly straight through a wire mesh vent opening, or straight expanded metal filters, or perforated metal, or wire wound filer openings. This longer vent flow path in a VEM or DFEM filter collar can extinguish the flame in as little as 2 offset row layers by creating turbulence of the flame stream, which is highly desired when trying to either remove the flame quickly, and the resultant generated high temperature particle filled gases.
As illustrated in
Further details regarding Directional Flow Expanded Metal (DFEM) and Variable Expanded Metal (VEM) Filters may be found in U.S. Pat. No. 10,717,032 (Greenwood et. al), as well as in U.S. Pat. No. 10,676,062 (Adamczyk et. al.), the entire contents of which are incorporated herein by reference.
Turning to
The vent base portion 220 may be rectangular, square, circular or any other suitable geometry to match a corresponding vent port on the battery housing 14, and may have a bottom wall 226 with one or more vent ports or openings 230. The vent assembly 200 may be secured to the battery housing 14 by means of fasteners 232 extending through aligned openings 234 in the vent base 220 and cover 222. The vent cover 222 has a top wall 240 and may have one or more vent openings 242 therein through which gases may enter and exit.
Referring back to
It can therefore be seen that the exemplary embodiments described herein provide unique and novel thermal runaway vent assembly which is effective for mitigating both heat, flame, and explosive particle discharge from a battery housing. For these reasons, the instant invention is believed to represent a significant advancement in the art, which has substantial commercial merit.
While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.
This application is a divisional application of U.S. patent application Ser. No. 17/714,602, filed Apr. 6, 2022, which is related to and claims priority from earlier filed U.S. Provisional Patent Application No. 63/281,346, filed Nov. 19, 2021, the entire contents of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63281346 | Nov 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17714602 | Apr 2022 | US |
| Child | 18817879 | US |
