Foldable gasket tackles battery pack sealing complications


Amir Yazdani and Andreas Proksch discover how Datwyler’s new folding gasket addresses the challenges of current expertise

Security and effectivity are core factors of focus for at the moment’s battery system builders. Batteries for brand spanking new mobility options current new challenges in comparison with these utilized in inner combustion engines (ICE). Points equivalent to thermal runaway and corrosions of battery elements may result in conditions that endanger the occupants or considerably scale back the battery lifecycle. Correct sealing of the battery inside its housing is crucial for mitigating these dangers, because the seal is the primary line of defence in opposition to undesirable detrimental influences. The battery should be appropriately sealed to keep away from ingress referring to mud and moisture. Electrical conductivity of the seal should even be thought of for electrical grounding of the duvet.

The incumbent gaskets, largely primarily based on adhesives and silicone elastomers, are widespread for sealing battery housings, as are kind in place (FIP) options, that are injected onto the housing and left to remedy. Each current challenges by way of dealing with throughout set up, positioning on the tray, efficacy after curing and the power to facilitate each on-going upkeep and end-of-life recyclability. Consequently, Datwyler has engineered an progressive resolution—the foldable gasket—which delivers a sealing resolution for battery packs that overcomes all of those points. The answer combines superior elastomer supplies with skinny steel plates, foldable at factors and stiff as an entire, which might be specified and positioned at intervals in response to distinctive half geometries, permitting for exact mounting both manually or robotically.

Determine 1. Working precept of Datwyler’s foldable gasket

Challenges and options

Usually, for the battery housing and its related seals, the tolerances are very restrictive and should adjust to IP6x or equal ingress safety parameters. Any gaps is not going to be accepted, subsequently when designing the steel insert, Datwyler can management the size exactly with minimal margin for error. Engineers use the elastic properties of Datwyler’s rubber materials, which may be very exact, to fulfil the necessities inside the parameters required at sure heights. In contrast to FIP gaskets, there isn’t any starting or an finish part, the place it’s a must to be sure that there isn’t any small channel to guard in opposition to the consequences of corrosion.

The exact and dependable set up of the foldable gasket is essential, as battery producers are making larger density battery programs and their housings have gotten extra advanced and various. These extra advanced designs want a extra exact gasket to make sure the seal integrity just isn’t compromised and the steel aspect of the answer ensures that is the case. The steel is often the identical as that used for the housing itself and the floor is anodised and handled to make sure a robust bond with the elastomer element. The result’s a sealing resolution that delivers enhanced sturdiness and likewise electrical conductivity, that means electrical energy can switch simply from the higher cowl to the decrease casing by way of the gasket, which avoids corrosion as a consequence of electrical energy build-up. Standalone pure rubber and FIP options should not have this skill.

Determine 2. Explosion view of a battery with a foldable gasket (in blue)

Lastly, electromagnetic interference (EMI)—which might have an effect on elements equivalent to sensors or crucial management models—can be mitigated by way of EMI shielding supplies, which can be utilized to formulate the rubber aspect of the foldable gasket.

Simulation delivers optimised outcomes

Numerical simulation of the sealing efficiency of foldable gaskets is a core aspect in your complete design course of. Such simulations enable the understanding of the correct mechanical and thermal habits of the seal underneath excessive circumstances, making certain the effectiveness and reliability of the seal in varied crucial conditions. This effort begins with a two-dimensional finite aspect mannequin, by which the variations of the sealing stress alongside the seal lips are evaluated (see determine 1). As soon as the contact stress and space on the seal meet the necessities for the precise outlined efficiency, the simulation effort continues with conducting a three-dimensional finite aspect modelling with the intention to consider the quantity of pre-stress on the bolts required to maintain the foldable gasket in place. This pre-stress additionally ensures the specified electrical conductivity between the housing components.

Lastly, The final step focuses on the simulation of your complete battery housing related with the foldable gasket, in order that the seal integrity alongside your complete seal lip is ensured. These units of simulation duties facilitate the optimisation course of in the course of the design of the gasket with the end result being optimised geometrical dimensions, materials properties and mounting forces.

(b) Determine 3. The outcomes of a two-dimensional simulation of a four-lip foldable gasket design: (a) the utmost principal pressure inside the gasket; (b) the variation of contact stress on the boundary of the seal

Sustainability in-built

Battery makers are additionally contemplating the opportunity of opening the battery pack a number of instances over its lifetime for inspection and upkeep. The foldable gasket makes this attainable. If an FIP gasket is used, one aspect of the gasket is completely adhered onto the housing. This implies when the gasket is opened it can’t be eliminated. The foldable gasket might be eliminated and simply changed as there isn’t any adhesive between the gasket and the housing. The fastening resolution makes use of normal self-piercing rivets or M5/M6 screws for ease of opening. This additionally permits simpler disassembly with zero injury of the sealing gasket when inspection or upkeep is required, or when the battery reaches the top of its helpful lifespan.

From an Ecodesign perspective, the design rules of the foldable gasket imply that, from preliminary transportation, dealing with and set up to efficient software, upkeep and in the end recycling, battery producers expertise the advantages of an excellent sealing resolution.

Concerning the authors: Dr Amir Yazdani is Superior Expertise Growth Supervisor at Datwyler. Andreas Proksch is  Product Supervisor Electrification at Datwyler


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