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Monday, March 27, 2023

Foldable gasket tackles battery pack sealing complications

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

Security and effectivity are core factors of focus for immediately’s battery system builders. Batteries for brand 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 might result in conditions that endanger the occupants or considerably scale back the battery lifecycle. Correct sealing of the battery inside its housing is important for mitigating these dangers, because the seal is the primary line of defence in opposition to undesirable detrimental influences. The battery should be accurately sealed to keep away from ingress regarding mud and moisture. Electrical conductivity of the seal should even be thought-about for electrical grounding of the duvet.

The incumbent gaskets, largely based mostly on adhesives and silicone elastomers, are widespread for sealing battery housings, as are type in place (FIP) options, that are injected onto the housing and left to remedy. Each current challenges when it comes to 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. Because of this, Datwyler has engineered an revolutionary 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 a complete, which may be specified and positioned at intervals in accordance with 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 won’t be accepted, due to this fact when designing the steel insert, Datwyler can management the scale 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 throughout the parameters required at sure heights. Not like FIP gaskets, there is no such thing as a starting or an finish part, the place you must make sure that there is no such thing as a small channel to guard in opposition to the results of corrosion.

The exact and dependable set up of the foldable gasket is vital, as battery producers are making greater density battery methods and their housings have gotten extra advanced and numerous. These extra advanced designs want a extra exact gasket to make sure the seal integrity just isn’t compromised and the steel factor of the answer ensures that is the case. The steel is normally 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 part. The result’s a sealing resolution that delivers enhanced sturdiness and in addition 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 don’t have this capacity.

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

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

Simulation delivers optimised outcomes

Numerical simulation of the sealing efficiency of foldable gaskets is a core factor in your complete design course of. Such simulations permit the understanding of the correct mechanical and thermal conduct of the seal underneath excessive situations, guaranteeing the effectiveness and reliability of the seal in varied crucial conditions. This effort begins with a two-dimensional finite factor mannequin, through which the variations of the sealing strain alongside the seal lips are evaluated (see determine 1). As soon as the contact strain and space on the seal meet the necessities for the precise outlined efficiency, the simulation effort continues with conducting a three-dimensional finite factor modelling with a purpose 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 elements.

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 throughout the gasket; (b) the variation of contact strain on the boundary of the seal

Sustainability in-built

Battery makers are additionally contemplating the potential for opening the battery pack a number of instances over its lifetime for inspection and upkeep. The foldable gasket makes this doable. If an FIP gasket is used, one facet of the gasket is completely adhered onto the housing. This implies when the gasket is opened it can’t be eliminated. The foldable gasket may be eliminated and simply changed as there is no such thing as a adhesive between the gasket and the housing. The fastening resolution makes use of common 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 tip 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 finally recycling, battery producers expertise the advantages of an impressive sealing resolution.

In regards to the authors: Dr Amir Yazdani is Superior Know-how Improvement Supervisor at Datwyler. Andreas Proksch is  Product Supervisor Electrification at Datwyler

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