3M contribution to feature on wider EV technologies
With comparatively little heat being generated by the powertrain of an electric vehicle, the HVAC (Heating Ventilation and Airconditioning) system needs an electric element to warm the airstream – not ideal when electrical energy is at a premium. Similarly, the lack of a front-end accessory drive means that the compressor must also be electrically powered.
Abs Master, newly appointed head of 3M’s European Automotive Acoustics Group, says that this has led to criticism of some EVs for poor HVAC performance. “This is usually because either the electrical element can’t generate enough heat or because the battery charge is low so the power management system cuts high consumption accessories like heating and airconditioning,” he explains.
A substantial improvement can be made by insulating the cabin. “You wouldn’t consider installing a bigger boiler in your house before fitting insulation, but that is what we do with our cars. The challenge in automotive applications is that the insulation material must provide the required thermal performance without adding significantly to the weight or packaging.”
3M’s solution is a light-weight, non-woven polymer called Thinsulate™. Master says that the source of its excellent thermal insulation characteristics is a low density web comprised of more than 50% microfibers that ensure a high air content. The non-woven, low density structure also makes it flexible and very compressible, so it is easy to fit even where space is limited or where there are compound curves. And being hydrophobic means that no additional water protection is required.
In the automotive industry, Thinsulate has traditionally been used for acoustic absorption. “The low density web gives it excellent medium and high frequency absorption characteristics, which is exactly what is required to reduce electric motor noise,” says Master. “Managing these frequencies will provide a more premium cabin sound, while the move to Thinsulate can cut the weight of the acoustic pack by up to 40 percent compared with traditional materials.”
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