Thermoplastic vulcanizate used in automotive flexible shroud design.

Typically, the shroud around a car or truck's engine fan is mounted to the vehicle body, behind a grille opening, according to the company. In this configuration, a gap is said to be required to allow for relative motion between the rigid shroud and the engine-mounted fan, which is said to reduce airflow efficiency. Mounting a flexible shroud on the engine itself is said to close the gap, benefiting both engine performance and packaging.

NexPrene 1087A thermoplastic vulcanizate (TPV) was used for the flexible shroud portion of the part. NexPrene is an oil-resistant, fully vulcanized thermoplastic elastomer. This flexible material is said to provide good tensile and tear strength with excellent resistance to oil and chemicals, making it ideal for operation in an automotive engine compartment, according to the manufacturer.

NexPrene's maker worked with Sur-Flo Plastics & Engineering to design a secure attachment configuration for the injection molded shroud. The TPV fan cover is overmolded onto a nylon retaining ring, consolidating parts and simplifying assembly. Conventional alternative designs are often said to feature an EPDM cover clamped to an aluminum ring. The use of thermoplastic NexPrene TPV is said to make the design completely recyclable, eliminating the scrap associated with thermoset EPDM.

The flexibility of the NexPrene TPV is said to allow the shroud to be folded back over the ring in preparation for joining the powertrain to the body. This provides an increase in clearance, which significantly improves the assembly process, according to the company. A simple fingertip flip returns the shroud to its operating position. The result is said to be a part that resists engine fluids in operation, and can be refolded for easy service access to the fan.

Better airflow in the new design allowed elimination of an exhaust-gas recirculation cooler.

Solvay Engineered Polymers

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