Designfax weekly eMagazine

Subscribe Today!

Archives

View Archives

Partners

Manufacturing Center
Product Spotlight

Modern Applications News
Metalworking Ideas For
Today's Job Shops

Tooling and Production
Strategies for large
metalworking plants

Wheels:
Resonator made of DuPont Zytel helps hybrid sports car sound good

The turbocharged 1.5-liter 3-cylinder petrol engine of BMW's revolutionary i8 plug-in hybrid sports car is equipped with a sound-modelling resonator made of DuPont's high-temperature- and chemical-resistant Zytel PLUS polyamide resin.

 

 

 

 

The racy BMW i8 plug-in hybrid sports car features a resonator made of glass fiber-reinforced DuPont Zytel PLUS 95G35, which is tuned to reduce the typical high-frequency air intake sound to a lower level to improve the driving experience.

Zytel PLUS is a high-performance polyamide, produced with DuPont's proprietary SHIELD technology, which provides superior long-term resistance to high temperatures and aggressive fluids typical of under-the-hood applications.

Due to its function, the resonator has a relatively large volume, but -- thanks to an optimized design in terms of wall thicknesses and the use of this high-stiffness and high-strength grade of Zytel PLUS -- it weighs just 1.5 kg (3.3 lb). Installed between the air filter and turbocharger in the rear of the i8, it is part of the air management system of the sports car's compact 1.5-liter 3-cylinder gasoline engine.

The resonator was developed in a close collaboration between BMW Group, DuPont Performance Materials, and MANN+HUMMEL. MANN+HUMMEL, a Tier-1 supplier, makes use of its experience in hot gas welding to assemble two injection-molded parts: the perforated interior tube as well as an outer tube measuring about 40 cm in length with integrated fittings for fuel-tank ventilation and blow-by inlet -- to create the broadband resonator. An additional air duct, including an elastic bellows segment made of an unreinforced soft nylon grade, is then mounted to connect the resonator to the air-intake filter, while the system's opposite end fits to the intake side of the turbocharger.

Thanks to the choice of Zytel PLUS, the resonator has long-term resistance to temperatures from -40 deg C to 190 deg C, as well as hot engine gases and fluids.

Just why did the designers choose Zytel PLUS?

"In light of the high-temperature environment due to close proximity to the exhaust gas system and direct contact with chemicals such as road salt, we quickly ruled out standard polyamide materials for this demanding application due to their insufficient long-term heat and chemical resistance," says Florian Janiak, Polymer Specialist/Global Production Strategy, MANN+HUMMEL. "Zytel PLUS 95G35 performs well in such a hot and confined operating environment, and what's more, it retains most of its weld strength even after extended exposure to very high temperatures, where traditional materials would drop significantly. We also found it very easy to mold and weld in our hot gas process."

DuPont's proprietary SHIELD technology combines several innovations, including a new polymer backbone, polymer modifications, and a special set of additives that can double or triple the service life of standard nylon on exposure to hot environments and aggressive chemicals such as hot oil, automotive coolants, and road salt. DuPont Zytel PLUS 95G35, the core product of the Zytel PLUS family, shows no significant drop in its ability to withstand load -- even over 4,000 hours of testing at 180 deg C -- whereas a traditional PA 66 GF35's ability to withstand load is cut to less than half. This resilience makes it attractive for use in cylinder head covers, resonators, exhaust mufflers, and oil pans.

Want to know more about the ~$140,000 BMW i8? Read the Car & Driver review here.

Source: DuPont

Published April 2016

Rate this article