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Application Description

Gustav Wahler uses DuPont™ Vespel® TP polyimide bushings to position and guide cylindrical operating rods of EGR (Exhaust Gas Recirculation) slip-in valves. The valves are used in four and six cylinder stratified- charged gas engines. Located behind the pre-catalytic converter and operating at temperatures of up to 200°C, the valves regulate the quantity of exhaust gas re-circulated into the combustion air to reduce NOx emissions.

Benefits Gained

Vespel® TP bushings combine excellent friction and wear performance
with a very low thermal expansion coefficient. These properties allow
consistently smooth operation of the valves during their fast paced and
precise opening and closing. Because Vespel® TP parts can be injection
molded, they offer a high degree of design freedom, enhanced
functionality and significant long-term benefits compared to equivalent
metal components.

Materials Selected and Why

Vespel® TP bushings exhibit

  • High level of wear, chemical and temperature resistance
  • Lower weight than metal or ceramic
  • Cost-efficient and precise injection molding of the bushings in a single
    shot, without post-machining
  • Good acoustic attenuation, reducing noise emissions from the valves
  • Low levels of friction on the surface to help prevent formation of
    contamination deposits and allow consistent, predictable operating
    forces over the life of the valves

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Direct Customer
Gustav Wahler GmbH u. Co. KG
Hindenburgstraße 146, D-73730