Cord-Reinforced Composite Exhaust Hangers for Optimizing NVH, Durability and Positioning in Automotive Applications 2012-01-0803

In connecting an exhaust pipe system to the body of a vehicle, a compromise between a soft attachment for good noise, vibration and harshness (NVH) behavior and a rigid attachment for optimum exhaust system positioning and hanger life is necessary. Classical exhaust system hangers, made entirely of rubber, cannot meet these conflicting requirements.

Technology using reinforcement cording and woven fabric scrim has been used in automotive tires for many years, and scrim-reinforced rubber has been used in coolant hoses, steering couplings (“rag joints”), simple exhaust pipe isolators/hangers and other components. The presented research has culminated in a new technology in exhaust system hanger solutions comprised of a composite elastomeric rubber material reinforced with laid-in directional polyester cording. This approach in exhaust system hanger design offers development engineers the possibility of providing anisotropic and tunable stiffness characteristics to meet NVH requirements while accommodating compact size, high strength and high durability for system positioning and hanger life requirements.

These findings are illustrated with physical test and analytical results, including a vibrational movement analysis of an exhaust unit relative to the car body, as well as comparison of acoustic measurements made inside the passenger compartment. A stiffness comparison between classical rubber hangers and cord-reinforced composite hangers will be illustrated by means of quasi-static bench test results.