Valve application in Exhaust Line Systems

In recent years the demand for the NVH performance of exhaust systems has increased and will increase significantly in the future. Main drivers here are the new pass-by-noise regulation and the new powertrain technologies (e.g. downsizing, down-speeding) paired with volume, weight and costs constraints. In the following paper several application examples for adaptive valve (self-actuated in-pipe valve), in-muffler valve and electric valve are shown and the related benefits on the system performance have been assessed. It is shown that implementing a valve into an exhaust system has a significant influence on the NVH performance. The normally resulting backpressure penalties can be minimized using the right implementation strategy of the valves in the exhaust system. Hence the exhaust system has to be specifically designed for the integration of a valve. All three valve types have additional benefits to their standard application for overall noise reduction and muffler volume reduction, which are analyzed in detail. The adaptive valve, for example, is often used on cars with long pipe routing and has the additional benefit of reducing pipe resonance in the system. Another example, the electric valve, can be couple with CAN data and hence the degree of freedom in application is significantly increased.