|
Eberspächer engineers have already shown the potential of the anti-noise technique in successfully demonstrating the functions in different test vehicles with four, six and eight-cylinder engines. Decisive steps have been taken in the last two years in making this ready for series production: The durability has been improved considerably, the size of the silencer has been reduced and the system has been successfully applied to diesel vehicles. Initial negotiations for a standard use in future series-production vehicles have already commenced. Hardly surprising really as the sound system has a number of interesting options to offer the car manufacturers. A wide field of applications is presented by the diesel vehicles for example: Spurred on by the successes in performance and propulsion power, they can now even challenge the petrol engines in motorsports! Unfortunately though, the profile of the new and dynamic diesel engine hasn’t been received very well up to now from the acoustics viewpoint. A further example is the fuel-saving cylinder shut-off: This is often associated with undesirable noise changes: The sudden changing from eight cylinders to just four has often made the driver uncertain. ”ActiveSilence” could contribute to authentic sound perceptions in such situations in the future. A special option is the choice of a sound at the press of a button: For example to switch between super quiet, definitely sporty or elegant. With such a feature, the car manufacturer can offer the customer more harmony in the interaction between driving dynamics and acoustics. In addition a high-efficiency silencing by as much as 20 decibel is possible.
From the technical viewpoint, the system is based on the anti-noise principle. A negative mirror-image of the undesired sound waves is generated over a loudspeaker. The opposing waves balance each other out as soon as these exactly superimpose. Major pre-requisites are however the perfect timing and exactly the right level for the anti-noise. Within a partnership, the Bosch-Group develops an electronic control unit with tailor-made engine management system interfaces.
That sound can be counteracted by anti-noise has been known for a long time now. The components suitable for vehicles have not been available up to now for this. The ambient conditions prevailing in an exhaust system are extreme: Excessive heat, moisture, aggressive condensate, a high sound pressure level and severe vibrations. A major milestone was the development of loudspeakers to durably withstand such conditions as well as a silencer design providing optimum protection for the loudspeaker.
|
