Electronic muffler assembly with exhaust bypass

DETAILED DESCRIPTION The present invention relates generally to active noise cancellation systems, and particularly to active noise cancellation systems for use in quieting the engine exhaust noise of an internal combustion engine.
More particularly, this invention relates to an exhaust processor assembly including a mixing chamber receiving combustion product generated by a vehicle engine and a housing containing noise cancellation speakers for delivering cancelling sound waves to the mixing chamber.
Until recently, mufflers used to silence vehicle engines have been limited to passive devices.
In a conventional muffler, a stream of exhaust gases is routed from the engine into the muffler where it is generally directed through various flow obstacles such as tubes and baffles provided inside the muffler.
The purpose of the flow obstacles in a muffler is to reflect a portion of the sound waves associated with the exhaust gases back towards the engine.
The change of acoustic impedance causes the sound energy to be reduced.
The use of such conventional baffle arrangements causes back pressure to develop in the exhaust system.
As the stream of exhaust gases encounter the baffles or other obstacles to flow, a pressure wave is propagated back through the exhaust system to the engine, requiring additional power from the engine just to expel the exhaust gases.
This power requirement results in reduced maximum power available from a given engine while decreasing fuel efficiency.
Therefore, a muffler that is configured to eliminate or substantially reduce back pressure in an exhaust system and includes an active noise attenuation device would represent a great improvement over conventional mufflers.
Active noise attenuation devices use acoustic sensors, control systems, and speakers or transducers to produce sound wave interference.
Using sound wave interference, undesirable noise is attenuated by mixing cancelling sound waves produced by the active noise attenuation device with the undesirable noise