A bilayler metamaterial silencer allows substantial fluid through the apparatus, while mitigating the propagation of sound through the apparatus, and while providing a form factor that is significantly more compact than previously-known devices. Moreover, illustrative embodiments allow a designer to specify one or both of the frequency or frequencies at which the apparatus mitigates sound propagation, and/or the bandwidth around the frequency or frequencies at which the apparatus mitigates sound propagation.

A bilayler metamaterial silencer allows substantial fluid through the apparatus, while mitigating the propagation of sound through the apparatus, and while providing a form factor that is significantly more compact than previously-known devices. Moreover, illustrative embodiments allow a designer to specify one or both of the frequency or frequencies at which the apparatus mitigates sound propagation, and/or the bandwidth around the frequency or frequencies at which the apparatus mitigates sound propagation.

A bilayler metamaterial silencer allows substantial fluid through the apparatus, while mitigating the propagation of sound through the apparatus, and while providing a form factor that is significantly more compact than previously-known devices. Moreover, illustrative embodiments allow a designer to specify one or both of the frequency or frequencies at which the apparatus mitigates sound propagation, and/or the bandwidth around the frequency or frequencies at which the apparatus mitigates sound propagation.

A constant velocity muffler assembly for maximizing the exhaust performance of an internal combustion engine includes a muffler that is fluidly coupled to an exhaust pipe of an internal combustion engine to facilitate exhaust gasses to pass through the muffler. A cylinder is disposed within the muffler and the muffler swells outwardly at a middle of the muffler to accommodate the cylinder. The cylinder is oriented to extend along a flow axis of the muffler with respect to the exhaust gasses. In this way the cylinder is configured to deflect sound waves from the internal combustion engine thereby reducing a noise level of the internal combustion engine.

A constant velocity muffler assembly for maximizing the exhaust performance of an internal combustion engine includes a muffler that is fluidly coupled to an exhaust pipe of an internal combustion engine to facilitate exhaust gasses to pass through the muffler. A cylinder is disposed within the muffler and the muffler swells outwardly at a middle of the muffler to accommodate the cylinder. The cylinder is oriented to extend along a flow axis of the muffler with respect to the exhaust gasses. In this way the cylinder is configured to deflect sound waves from the internal combustion engine thereby reducing a noise level of the internal combustion engine.

Methods of and systems for filling a muffler body with a fibrous material prior to completing assembly of the muffler body are disclosed. The methods and systems prevent or otherwise reduce undesired migration of the fibrous material within the muffler body.

Sound waves of an amplitude having a waveform (first value as a function of time and a first maximum) pass into a manifold, which subdivides flow and sound into multiple paths of differing length, yielding transit times offsetting the arrival of each instance of the waveform at an outlet or exit. This minimizes the addition of energy (sound volume, amplitude) arriving at the exit or terminus from each path. Amplitude is thereby reduced (although the waveform shape remains), repeated and offset by the transit time delays of paths discharging at the terminus. One may select the number of paths based on a desired reduction in the sound amplitude. That number is approximately inversely proportional to the ratio of the reduction. For example, six unique paths in an experiment reduced original amplitude (sound volume) to a sixth at an exit.

An improved engine exhaust extractor improves internal combustion engine performance and efficiency. The exhaust extractor includes coaxial inner and outer tubes separating a flow into an inner flow inside the inner tube and an outer flow between the tubes and merging near the exhaust extractor outlet. Helically oriented vanes extend radially from an outer face of the inner tube and reliefs are cut into the inner tube to allow gasses to flow to the outer flow. The inner tube is held in place by end pieces connecting the inner tube to the outer tube. The end pieces include fan blades with wing shaped cross-sections to increase the velocity of exhaust gasses flowing through the exhaust extractor. The fan-like supports and helically oriented vanes cause the outer flow to rotate about a central axis. The exhaust extractor is constructed from only six parts requiring only two welds.

An improved engine exhaust extractor improves internal combustion engine performance and efficiency. The exhaust extractor includes coaxial inner and outer tubes separating a flow into an inner flow inside the inner tube and an outer flow between the tubes and merging near the exhaust extractor outlet. Helically oriented vanes extend radially from an outer face of the inner tube and reliefs are cut into the inner tube to allow gasses to flow to the outer flow. The inner tube is held in place by end pieces connecting the inner tube to the outer tube. The end pieces include fan blades with wing shaped cross-sections to increase the velocity of exhaust gasses flowing through the exhaust extractor. The fan-like supports and helically oriented vanes cause the outer flow to rotate about a central axis. The exhaust extractor is constructed from only six parts requiring only two welds.

A muffler that uses baffles at a 45 relative to one another to create a helical configuration within the cylindrical housing allowing exhaust gases to pass more freely than the prior art mufflers, while maintaining superior noise reduction.