Patent ID: 9238990
Filing Date: 2016-01-19
CPC Classification: F01N

Claim Text:
1. A muffler for an exhaust system of an internal combustion engine, the muffler comprising a casing having an inner space, an inlet pipe for sound to enter the muffler, an outlet pipe for sound to exit the muffler, and a separation wall arranged to extend from the inlet pipe to the outlet pipe and being embodied in a manner such as to define first and second acoustical ducts extending through the casing to allow sound propagating along the first acoustical duct to enter the inner space of the casing and to thereafter exit the inner space of the casing again, and to allow sound propagating along the second acoustical duct to acoustically bypass the inner space of the casing, wherein the muffler, including the inner space of the casing, the inlet pipe, the outlet pipe and the separation wall, is sized and shaped to form a high pass filter having a cut-off frequency which is in the range of 200 Hz to 800 Hz; wherein the inlet pipe has an internal inlet pipe opening for sound propagating along the first acoustical duct to enter the inner space of the casing, and wherein the outlet pipe has an internal outlet pipe opening through which sound may exit the inner space of the casing, and wherein the separation wall includes an inner pipe arranged to extend at least from the internal inlet pipe opening to the internal outlet pipe opening; wherein the inlet pipe and the outlet pipe are formed by a continuous pipe completely extending through the casing, the continuous pipe having at least one opening for sound to enter into and exit from the inner space of the casing, and wherein the inner pipe is arranged in said continuous pipe.