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.

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 engine exhaust system includes a catalytic converter, an exhaust conduit connected upstream of the catalytic converter, and an oxygen sensor extending into the exhaust conduit at a first axial position of the exhaust conduit. A valve is located within the exhaust conduit at the first axial position. The valve includes a movable throttle plate having a bypass notch formed on a periphery of the plate. The valve has an open position, and a closed position in which the bypass notch is placed adjacent to the oxygen sensor to guide exhaust over the oxygen sensor.

An exhaust muffler structure to which an exhaust pipe for guiding exhaust gas from an engine to an exhaust muffler is connected, the exhaust muffler structure comprising a catalyst device, included inside the exhaust muffler structure, having a catalyst for purifying the exhaust gas of the engine, wherein the catalyst device has one end connected to the exhaust pipe and is supported inside the exhaust muffler via the exhaust pipe, and a body portion of the catalyst device is supported by a first partition wall having an inner partition wall and an outer partition wall that is on the outer side of the inner partition wall, and the outer partition wall is fixed to the inner wall of the exhaust muffler, and the inner partition wall is fixed to the outer wall of the catalyst device.

An exhaust muffler has an outer cylinder into which an exhaust gas from an engine is introduced and a muffling member made of a foamed ceramic material. The outer cylinder has an inner cylinder through which the exhaust gas passes, a part of the muffling member is supported by an outer wall of the inner cylinder via a holding member. The inner cylinder includes, in an area where the inner cylinder overlaps with the muffling member with respect to axial direction of the inner cylinder, a porous wall portion formed with communication holes communicating an inside and an outside of the inner cylinder. The holding member is arranged at a position where it does not overlap with a part of the porous wall portion, so that muffling effect is enhanced, and the muffling member having a low resistance to impact forces can be supported stably by the inner cylinder.

A muffler for receiving exhaust gas from a combustion engine comprises a shell, first and second inlet pipes each having outlets providing exhaust gas to a mixing chamber within the shell, a first chamber and a second chamber positioned within the shell and a pair of communication pipes each including an inlet receiving exhaust gas from the mixing chamber. Each communication pipe includes an outlet providing exhaust to the second chamber. Each of the communication pipes further includes a Helmholtz opening positioned downstream of the mixing chamber. The Helmholtz openings are open to the first chamber.

A muffler includes a housing defining a first chamber, a second chamber and a third chamber. The muffler includes at least a pair of nested protrusions in communication with an inlet. The pair of nested protrusions is coupled to a respective surface of a pair of plates disposed in the housing such that one of the pair of nested protrusions is spaced apart from and opposite another of the pair of nested protrusions to define a tortuous path that terminates at an outlet defined along an outer circumference. The first chamber is downstream from the pair of plates. The muffler includes a first tube fluidly coupled to the first chamber to direct the exhaust gases from the first chamber to the second chamber. The muffler includes a second tube fluidly coupled to the second chamber to direct the exhaust gases from the second chamber to the third chamber.

The invention concerns a method for unblocking pores in a metal zeolite based selective catalytic reduction (SCR) catalyst. The method includes filling, at least partially, the SCR catalyst with a liquid, the liquid being preferably distilled water. The method includes letting said liquid inside the SCR catalyst enough time to allow said liquid to dissolve, at least partially, the obstructions and to penetrate into the pores. The method includes heating the SCR catalyst at a temperature above the ebullition temperature of the liquid so as to vaporize the part of the liquid remained into the pores, and generate steam flows through the obstructions, the steam flows removing the obstructions and unblocking the pores, wherein no hydrocarbons are injected during the step of heating.

The invention concerns a method for unblocking pores in a metal zeolite based selective catalytic reduction (SCR) catalyst. The method includes filling, at least partially, the SCR catalyst with a liquid, the liquid being preferably distilled water. The method includes letting said liquid inside the SCR catalyst enough time to allow said liquid to dissolve, at least partially, the obstructions and to penetrate into the pores. The method includes heating the SCR catalyst at a temperature above the ebullition temperature of the liquid so as to vaporize the part of the liquid remained into the pores, and generate steam flows through the obstructions, the steam flows removing the obstructions and unblocking the pores, wherein no hydrocarbons are injected during the step of heating.

Provided is a muffler valve 1 which is attached to a separator partitioning the inside of a muffler and opens and closes an exhaust passage according to the pressure of an exhaust gas of an engine. A valve body is swingably supported by a support shaft with respect to a valve seat. The valve body is urged in a closing direction by a spring member externally inserted to the support shaft. A valve seat substrate of the valve seat arranged along the separator is formed in a substantially flat-plate ring shape having an opening in the center. A valve body substrate of the valve body is formed in a flat dish shape having a flat rim. The muffler valve provides excellent handleability during attachment and can reduce the manufacturing cost of the muffler, improve manufacturing efficiency, and maintain high durability of the muffler.