Devices, systems and methods are described for reducing noise emitted from active aerosol and bioaerosol collection devices. The system includes a noise reducing muffler between the collection component and the air mover and a noise reducing baffle at the outlet of the air mover. The muffler reduces higher frequency noises emitted from the air mover inlet while the baffle reduces lower frequency noises emitted from the air mover outlet. Placement of the muffler between the collection component and the air mover eliminates the potential for loss of particles to the muffler prior to collection.

A muffler, for an internal combustion engine exhaust system, includes a muffler housing (12) with a housing jacket (14) elongated in a housing longitudinal axis (A) direction and with an outer panel (16) connected to the housing jacket at both axial end areas thereof to define a muffler interior (18). An inner panel (20) is arranged in and divides the muffler interior. A muffling unit (24) includes an exhaust-gas-carrying inner pipe (26), an outer pipe (28) enclosing the inner pipe and muffling material (32) arranged between the inner pipe and the outer pipe. The inner pipe is accommodated in an opening (48) of an inner panel and in an opening (40) of one of the outer panels or of an additional inner panel. The outer pipe is permanently connected to the inner panel or/and to one of the outer panels or to the additional inner panel.

A muffler, for an internal combustion engine exhaust system, includes a muffler housing (12) with a housing jacket (14) elongated in a housing longitudinal axis (A) direction and with an outer panel (16) connected to the housing jacket at both axial end areas thereof to define a muffler interior (18). An inner panel (20) is arranged in and divides the muffler interior. A muffling unit (24) includes an exhaust-gas-carrying inner pipe (26), an outer pipe (28) enclosing the inner pipe and muffling material (32) arranged between the inner pipe and the outer pipe. The inner pipe is accommodated in an opening (48) of an inner panel and in an opening (40) of one of the outer panels or of an additional inner panel. The outer pipe is permanently connected to the inner panel or/and to one of the outer panels or to the additional inner panel.

Disclosed is a silencer for fuel cell vehicles. The silencer for fuel cell vehicles includes a housing having an inlet configured to receive air and hydrogen flowing into the housing therethrough, an outlet, and a condensation water drain hole configured to discharge condensation water to the outside therethrough, a distribution plate disposed in the housing and having distribution holes to distribute air and hydrogen flowing into the housing, a rotary plate disposed in the housing closer to the outlet than the distribution plate, a motor connected to the rotary plate to rotate the rotary plate, and an anti-freezing unit extending from one end of the rotary plate to the condensation water drain hole.

Disclosed is a silencer for fuel cell vehicles. The silencer for fuel cell vehicles includes a housing having an inlet configured to receive air and hydrogen flowing into the housing therethrough, an outlet, and a condensation water drain hole configured to discharge condensation water to the outside therethrough, a distribution plate disposed in the housing and having distribution holes to distribute air and hydrogen flowing into the housing, a rotary plate disposed in the housing closer to the outlet than the distribution plate, a motor connected to the rotary plate to rotate the rotary plate, and an anti-freezing unit extending from one end of the rotary plate to the condensation water drain hole.

There is provided a method for filling a silencer with glass fiber, for filling an internal space between a case and an inner pipe with glass fiber in a silencer in which a porous inner pipe penetrates through a pair of through holes in the case, the method including shifting the inner pipe in a penetrating direction from a normal position where the inner pipe is secured to the case, inserting a nozzle auxiliary portion into an interior of the case from a through hole opened by the inner pipe being shifted, supplying glass fiber into the interior of the case from a nozzle of a glass fiber supply machine connected to the nozzle auxiliary portion, and filling the internal space between the case and the inner pipe with glass fiber.

There is provided a method for filling a silencer with glass fiber, for filling an internal space between a case and an inner pipe with glass fiber in a silencer in which a porous inner pipe penetrates through a pair of through holes in the case, the method including shifting the inner pipe in a penetrating direction from a normal position where the inner pipe is secured to the case, inserting a nozzle auxiliary portion into an interior of the case from a through hole opened by the inner pipe being shifted, supplying glass fiber into the interior of the case from a nozzle of a glass fiber supply machine connected to the nozzle auxiliary portion, and filling the internal space between the case and the inner pipe with glass fiber.

A silencing apparatus is provided with a shell, ventilation pipes communicating with the inside of the shell, insertion holes which are respectively formed in the shell so as to have sizes smaller than surrounding skirt parts and allow the ventilation pipes to be loosely inserted in, and partitions partitioning the inside of the shell. In the silencing apparatus, at least, a sound-absorbing chamber partitioned by the partition and positioned adjacent to the insertion hole is filled with a sound-absorbing fiber material, and a sound-absorbing fiber material filling gap between the insertion hole and the ventilation pipe is closed by an annular closing member. To provide a silencing apparatus allowing a sound-absorbing chamber to be filled with sound-absorbing fiber material without a gap, even in a complicated configuration having the inside of a shell partitioned by a partition.

The present disclosure provides a sound absorbing material. The sound absorbing material comprises MFI-structural-type zeolite. The MFI-structural-type zeolite comprises a framework, and the framework comprises SiO.sub.2 and AlO.sub.3, and the mass ratio of Si to Al in the framework is less than 200 and not less than 50. The present disclosure also provides a speaker box applying the sound absorbing material. The sound absorbing material provided by the present disclosure and the speaker box using the sound absorbing material can further improve the performance of the speaker box, reduce the failure of zeolite and improve the performance stability of the speaker box.

The present disclosure provides a sound absorbing material. The sound absorbing material comprises MFI-structural-type zeolite. The MFI-structural-type zeolite comprises a framework, and the framework comprises SiO.sub.2 and AlO.sub.3, and the mass ratio of Si to Al in the framework is less than 200 and not less than 50. The present disclosure also provides a speaker box applying the sound absorbing material. The sound absorbing material provided by the present disclosure and the speaker box using the sound absorbing material can further improve the performance of the speaker box, reduce the failure of zeolite and improve the performance stability of the speaker box.