Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2001-11-21
2004-01-27
Nappi, Robert (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S255000, C181S269000, C181S272000
Reexamination Certificate
active
06681888
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silencing apparatus to fit between an air intake duct for combustion air, for instance combustion air released from an engine turbine and an air exhaust duct through which air or combustion fluid exits, for instance towards a thermal exchanger.
2. Description of Related Art
Silencing apparatus of this type are already known from the prior art. According to the prior art, said silencing apparatus usually comprise a main hollow body with a circular, cylindrical shape and both an input connection and an output connection also respectively with a circular, cylindrical shape, each of which having a diameter smaller than the diameter of said main body, such that said input connection and output connection are fitted to either side of said main body.
At least one part forms a partition with the internal surface of said main hollow body, wherein said partition defines at least two toric chambers within the internal volume of said main body, which are defined between the diameter of said body and the diameter of said connections in a transversal perspective. Said toric chambers communicate directly with a virtual cylinder, which is defined by the diameter of said connections and within which the fluid moves from one connection to the other, by means of a circular slit which extends over the entire periphery of said virtual cylinder.
The apparatus according to the prior art feature many disadvantages. Firstly, the dimensions of said circular slits are too large in order to facilitate the manufacturing process. Increased losses of the inherent charge of the fluid transiting within the resonance chambers thus occur as air transits between said input connection and said output connection.
Moreover, the positioning of said partitioning part is critical when implementing this type of silencing apparatus. The width of said toric chambers must indeed precisely depend upon the frequency of the sound waves to be absorbed. Consequently, said part must be very accurately positioned. This is a time-consuming task, which is a problem within the scope of mass manufacturing. Finally, the manufacturing process of said main hollow body is itself complicated.
The present invention aims to remedy the above disadvantages by providing a new silencing apparatus fitted between an air intake duct and an air or fluid exhaust duct, which is easy to manufacture and notably does not require many stamping tools, whilst also reducing said loss of charge within said silencer.
BRIEF SUMMARY OF THE INVENTION
According to a preferred embodiment of the present invention, the silencing apparatus is fitted between a first air or fluid intake duct and a second air or fluid exhaust duct, said silencing apparatus being notably fitted between an engine turbine and a thermal exchanger; said silencer comprising a cylindrical main hollow body, a cylindrical input connection and a cylindrical output connection with a smaller straight section than the straight section of said main body, and at least one partitioning part defining with the internal surface of said main hollow body at least two toric chambers within the portion of said main body located around the virtual cylinder defined by the virtual extension of each of said connections toward one another, each of said toric chambers communicating directly with said virtual cylinder following a slit extending over the entire periphery thereof; is characterized in that said toric chambers are partly separated from said virtual cylinder by said partitioning part and/or one and/or both ducts between which said silencer is fitted.
The external walls of both the input connection and the output connection and an auxilliary wall formed by the partitioning part, which separates both chambers shaped as a body are used in order to minimise the dimension of the communicating slit between said chambers in the direction of the flow as well as the main flow of fluid, such that the incidental loss of charge is reduced in a simple manner without however requiring additional tools or parts.
In an improved embodiment of the present invention, one or a plurality of partitioning parts are cylindrical parts, the generating curvature of which includes a first straight segment defining a separating wall between the toric chambers and the virtual cylinder, a second straight segment defining a separating wall between two toric chambers and a third straight segment defining a corner with said second segment in a perspective parallel to the flow of fluid. An annular recess is shaped within the internal surface of the hollow body and said corner butts against a lateral wall of said recess such that an accurate positioning of the partitioning part is easily achieved when said third segment is welded to said recess. Accordingly, an accurate dimension of the resonance chambers is also easily achieved, whereby mass manufacturing is thus possible without however having to precisely measure the positioning of the partition for every instance.
In an improved embodiment of the present invention, the dimension of the width of said recess equals the dimension of said third straight segment of said partitioning part. The precision of the positioning is thus increased.
In an improved embodiment of the present invention, said main hollow body comprises two identical bells which can be joined to one another at the level of their respective outer edge.
In an improved embodiment of the present invention, said bells comprise a cylinder, the generating curvature of which comprises a first straight segment parallel to the flow axis and corresponding to a diameter equal to the diameter of the input duct or output duct, a second straight segment parallel to said first straight segment but farther away from the axis of said cylinder, and a third straight segment farther away still from the axis of said cylinder such that a recess is defined with the third segment of the other bell in the perspective of the axis of said cylinder, ie. the axis of the flow of fluids.
In an improved embodiment of the present invention, a third auxiliary toric chamber is implemented which communicates with the inside of said virtual cylinder by means of an aperture extending over less than three hundred and sixty degrees, notably less than two hundred and forty degrees, preferably less than one hundred and twenty degrees.
In an improved embodiment of the present invention, said third chamber is implemented by adding a second partition with a shape identical to the shape of the first partition.
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Martin Edgardo San
Renner Kenner Greive Bobak Taylor & Weber
Westaflex-Automobile
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