Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
1998-05-11
2001-07-03
Gray, David M. (Department: 2851)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S279000
Reexamination Certificate
active
06253873
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a gas guide element with sound-absorbent walls for blocking and damping noise spreading from it into main conduits, which element is made up of a flexible inner hose with a metal element, an outer hose, and a soft and likewise flexible intermediate layer of material disposed between the hose.
In a known gas guide element of this kind according to German Patent Publication DE-OS 27 49 665, the inner hose is comprised of a wide-mesh cloth which is provided on its inner side with a spiral wire as a metal element to reinforce it. The outer hose is constituted by a foil, wherein a foamed material is inserted between this foil and the cloth as a intermediate layer of material. The annular end regions of this gas guide element, which is embodied as flexible and linear as well, are closed by glued-on end caps. According to the ideas of the inventor of this gas guide element, the sound is meant to penetrate the mesh of the cloth of the inner hose, into the intermediate layer of material, which is comprised of a foamed material body, and be damped there. Because of the foamed material body, gas guide elements of this kind are neither temperature- nor abrasion-resistant and for this reason are only partially suited for sound blocking and damping. This kind of gas guide elements does not come into consideration for blocking or damping sound emissions of high sound intensity in hot gasses from gas turbines.
In another gas guide element according to German Patent Publication DE 38 30 346 C2, the inner hose, is embodied of a base element, which is both flexible and perforated, on whose exterior an open-pored foam of polymer material is deposited as a sound blocking material, which is encompassed on its outer circumference face by a compact skin as an outer hose. This gas guide element also does not come into consideration for guiding hot gasses and for damping sound intensities connected with them which occur in gas turbines. Also, the relative reductions of the sound pressure level mentioned in these prior publications allow the conclusion that there is only mediocre sound damping, although considered in the absolute, a reduction of the sound pressure level by 3 dB(A) already signifies a reduction of the sound intensity by half.
Furthermore, German Patent Publication DE 32 20 023 C3 and the identical European Patent Publication EP 0 095 582 disclose a gas guide element whose outer layer is comprised of a mainly closed-celled, elastic, thermoplastic foamed material, whereas its inner layer, which is predominantly intended to take on the task of sound blocking, is embodied of an open-celled, soft foamed material, for example a polyurethane soft foam. The two layers are connected either by means of flame lamination or a bonding agent. An intermediate layer of material between the layers in the form of a reinforcing layer is also considered, for example a random fiber structure, cloth or knit cloth of textile and/or glass fibers. This gas guide element also is considered as a sound damper for hot gasses because of its material compositions.
In gas turbines or air driver pumps to be serviced in large-capacity airplanes, for example in those of Boeing aircraft of the type 747; a sound intensity at the turbine exit of 150 dB(A) and a gas temperature of approximately 200° C. must be expected, and at the main turbines, a sound intensity of 165 dB(A) and a core jet temperature of 820° C. must be expected. This kind of sound intensity signifies a threat to human life. The graphs of this prior publication also disclose little regarding the sound intensity reduction in this range.
And finally, U.S. Pat. No. 3,374,856 discloses a gas guide element of another generic type, which is comprised of a corrugated outer hose of rubber-impregnated or plastic-impregnated woven cloth, while the inner hose is made of a synthetic plastic, e.g. urethane caoutchouc. There is no layer of material as an intermediate covering.
FIG. 2
of this patent document shows a bend of a gas guide element of this kind by 180° in order to verify its flexibility. In this prior publication, though, an installation position in this bent form is not even mentioned once in passing. Also, this gas guide element is not suited to blocking or damping sound intensities in hot gasses from gas turbines because of its temperature-sensitive materials.
In addition to these gas guide elements with sound-absorbent walls, there are also a number of sound dampers with nonabsorbing walls, for example according to U.S. Pat. Nos. 2,886,121, 3,187,835, 3,415,337, 3,227,240, European Patent Publications EP 0 346 551 B1, EP 0.493 161 A1, and German Patent Publication DE-OS 2 264 354, which are not the subject of the instant invention.
SUMMARY OF THE INVENTION
Based on this prior art, the object of the invention is to embody a gas guide element with sound-absorbing walls, according to the generic type mentioned at the beginning, which is inexpensive to manufacture and easy to use, in such a way that it assures a considerable reduction of the sound intensity of noises, even in hot and chemically aggressive gasses.
This object is attained in connection with the species mentioned at the beginning in such a way that depending upon the mechanical, chemical, or caloric load exerted by the gas to e guided, the inner hose is comprised of a textile material, a woven cloth made of metal wire, glass fiber, synthetic, natural or ceramic, a nonwoven, or a soft, thin foil of polyurethane, polyamide, polytetrafluoroethylene, or a combination of these materials, which is connected on its outside to weighted metal elements, that the intermediate layer of material is made of a randomly oriented pile of mineral fibers and/or metal fibers And/or shavings and/or chips of entropy-elastic materials and the gas guide element has at least one 360° convolution between its gas inlet and its gas outlet.
The materials from textile to nonwoven in the above list can be uncoated or, for the desired gas- and airtightness, can be coated with an entropy-elastic material, such as natural caoutchouc, rubber, or a plastic, or can be provided with a thin aluminum coating of from 25&mgr; to 50&mgr;, for example.
According to a first embodiment, the weighted metal elements are comprised of individual rings, which enclose the inner hose or hold together the inner hose, which is comprised of tube sections.
According to a second embodiment, the weighted metal elements are comprised of a metal spiral, which holds together the hose on its overlapping lateral ends and is comprised of two spiral-shaped material strips.
According to a third embodiment, the weighted metal elements are comprised of metal pieces which are fastened to the outside of the inner hose in a regular fashion. These heavy metal pieces can be connected with concrete or other heavy, parts, such as ceramic or metal-containing plastic.
According to a fourth embodiment, the weighted metal elements are comprised of a metal spiral which encloses the inner hose and of a pipe or hose which in turn encloses this metal spiral, is provided with the same convolution form, and is connected to the metal spiral by clamps or clipped-in bands, wherein the intermediate space between the inner wall of the pipe or hose and the outer wall of the hose covering is filled with water, high temperature oil, or a melting metal alloy. The correspondingly wound pipe or hose is intended on the one hand to increase the oscillated mass and on the other hand to draw off or supply thermal quantities at the same time via the filling of the intermediate space with different media, for example for cooling or also for heat recovery.
In the attainment according to the invention, the term “convolution” is in no way intended to mean only a “circular convolution”. Thus the convolution on the one hand can be embodied as a circular, archimedean, hyperbolic, or logarithmic spiral or, on the other hand, can be comprised of an elliptical or oval loop up to a knotted convolution, and finally can also have the shape of a serpentine
Norres Albert
Norres Richard
Gray David M.
Striker Michael J.
LandOfFree
Gas guide element with sound-absorbent walls for blocking... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas guide element with sound-absorbent walls for blocking..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas guide element with sound-absorbent walls for blocking... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2559604