JP2011242052A - Sound-deadening duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound-deadening duct arranged under the roof etc. of a house, used for indoor ventilation, capable of effectively absorbing noise generated from an air sending source and sound of a wind made to flow within the duct and having excellent heat insulation property.SOLUTION: A reinforcing strip body 3 is spirally wound around the outer circumferential surface of a duct inner wall 1 made of nonwoven fabric including an infinite number of fine ventilation holes 2, a string-like buffer heat insulating strip material 4 is wound on the reinforcing strip body 3, an independent foaming synthetic resin belt material 5A is disposed between upper surfaces of adjacent buffer heat insulating strip material parts, at the same time, opposite side edge surfaces of the adjacent independent foaming synthetic resin belt material parts are integrally connected, thereby, a tubular duct outer wall 5 is formed, and a space part 7 formed between the duct inner wall 1 and the duct outer wall 5 is enlarged by the reinforcing strip body 3 and the buffer heat insulating strip material 4 arranged on the reinforcing strip body 3 to effectively absorb a sound.

Description

  The present invention relates to an improvement of a silencer duct which is piped on a ceiling or the like of a house and performs ventilation in the room and ventilation for cooling and heating the room.

  In recent years, in order to improve the living environment, houses having airtightness are generally built, and accordingly, it is required to stably ventilate and heat / heat the airtight rooms. In order to satisfy such a requirement, a duct is arranged using the ceiling or wall of a house, and external air from a blower source such as a blower is supplied into the room through the duct, or between upper and lower layers. Although an air supply system that circulates air is used, noise generated by driving a blower or the like and wind sound when circulating in the duct are propagated through the duct into the room and give unpleasant feeling.

  For this reason, for example, as described in Patent Document 1, a tubular inner wall made of a sheet-like material having air permeability such as a non-woven fabric, and the outer peripheral surface of the inner wall are spirally wound at a constant pitch. A rigid synthetic resin reinforcing strip, and a strip-shaped foamed synthetic resin material having a certain thickness interposed between adjacent reinforcing strips. There is known a silencer duct composed of a heat insulating layer provided with sound absorbing holes at small intervals in the direction and an outer wall made of a non-breathable soft synthetic resin sheet covering the heat insulating layer.

  According to this silencer duct, when the sound wave enters the sound absorption hole provided in the heat insulating layer through the fine ventilation holes provided in the inner wall made of nonwoven fabric or the like, the inner wall that attenuates the sound energy and closes the sound absorption hole When the sound wave enters the space inside the sound absorption hole from the fine ventilation hole, the sound wave diffuses suddenly and diffuses at the peripheral wall of the sound absorption hole and diffuses the air in the sound absorption hole. It is possible to exert a silencing effect by vibrating.

JP 2006-313043 A

  However, according to the silencer duct as described above, in order to improve the sound absorption effect by the sound absorption holes provided in the heat insulation layer, it is desirable to enlarge the sound absorption holes. As a result, the heat insulation effect is reduced, and the heat insulation layer is divided by the reinforcing strips without being continuous in the length direction of the pipe. Further, when this silencer duct is curved, a tensile force is generated on the outer peripheral surface curved in a convex arc shape, and a compressive force is generated on the inner peripheral surface curved in a concave arc shape. As a result, the interval between the adjacent reinforcing strips is narrowed, and the heat insulating layer interposed in the interval portion is compressed to reduce the sound absorbing hole, and further, the sound absorbing hole is closed to reduce the noise reduction effect.

  In addition, since the area of the inner wall portion made of a nonwoven fabric or the like that closes the sound absorbing holes is relatively small, there is a problem that the amplitude width by the sound wave is small and a sufficient sound absorbing action cannot be exhibited.

  On the other hand, in order to improve the silencing effect, for example, as shown in FIG. 3, a heat insulating layer is formed between the reinforcing strips 12 and 12 spirally wound around the outer peripheral surface of the duct inner wall 11 having air permeability such as a nonwoven fabric. A tubular heat-insulating layer 13 serving as an outer wall of the duct is formed by spirally winding a strip-shaped foamed synthetic resin material having a constant thickness and a constant width on the reinforcing strip 12 without interposing the end faces thereof facing each other. If the sound absorbing duct is formed by covering the outer peripheral surface of the heat insulating layer 13 with the soft synthetic resin coating layer 14, a relatively wide space (air) is formed between the facing surfaces of the inner wall 11 and the heat insulating layer 13. Layer) 15 can be formed, and the space 15 can improve the silencing effect compared to the sound absorbing hole.

  However, according to the sound absorbing duct configured as described above, the band-shaped foamed synthetic resin material for forming the heat insulating layer 13 is manufactured on the reinforcing strip 12 spirally wound around the outer peripheral surface of the duct inner wall 11 at the time of manufacture. When winding while applying tension to the portion, the portion of the inner peripheral surface of the foamed synthetic resin material that bites into the reinforcing strip 12 increases or decreases due to fluctuations in the tension, or the top surface of the reinforcing strip 12 There is a problem in that not only a part that is separated from the substrate is generated and a stable product cannot be obtained, but a part that cannot provide a sufficient silencing effect is generated.

  Further, also in this silencer duct, when the duct is bent, as shown in FIG. 4, the inner peripheral surface curved in a concave arc shape is adjacently reinforced by the compressive force in the length direction generated on the inner peripheral surface. When the insulation layer between the strips 12 and 12 is bent and deformed with the reinforcement strips 12 and 12 as a fulcrum and bent inward, the insulation layer portion hits the inner wall 11 in the portion that is greatly biting into the reinforcement strip 12. As a result, the space 15 is greatly narrowed, and there is a problem in that the silencing effect is remarkably lowered when the curve construction is performed. In addition, when the adjacent strip-shaped foamed synthetic resin material is spirally wound in a state where the opposing side end surfaces are simply joined without being integrally connected to each other by fusion or the like, when bending construction is performed There arises a problem that a gap is generated between the opposing side end faces and the heat insulating function is lowered.

  The present invention has been made in view of such problems, and its object is to have a stable structure capable of exhibiting a uniform silencing action over the entire length, and to further enhance the silencing effect. An object of the present invention is to provide a muffler duct that can be improved and can exhibit a good muffling effect without lowering the heat insulating function even when bent.

  In order to achieve the above object, the silencer duct of the present invention has a tubular duct inner wall made of a sheet-like material having air permeability and flexibility, and a constant outer peripheral surface of the duct inner wall. A reinforcing strip made of hard synthetic resin that is spirally wound with a pitch of, and a string that is spirally wound on the reinforcing strip with the same pitch as that of the reinforcing strip and is superimposed on the reinforcing strip. And a closed foam synthetic resin belt-shaped material having a certain width and thickness are spirally wound while the opposing side end surfaces are joined together, and the inner peripheral surface thereof is the buffer heat insulating strip. A duct outer wall made of a tubular heat insulating layer fixed integrally to the outer surface of the duct and a soft synthetic resin coating layer covering the outer peripheral surface of the duct outer wall.

  In the silencer duct configured as described above, the invention according to claim 2 is characterized in that the soft synthetic resin coating layer covering the outer peripheral surface of the outer wall of the duct is made of a soft synthetic resin strip having a certain width. A soft synthetic resin strip is overlaid on the outer surface of the independent foam synthetic resin strip forming the outer wall of the duct, and one end of the strip is placed between the opposite end surfaces of the adjacent foam synthetic resin strip. It is fixed to the opposite end faces by heat fusion so as to intervene, and one side end of the soft synthetic resin strip is inward from the opposite end face of the adjacent independent foam synthetic resin strip. The outer surface of the string-like buffer heat insulating strip is integrally fused and fixed to the inner peripheral surface of the independently foamed synthetic resin strip through this one side end.

  Further, the invention according to claim 3 is characterized in that the string-like cushioning heat insulating material is made of the same independent foamed synthetic resin as that of the independent foamed synthetic resin belt-like material, and the invention according to claim 4 is characterized in that the inner wall of the duct is fine. It consists of the nonwoven fabric which provided the countless ventilation hole.

  According to the first aspect of the present invention, the muffler duct is formed by helically reinforcing a reinforcing strip made of hard synthetic resin at a constant pitch on the outer peripheral surface of a tubular inner wall made of a sheet-like material having air permeability and flexibility. In addition, a closed foam synthetic resin belt-shaped material having a certain width and thickness is spirally wound on this reinforcing strip through a string-like buffer heat insulating strip while joining the opposing side end surfaces together. And since the duct outer wall which consists of a tubular heat insulation layer which has adhered the inner peripheral surface to the outer surface of the above-mentioned buffer heat insulation strip is provided, it is spirally wound around the outer peripheral surface of the inner wall. By the reinforcing strip made of hard synthetic resin, the entire duct can be held in the shape of a circular tube having pressure resistance and flexibility, and a duct that is easy to construct and exhibits good ventilation can be provided. Of course, when manufacturing the duct, the outer wall of the duct Depending on the magnitude of the tension, even if the tension fluctuates, the independent foamed synthetic resin strip to be formed is wound on the buffer heat insulation strip spirally wound on the reinforcement strip while applying tension. Thus, it is possible to always connect the opposite ends of the adjacent foamed synthetic resin strips accurately on the buffer heat insulating strip while varying the amount of compression and the amount of biting into the reinforcing strip. It is possible to provide a duct having a stable and accurate structure that exhibits uniform heat insulation and noise reduction over the entire length.

  Furthermore, when the sound wave enters the space on the outer peripheral surface side of the duct inner wall through the duct inner wall made of a sheet material having air permeability, the sheet-like material area between adjacent reinforcing strips is large. It can vibrate effectively with the reinforcing strips adjacent to each other as a fulcrum and exerts an effective sound-absorbing action. In addition, sound waves pass through the inner wall of the duct and are independently foamed between adjacent reinforcing strips. When entering a space with a horizontally long cross section formed between the opposing surfaces of the resin strip and the inner wall of the duct, the space is a heat insulating layer by a buffer heat insulating material that is superimposed on the reinforcing strip. Since the space between the above-mentioned closed foam synthetic resin strip forming the outer wall of the duct and the inner wall of the duct is widened and formed in a large and large space portion, it diffuses rapidly in this space portion. Effectively mute In addition, sound absorption is performed while repeatedly scattering and reflecting sound waves on the opposed surfaces of the independent foamed synthetic resin belt-shaped material forming the space, the inner wall of the duct, and the buffer heat insulating strip, and an excellent silencing effect can be obtained. .

  In addition, when this muffler duct is bent when performing curved construction, in the inner peripheral wall portion of the hose curved in a concave arc shape where compressive force is generated, the heat insulating layer portion between adjacent reinforcing strips by the compressive force As described above, the buffer heat insulating strip in which the space between the facing surfaces of the independent foam synthetic resin belt-shaped material forming the heat insulating layer and the inner wall of the duct overlaps on the reinforcing strip even when the inner wall is bent in the inner diameter direction. Since the heat insulating layer is directly expanded on the reinforcing strip as compared with the duct provided, a space portion having a predetermined silencing effect can be ensured.

  In addition, the shock-absorbing material and the heat-insulating layer made of the synthetic foam synthetic resin band-like material can provide a heat-insulating action, and can exhibit an excellent heat-insulating function. In addition, in the inner peripheral wall portion of the hose that is curved into a concave arc shape that generates a compressive force when the duct is bent, the heat insulating layer portion between adjacent reinforcing strips is wide as described above. The duct can be bent smoothly without difficulty while being easily bent inward toward the portion.

  In addition, the heat insulating layer is made of a closed foam synthetic resin strip having a certain width and thickness, and the reinforcing strips and the buffer heat insulation are formed on the inner wall of the duct while bonding the opposing side end surfaces to each other and fixing the bonded portions together. Since it is formed into a tubular heat insulation layer that is continuous over the entire length of the duct by spirally winding it through the strip material, it can be used for straight-line construction as well as for independent foamed synthetic resin strips even if curved construction is performed. A uniform heat insulating effect can be achieved over the entire length without causing a gap or the like between the opposing side end surfaces.

  According to the second aspect of the present invention, the outer peripheral surface of the duct outer wall made of the heat insulating layer is covered over the entire length by the soft synthetic resin coating layer made of the soft synthetic resin strip having a certain width. In addition to having a good external appearance, one side end of the soft synthetic resin strip is interposed between the opposing end surfaces of the adjacent closed-cell synthetic resin strip, and is integrally fixed to these opposing end surfaces by heat fusion Because of this, the opposite end faces of the adjacent foamed synthetic resin strips are firmly integrated by this soft synthetic resin strip-like heat fusion so that a tubular thermal insulation that provides uniform thermal insulation over the entire length A layer can be formed.

  Furthermore, the buffer heat insulating strip material is provided on the inner peripheral surface of the independent foam synthetic resin strip through one side end of the soft synthetic resin strip projecting inward from the opposite side end surface of the adjacent independent foam synthetic resin strip. Since the outer surface of the material is fused and fixed, the independent foam synthetic resin strip and the buffer heat insulating strip are integrated by one side end of the soft synthetic resin strip and have an excellent heat insulation effect. Since the buffer heat insulating strip is locked by elastic deformation to the top of the reinforcing strip that is spirally wound on the inner wall of the duct, the outer wall of the duct and the inner wall of the independent foam synthetic resin strip are formed. It is possible to provide a sound absorbing duct having a stable form without causing reluctance in the longitudinal direction.

  According to the invention which concerns on Claim 3, since the said string-shaped buffer heat insulating material consists of the same independent foam synthetic resin as the independent foam synthetic resin strip | belt material, with the independent foam synthetic resin strip | belt material which has formed the heat insulation layer The heat insulating effect can be improved by the buffer heat insulating strip. Further, according to the invention of claim 4, the duct inner wall is made of a nonwoven fabric provided with innumerable fine ventilation holes, so that the gap formed between the fibers of the nonwoven fabric together with the infinite number of ventilation holes provided in the nonwoven fabric. Therefore, an excellent sound absorbing effect can be obtained.

The partial vertical side view of a part of this invention silencer duct. The longitudinal side view of the state bent. The partial vertical side view of a part of silencer duct which does not provide buffer insulation strips. The longitudinal side view of the state bent.

  A specific embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a muffler duct A is provided with innumerable fine ventilation holes 2 penetrating between inner and outer surfaces at small intervals in a circumferential direction and a length direction. A duct inner wall 1 made of a non-woven fabric having a constant diameter, and having a constant height and a constant width wound around the outer peripheral surface of the duct inner wall 1 in a spiral manner over the entire length at a constant pitch. A hard synthetic resin reinforcing strip 3 and a string-like buffer heat insulating strip 4 spirally wound on the reinforcing strip 3 at the same pitch as the reinforcing strip 3 and superimposed on the reinforcing strip 3. And an independent foamed synthetic resin strip 5a having a constant width and a constant thickness. By spirally winding the opposite end faces together A duct outer wall 5 comprising a tubular heat insulating layer formed, and the inner peripheral surface of the heat insulating layer being integrally fixed to the outer surface of the buffer heat insulating strip 4, and the outer peripheral surface of the duct outer wall 5 are entirely covered. It is comprised from the soft synthetic resin coating layer 6 which has coat | covered.

  The width in the length direction of the duct in the independent foamed synthetic resin strip 5A is formed to be equal to the spiral pitch of the reinforcing strip 3 spirally wound around the outer peripheral surface of the duct inner wall 1. Both end portions in the width direction are placed on opposite half portions of the outer surfaces of the buffer heat insulating strip portions 4a and 4a superimposed on the adjacent reinforcing strip portions 3a and 3a wound in a spiral. In this state, it is disposed between the upper surfaces of the buffer heat insulating strips 4a and 4a in a erected state, and between the opposing surfaces of the duct outer wall 5 and the duct inner wall 1 made of the independent foam synthetic resin strip 5A. A space 7 having a horizontally long rectangular cross section is formed between the opposing surfaces of the buffer heat insulating strips 4a and 4a superimposed on the adjacent reinforcing strips 3a and 3a. It should be noted that a plurality of linear small-diameter reinforcing strips 3 'thinner than the reinforcing strip 3 are heat-sealed to the outer peripheral surface of the duct inner wall 1 between the adjacent reinforcing strips 3a and 3a at every small interval. The duct inner wall 1 is retained in a cylindrical or tube shape together with the reinforcing strip 3.

  The nonwoven fabric forming the duct inner wall 1 is made of synthetic resin fibers such as polypropylene or polyester, and a strip-shaped nonwoven fabric portion 1a in which a long strip-shaped nonwoven fabric having a width substantially equal to the pitch of the reinforcing strip 3 is spirally wound first. Then, the duct inner wall 1 having a constant diameter is formed by spirally winding the opposite side end portions of the belt-shaped non-woven fabric portion 1a which are wound next to each other and thermally fusing them. The reinforcing strip 3 is made of an olefin-based hard synthetic resin such as polypropylene or polyester, and is spirally wound around the outer peripheral surface of the duct inner wall 1 with a pitch substantially equal to the width of the strip-shaped nonwoven fabric. Are integrally fixed to the adjacent end portions of the strip-shaped nonwoven fabric portions 1a and 1a by heat-sealing. The reinforcing strip 3 is formed in a triangular shape with a gradually narrowing width from the bottom surface, which is the inner end surface fixed on the duct inner wall 1, toward the top portion, which is the outer end portion, and the outer end portion is convex. Although it is formed in the projecting end portion 30 that is curved in an arc shape and engages the inner surface of the buffer heat insulating strip 4, it is not limited to this cross-sectional shape, but is formed in other appropriate cross-sectional shapes. Also good.

  The above-mentioned string-like buffer heat insulating strip 4 superimposed on the reinforcing strip 3 is made of an independent foamed synthetic resin such as a foamed polyethylene resin, which is the same as the strip-shaped material 5A made of the independent foamed synthetic resin forming the duct outer wall 5. And is formed in a rectangular cross section having a width slightly larger than the width of the reinforcing strip 3 and a thickness substantially equal to the height of the reinforcing strip 3, and is superimposed on the reinforcing strip 3 to reinforce the reinforcing strip 3. Are wound spirally at the same pitch, and the protruding end 30 of the reinforcing strip 3 is bitten into the center of the inner surface of the reinforcing strip 3 to be engaged with the reinforcing strip 3.

  The independently foamed synthetic resin belt-shaped material 5A forming the duct outer wall 5 made of the heat insulating layer is made of a foamed polyethylene resin, and one outer end surface thereof is gradually inclined outward from the outer surface side toward the inner surface side. The above-mentioned covering has a cross-sectionally parallelogram shape formed on an inwardly inclined end surface formed on an inwardly inclined end surface, and the other side end surface is gradually inclined inward from the outer surface side toward the inner surface side. The layer 6 is a soft synthetic material that can be heat-sealed with the independent foamed synthetic resin strip 5A and the buffer heat insulating strip 4, such as a non-breathable polyethylene resin having a constant width wider than that of the closed foam synthetic resin strip 5A. It is made of a resin strip 6a, and this soft synthetic resin strip 6a is superposed on the outer surface of the independent foam synthetic resin strip 5a forming the duct outer wall 5 without being heat-sealed. One end 6a1 is connected to the buffer insulation strip. It is interposed between the opposed side end surfaces of the adjacent foamed synthetic resin strip-shaped material portions 5a, 5a facing each other on the outer surface of the material portion 4a, and is integrally fixed to these opposed side end surfaces by heat fusion.

  Further, one side end 6a2 of the soft synthetic resin strip 6a projecting inwardly from the opposite end surface of the adjacent closed foam synthetic resin strip 5a, 5a is connected to one side of the outer surface of the buffer heat insulating strip 4a. The inner surface of the other end portion of the independent foamed synthetic resin strip member 5a is integrally fixed to the one end 6a2 of the soft synthetic resin strip member 6a by heat fusion. ing.

  Briefly explaining the method of manufacturing the muffler duct A configured as described above, a belt-shaped nonwoven fabric having air permeability provided with innumerable ventilation holes 2 over the entire surface is formed on a side end facing a molding rotating shaft (not shown). The duct inner wall 1 is formed by spirally winding the parts while being heat-sealed, and a semi-molten rigid synthetic resin reinforcing strip 3 is formed from a molding nozzle (not shown). While extruding, it is spirally wound at a constant pitch on the strip-shaped nonwoven fabric forming the duct inner wall 1. At this time, the reinforcing strips 3 are integrally fixed on the superposed portions by winding and cooling while superposing the superposed portions of the side ends of the belt-like nonwoven fabric at a high heat temperature of the reinforcing strips 3. Let A plurality of small-strength reinforcing strips 3 ′ in a semi-molten state are also spirally wound on a strip-shaped nonwoven fabric forming the duct inner wall 1 in a plurality of parallel and parallel states.

  Further, a buffer heat insulating strip 4 made of an independent foam synthetic resin string is spirally wound at the same pitch as the reinforcing strip 3 while being superimposed on the reinforcing strip 3, and the reinforcing strip is applied by the winding pressure (tension). While the center portion of the lower surface of the buffer heat insulating strip 4 to be pressed against the projecting end portion 30 of the body 3 is elastically compressed and deformed, the projecting end portion 30 is bitten into the lower surface of the reinforcing strip 3 so that the buffer end portion 30 has a buffer heat insulating strip. 4 is locked. Subsequent to the buffer heat insulation strip 4, the independent foam synthetic resin belt-shaped member 5a formed in the cross-sectionally long parallelogram shape above the adjacent half portions on the outer surface of the adjacent buffer heat insulation strip 4a, 4a. To be installed.

  When the independent foamed synthetic resin strip 5a is installed between the upper surfaces of the adjacent buffer heat insulating strips 4a, 4a, a soft synthetic resin strip in a semi-molten state on the outer surface of the closed foam synthetic resin strip 5A. 6a is overlapped, and one end 6a1 of the soft synthetic resin strip 6a is heat-sealed to the outward inclined end surface of the independent foam synthetic resin strip 5A, and the soft synthetic resin is formed from the outward inclined end surface. The one end 6a2 of the strip 6a is protruded inward, and in this state, the independent foam synthetic resin strip 5a is placed between the upper surfaces of the adjacent buffer heat insulating strips 4a and 4a. Erection.

At this time, the inside of the independently foamed synthetic resin belt-shaped material portion 5a wound in a single turn on the outwardly inclined end surface of the independent foamed synthetic resin belt-shaped material portion 5a previously wound in the spiral direction. The one-side end 6a1 is formed by joining the direction-inclined end face through the one-side end 6a1 of the above-mentioned semi-molten soft synthetic resin strip 6a1.
A tubular duct outer wall 5 which is a heat insulating layer is formed by winding with a constant helical pitch while integrally fusing the inclined opposite end surfaces of the independent foam synthetic resin strip-like material portions 5a and 5a together. .

  Further, the above independent foaming at the one side end 6a1 of the semi-molten soft synthetic resin strip 6a in which the opposite end surfaces of the adjacent foamed synthetic resin strip 5a, 5a are integrally heat-sealed together. From the above-mentioned foamed synthetic resin string-like material spirally wound on the reinforcing strip 3 through the one end 6a2 having a constant width projecting inwardly from the opposite end surfaces of the synthetic resin strips 5a, 5a. Simultaneously heat-bonding the inner surface of the side surface of the inwardly inclined synthetic resin strip 5a on the outer half of the outer surface of the buffer heat insulating strip 4a, and at the same time, this independent foam synthetic resin strip Independent foaming of the soft synthetic resin strip 6a covering the outer surface of 5a by spirally winding the other end 6a3 projecting from the closed foam synthetic resin strip 5a to the other side first. The soft synthetic resin strip 5a on the synthetic resin strip 5a is softly bonded to one end of the synthetic resin strip 6a. Producing muffler duct by going to form a resin coating layer 6.

  The silencing duct A thus obtained is piped on the ceiling of a house and the like to ventilate the room through a silencing duct from an air source such as a blower. A tubular duct outer wall 5 made of a strip-shaped material 5A and a buffer heat insulating strip 4 made of an independent foamed synthetic resin that supports the duct outer wall 5 from the inside can exhibit an excellent heat insulating action, and can also be used as a blower or the like. Noise generated by driving and wind noise when circulating in the duct enters between the fibers of the non-woven fabric forming the duct inner wall 1, and converts the sound energy into thermal energy by friction and vibration of the fibers, and mute In addition, it is possible to prevent noise from being propagated in the room.

  Furthermore, innumerable fine ventilation holes 2 drilled in the duct inner wall 1 communicate with a wide space portion 7 between the facing surfaces of the duct inner wall 1 and the duct outer wall 5 made of the independent foam synthetic resin strip 5A. Therefore, when the sound wave enters the space portion 7 through these vent holes 2, the sound energy is attenuated, and when the sound wave passes through the vent hole 2 and enters the wide space portion 7, it diffuses rapidly. The air in the space 7 can be vibrated while being repeatedly irregularly reflected on the opposing surfaces of the duct inner wall 1 and the duct outer wall 5 forming the space 7 to absorb and mute noise. In addition, since the adjacent buffer heat insulating strips 4a and 4a forming the space 7 and the duct outer wall 5 are made of an independent foamed synthetic resin, the sound wave is transmitted through these buffer heat insulating strips 4a and 4a. It is possible to improve the silencing effect by randomly irregular reflection by the rough surface with the duct outer wall 5.

  In addition, when the sound deadening duct A is bent when it is bent, a reinforcing strip portion 3a adjacent to the inner duct peripheral wall portion curved in a concave arc shape in which a compressive force is generated in the lengthwise direction is formed by the compressive force. Even if the independent foam synthetic resin belt-like material portion 5a, which is the outer wall portion of the duct between the buffer heat insulation stripe portions 4a and 4a on 3a, bends inward, it overlaps on the reinforcement stripe 3 and the reinforcement stripe 3 Since the thickness of the space portion 7 is sufficiently thick to allow the independent foamed synthetic resin belt-shaped material portion 5a to be bent by the buffer heat insulating strip 4, the silencer duct A can be easily bent to a desired degree of bending. In addition, it is possible to ensure the size of the space portion 7 necessary for the silencing action.

  Further, when the silencer hose A is bent, in the outer duct peripheral wall portion curved in a convex arc shape in which a tensile force is generated in the length direction, the adjacent independent wall forming the duct outer wall 5 by the tensile force. The foamed synthetic resin strips 5a, 5a are about to be separated from each other, but the opposite end surfaces of the independent foamed synthetic resin strips 5a, 5a are covered with the outer surface of the independent foamed synthetic resin strip 5A. Since it is integrally connected by heat fusion of the one end 6a1 of the soft synthetic resin strip 6a, uniform insulation is provided continuously over the entire length of the tube without any gaps. Has an effect.

A Silencer duct 1 Duct inner wall 2 Vent hole 3 Reinforcement strip 4 Buffer insulation strip 5 Duct outer wall
5A Independently foamed synthetic resin strip 6 Soft synthetic resin coating
6a Strip material made of soft synthetic resin 7 Space

Claims (4)

  A tubular duct inner wall made of a sheet-like material having air permeability and flexibility, a rigid synthetic resin reinforcing strip wound spirally around the outer peripheral surface of the duct inner wall at a constant pitch, and A string-shaped buffer heat insulating strip that is spirally wound on the reinforcing strip at the same pitch as the reinforcing strip and superimposed on the reinforcing strip, and an independent foam synthetic resin strip having a certain width and thickness, A duct outer wall formed of a tubular heat insulating layer that is spirally wound while integrally joining the opposing side end surfaces and whose inner peripheral surface is integrally fixed to the outer surface of the buffer heat insulating strip, and the duct outer wall A muffler duct comprising a soft synthetic resin coating layer covering an outer peripheral surface.   The above-mentioned soft synthetic resin coating layer covering the outer peripheral surface of the duct outer wall is made of a soft synthetic resin belt-shaped material having a certain width, and the independent synthetic foam synthetic material forming the duct outer wall. It is superposed on the outer surface of the resin strip, and one end thereof is interposed between the opposing end surfaces of the adjacent independent foam synthetic resin strip, and is integrally fixed to these opposing end surfaces by heat fusion. Furthermore, one side end of this soft synthetic resin strip is protruded inward from the opposite side end face of the adjacent closed synthetic resin strip, and the independent foam synthetic resin strip is passed through this one end. The silencer duct according to claim 1, wherein the outer surface of the string-like buffer heat insulating strip is integrally fused and fixed to the inner peripheral surface of the material.   The silencer duct according to claim 1 or 2, wherein the buffer heat insulating strip is made of the same independent foam synthetic resin as that of the independent foam synthetic resin strip.   The silencer duct according to claim 1, wherein the inner wall of the duct is made of a nonwoven fabric provided with countless fine ventilation holes.

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