JP6401926B2 - Flexible duct - Google Patents

Description

  The present invention relates to a flexible duct in an air conditioning facility for a building.

  In general, buildings such as office buildings and detached houses are provided with air conditioning equipment for air conditioning and ventilation. The air conditioning equipment includes a duct through which air passes. In recent years, as this type of duct, demand for lightweight and flexible flexible ducts (see Patent Documents 1 and 2, etc.) is increasing.

  The flexible duct of Patent Document 1 is obtained by sequentially winding an inner film body, a heat insulating layer, and an outer film body around the outer periphery of a core material made of a spiral metal wire. A gas flow path is formed inside the core material and the inner membrane body. The inner membrane body is made of a non-woven band, and this band is wound in a spiral tube shape and held from the inner peripheral side by a core material.

  In the flexible duct of Patent Document 2, the inner membrane body is held from the outer peripheral side by the core material. This inner membrane is made of resin. However, the specific composition and properties of the resin are not described.

Japanese Utility Model Publication No. 4-136445 ([0006], [0008]) Japanese Patent No. 4791428 ([0004], [0028])

A conventional flexible duct is held exclusively by a core material. The inner membrane body mainly functions as a cover that separates the heat insulating layer from the gas flow path, and hardly contributes to the shape retention strength of the flexible duct. Therefore, the only way to increase the shape retention strength of the flexible duct is to increase the strength of the core material by, for example, increasing the cross section of the core material. However, doing so increases the material cost. Moreover, since the core material is a spiral wire, it has almost no resistance against the external force from the side to the gap between the spiral pitches. Therefore, the portion of the flexible duct that falls between the spiral pitch gaps is easy to dent, and once recessed, it is difficult to return. If the spiral pitch of the core material is shortened in order to prevent this, the total length of the core material increases and the material cost becomes higher.
An object of this invention is to reduce the required intensity | strength of a core material by making the intima body bear the shape retention strength of a flexible duct in view of the said situation.

In order to solve the above-mentioned problems, the present invention includes a spiral tubular inner membrane body defining a gas flow channel on the inside, and a spiral metal core material along the peripheral surface of the inner membrane body. In the flexible duct in which edges facing each other with a pitch deviation from each other are fixed by the core member, the intima body autonomously has a spiral tubular state or a substantially flat state in the width direction. It is characterized by comprising a strip made of a resin having a shape retaining property that can be retained.
Thereby, the intima body can bear the shape retention strength of the flexible duct in cooperation with the core material. That is, the flexible duct can be maintained in a tubular shape (annular section) not only by the core material but also by the inner membrane body. Therefore, the required strength of the core material can be reduced. In particular, when an external force is applied from the side to a portion corresponding to the gap between the helical pitches of the core material in the flexible duct, the external force can be received by the intima body so that the portion corresponding to the gap between the helical pitches is not recessed so much. Can be. In addition, when the external force is released, the dent of the portion that falls between the spiral pitch gaps can be returned to the original state by the elastic restoring force of the intima body. Furthermore, the supporting force with respect to the heat insulation layer arrange | positioned at the outer periphery of an inner membrane body can be improved.
Further, as a secondary effect, when it is necessary to bend the inner membrane body once in the width direction when forming the inner membrane body into a spiral tube while being fastened with the core material, When the force that bent the body in the width direction is released, the intima body can return to a substantially flat state in the width direction by its own elastic restoring force. Therefore, it is possible to reliably and easily perform molding of the intima body and fastening with the core material.

The inner membrane body preferably contains polyethylene terephthalate.
This ensures the shape retention of the intima body. Moreover, the humidity and temperature of the gas which flows through a gas flow path can be maintained, and the moisture retention property and heat retention property of a flexible duct can be ensured.

The inner membrane may be a single layer of polyethylene or a laminate of polyethylene terephthalate and polyethylene. Alternatively, the inner membrane body may be a nylon single layer, a polypropylene single layer, or a laminate of nylon and polypropylene.
This ensures the shape retention of the intima body.

  According to the present invention, the intima body can bear the shape retention strength of the flexible duct in cooperation with the core material. Alternatively, the strength of the core material can be supplemented by the inner membrane body. Thereby, the required strength of the core material can be reduced.

FIG. 1 shows a first embodiment of the present invention and is a perspective view of a flexible duct. FIG. 2 is a cross-sectional view of a part of the flexible duct cut along the axis of the flexible duct. FIG. 3 is a side view showing a state of molding the inner membrane body and the core material of the flexible duct. FIG. 4 is an enlarged cross-sectional view of the inner membrane body and the heat insulating layer of the flexible duct according to the second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a flexible duct 1 used as piping for air conditioning equipment in a building such as an office building. The flexible duct 1 is a lighter and more flexible air-conditioning pipe than an aluminum duct, and extends from an air conditioner or a ventilator (not shown) to an air-conditioning area. The flexible duct 1 includes a core material 11, an inner membrane body 12, a heat insulating layer 13, and an outer membrane body 14.

The core material 11 is comprised with the thin board | plate material which consists of metals, such as steel and iron, and is a spiral line shape. As shown in FIG. 3, the initial shape (shape before molding) of the core material 11 is flat in the width direction. The width W ₁₁ of the core material 11 in the initial shape is preferably about W ₁₁ = 4 mm to 10 mm, and the thickness is preferably about 0.4 mm to 0.6 mm. As shown in FIG. 2, the core material 11 is formed in a C-shaped cross section for fixing the inner membrane body 12.

  The intima body 12 is tubular. A gas flow path 19 is defined inside the inner membrane body 12. A gas to be transported such as air whose temperature is adjusted (cooling / heating) or humidity is adjusted or air to be ventilated is passed through the gas flow path 19. A core material 11 is wound along the peripheral surface of the inner membrane body 12. The inner membrane body 12 covers the inner peripheral side of the core material 11.

  As shown in FIGS. 1 and 2, a tubular heat insulating layer 13 surrounds the outer periphery of the core material 11 and the inner membrane body 12. The heat insulating layer 13 is made of glass wool. The thickness of the heat insulation layer 13 is preferably 25 mm to 100 mm, and more preferably 25 mm to 50 mm. A tubular outer membrane body 14 surrounds the outer periphery of the heat insulating layer 13. The outer film body 14 is configured, for example, by laminating a resin single layer such as polyethylene or a resin layer such as polyethylene terephthalate and a metal layer such as aluminum. The thickness of the outer membrane body 14 is preferably 0.04 mm to 0.1 mm, and more preferably 0.04 mm to 0.08 mm.

The inner membrane body 12 will be further described in detail.
The inner membrane body 12 is composed of a resin band. That is, as shown in FIG. 3, the initial shape of the inner membrane body 12 is a strip shape having a certain width W <b> 12 (a dimension in the width direction orthogonal to the extending direction) and extending long. The width W12 is preferably W12 = 30 mm to 70 mm, and more preferably W12 = 40 mm to 60 mm. The strip-shaped inner membrane body 12 is wound in a spiral tube shape, and edges 12e and 12f facing each other with a pitch deviation from each other are fastened by the core member 11 from the outer peripheral side. Thus, the inner membrane body 12 is stretched in the gap 11e between the helical pitches of the core material 11.

  The resin constituting the inner membrane body 12 has a shape-retaining property capable of independently holding a spiral tubular state or a substantially flat state in the width direction. Here, “having a shape retaining property capable of independently holding the spiral tubular state” means that even when the inner membrane body 12 is released from the core material 11, the spirally wound state is naturally retained. It means that it will not be in any state such as folded or straightened unless force is applied from the outside. In addition, “having a shape-retaining property capable of independently holding a substantially flat state in the width direction” means, for example, that the inner membrane body 12 is bent in a round shape in the width direction so that both end edges are attached to each other. When it is later released, it means that it returns to a substantially flat state in the original width direction by the elastic restoring force of the intima body 12 itself. It can be said that it is “substantially flat” if the angle formed by both end portions in the width direction of the inner membrane body 12 after returning is 120 ° to 180 °, preferably 150 ° to 180 °.

Specifically, the inner membrane body 12 is composed of a biaxially stretched film containing polyethylene terephthalate (hereinafter referred to as “PET”) as a main component.
The thickness of the PET is preferably about 20 μm to 30 μm, more preferably about 25 μm.
Moisture permeability of the PET (conforming to JIS K7129) is preferably about ^{15g / m 2 · day~30g / m} 2 · day, more preferably about 23g ^/ m 2 · day.
Oxygen permeability of the PET (conforming to JIS K7126) is preferably 2 · MPa · about ^{day 500mL / m 2 · MPa ·} day~700mL / m, more preferably at 620mL ^/ m 2 · MPa · day about is there.
The longitudinal tensile fracture strength (based on JIS K7127) of the PET is preferably about 180 MPa to 280 MPa, more preferably about 230 MPa.
The longitudinal direction refers to a direction parallel to the machine traveling direction when the intima body 12 is manufactured (the extending direction of the intima body 12).
The transverse tensile fracture strength (based on JIS K7127) of the PET is preferably about 190 MPa to 290 MPa, more preferably about 240 MPa.
The horizontal direction refers to a direction (width direction of the inner membrane body 12) orthogonal to the vertical direction.
The longitudinal tensile fracture elongation (based on JIS K7127) of the PET is preferably about 80% to 120%, more preferably about 100%.
The transverse tensile fracture elongation (based on JIS K7127) of the PET is preferably about 70% to 110%, more preferably about 90%.
The longitudinal tensile elastic modulus (based on JIS K7127) of the PET is preferably about 3500 MPa to 4400 MPa, more preferably about 3920 MPa.
The lateral tensile elastic modulus (based on JIS K7127) of the PET is preferably about 3600 MPa to 4500 MPa, more preferably about 4020 MPa.

The manufacturing method of the flexible duct 1 is demonstrated centering on the process of shape | molding the core material 11 and the inner-film body 12 in helical shape.
As shown in FIG. 3, the core material 11 and the inner membrane body 12 are automatically molded by a dedicated automatic molding machine. As schematically shown by arrows in the figure, the automatic molding machine includes a bending action part 2a and a fastening action part 2b. The bending action part 2a temporarily bends the inner membrane body 12 in the width direction. At this time, the central portion in the width direction of the intima 12 is preferably bent so as to draw a loop, and preferably not creased. Subsequently, the core member 11 is deformed (crimped) into a C-shaped cross section by the fastening action portion 2 b, so that the edges 12 e and 12 f of the inner membrane body 12 that are opposed to each other by one pitch are stopped by the core member 11. To wear. Before and after the fastening, the bending action part 2a is released from the intima body 12. Then, as shown by an arrow a in FIG. 3, the intima body 12 returns to a substantially flat state in the width direction by its own elastic restoring force. Thereby, the inner membrane body 12 can be easily and reliably formed into a tubular shape. A heat insulating layer 13 is put on the outer periphery of the inner film body 12 and the core material 11, and an outer film body 14 is put on the outer periphery of the heat insulating layer 13. In this way, the flexible duct 1 is created.

According to the flexible duct 1, since the inner membrane body 12 is made of a PET resin having shape retention, the inner membrane body 12 bears the shape retention strength of the flexible duct 1 in cooperation with the core material 11. be able to. Alternatively, the inner membrane body 12 can complement the strength of the core material 11. Thus, the flexible duct 1 can be reliably held in a tubular shape (annular section), and the required strength of the core material 11 can be reduced. Therefore, the core material 11 can be thinned, or the helical pitch (width of the inter-spiral pitch gap 11e) can be increased.
Further, it is possible to sufficiently secure the supporting force of the inner membrane body 12 with respect to the heat insulating layer 13.

As shown by a two-dot chain line in FIG. 2, when a portion 1 e corresponding to the inter-spiral pitch gap 11 e of the core material 11 in the flexible duct 1 receives an external force F from the side, the inner membrane body with respect to the external force F 12 can sufficiently exert the drag, and the portion 1e can be prevented from being recessed so much. Further, when the external force F is released, the portion 1e can be returned to the original cross-sectional shape by the elastic restoring force of the inner membrane body 12.
When the flexible duct 1 receives a force in the axial direction (longitudinal direction), when the force in the axial direction is released, in addition to the spring force of the core material 11, the elastic restoring force of the intima body 12 Thus, the flexible duct 1 can be reliably returned to the original length.

The inner membrane body 12 made of PET resin can attenuate the sound transmitted through the gas flow path 19 and ensure the soundproofing property of the flexible duct 1.
Further, since the inner membrane body 12 made of PET resin has low moisture permeability, when the transported gas flowing through the gas flow path 19 is humidified, the humidity can be maintained and the moisture retention of the flexible duct 1 is ensured. it can. In other words, it is possible to prevent moisture in the transported gas from passing through the inner film body 12 and being absorbed by the heat insulating layer 13. Therefore, it is possible to prevent the heat insulation layer 13 from generating odor and mold.
In addition, since the inner membrane body 12 made of PET resin has heat retaining properties, the temperature of the transported gas flowing through the gas flow path 19 can be maintained, and the heat retaining properties of the flexible duct 1 can be ensured.
Since the inner membrane body 12 covers the core material 11 from the gas flow path 19 side, the core material 11 can be prevented from being directly exposed to the gas flow path 19. Thereby, it is possible to prevent the transported gas flowing through the gas flow path 19 from coming into contact with the core material 11. Thereby, the corrosion of the core material 11 can be suppressed or prevented.
Further, by covering the inner peripheral surface of the heat insulating layer 13 with the inner film body 12, it is possible to prevent the glass wool small pieces constituting the heat insulating layer 13 from being scattered in the gas flow path 19.

Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to the drawings and the description thereof is omitted for the same configurations as those of the above-described embodiments.
FIG. 4 shows a second embodiment of the present invention. The inner membrane body 12 of the second embodiment is a laminated body in which a first layer 12a and a second layer 12b are laminated (laminated). The first layer 12 a faces the gas flow path 19, and the second layer 12 b faces the heat insulating layer 13.

The first layer 12a is made of PET. Thereby, the moisture retention property and heat retention property of the to-be-transported gas which flows through the gas flow path 19 can be improved. The second layer 12b is made of polyethylene (PE).
The thickness of the first layer 12a made of PET is preferably about 10 μm to 40 μm, more preferably about 12 μm to 30 μm. The thickness of the second layer 12b made of PE is preferably about 10 μm to 40 μm, more preferably about 12 μm to 30 μm.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the second embodiment, the first layer 12a facing the gas flow path 19 may be composed of PE, and the second layer 12b facing the heat insulating layer 13 may be composed of PET.
The first layer 12a may be made of nylon, and the second layer 12b may be made of polypropylene (PP). Alternatively, the first layer 12a may be made of PP and the second layer 12b may be made of nylon.
Further, the material of the intima body 12 may be a resin having a shape retaining property capable of autonomously holding a spiral tubular state or a substantially flat state in the width direction, and is made of a resin other than the above. Alternatively, it may have a laminated structure of PET and PP.
The inner film body 12 may have a laminated structure of three or more layers.

Examples will be described. However, the present invention is not limited to the following examples.
While using a steel strip as the core material 11 and using a strip made of PET as the intima body 12, the elastic restoring force of the intima body 12 was examined.
The width W ₁₁ of the core material 11 was W ₁₁ = 5 mm.
The thickness of the core material 11 was 0.5 μm.
The width W ₁₂ of the inner membrane body 12 was W ₁₂ = 55 mm.
The thickness of the inner membrane body 12 was 25 μm.
Furthermore, the physical properties of PET constituting the inner membrane body 12 were as follows.
Moisture permeability (conforms to JIS K7129) ... 23 g / m ² · day
Oxygen permeability (according to JIS K7126) ... 620 mL / m ² · MPa · day
Longitudinal tensile fracture strength (based on JIS K7127) ... 230 MPa
Transverse tensile fracture strength (conforming to JIS K7127) ... 240 MPa
Longitudinal tensile elongation at break (conforming to JIS K7127) ... 100%
Transverse tensile elongation at break (conforming to JIS K7127) ... 90%
Longitudinal tensile elastic modulus (based on JIS K7127) ... 3920 MPa
Transverse tensile modulus (based on JIS K7127) ... 4020 MPa

  As shown in FIG. 3, this intima body 12 is incorporated in a dedicated automatic molding machine, bent by a bending action part 2 a so as to draw a loop in the width direction, and substantially aligned at both ends in the width direction, The edges 12e and 12f facing each other with a pitch deviation from each other were fixed by the core material 11. The bending action part 2a was released from the intima body 12 before and after the fastening. Then, the inner membrane body 12 returned to a substantially flat state in the width direction elastically. As a result, the inner membrane body 12 could be reliably formed into a helical tube by an automatic molding machine.

  The present invention can be used, for example, as air conditioning piping in an office building.

DESCRIPTION OF SYMBOLS 1 Flexible duct 11 Core material 12 Inner membrane body 12e, 12f Edge 19 Gas flow path

Claims (4)

Endocardium of helical tubular defining a gas flow path inside, and a core of C-shaped cross section of the inner membrane body made spiral along the outer peripheral surface of the metal, one to each other in said film body In the flexible duct in which both edges facing each other with a pitch deviation are fixed by the core material,
The inner membrane body is made of a resin-made band having a shape-retaining strength capable of independently holding a spiral tubular state or a substantially flat state in the width direction, and the band forms a loop in the width direction. It has an elastic restoring force capable of returning to a substantially flat state in the width direction when it is released after being bent until both edges in the width direction stick to each other, and the inner film body wound spirally flexible duct, characterized in that the edges each other facing is fastened I by the crimping of the core material with one another fit inside the same direction and the directed radially outward of the flexible ducts the core .   The flexible duct according to claim 1, wherein the inner membrane body includes polyethylene terephthalate.   The flexible duct according to claim 1 or 2, wherein the inner membrane body is a laminate of polyethylene terephthalate and polyethylene.   The flexible duct according to any one of claims 1 to 3, wherein the inner membrane body is a laminate of nylon and polypropylene.

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