JP7689885B2 - Flexible Duct - Google Patents

Description

The present invention relates to a flexible duct for constructing piping paths for conditioned air in air conditioning equipment for buildings.

Conventional flexible ducts are generally made with a lining on the inner circumference of a spiral reinforcing material, with insulation and an outer skin on the outer circumference, and are non-flammable, and are manufactured in predetermined lengths. The reinforcing material has the function of maintaining the cross-sectional shape of the duct and not impairing the air flow path, and is formed by processing a metal or synthetic resin wire into a spiral shape. The lining forms the inner wall surface of the air flow path, and is made of nonwoven fabric or the like. The lining is made breathable, and sound is transmitted through the lining to the area of the insulation, thereby reducing sound in the area of the insulation. The outer skin is the outer surface material of the duct, and is made of a weather-resistant synthetic resin film or the like.

Conventional flexible ducts with insulation are packed in a compressed state from their natural length and delivered to the construction site in order to reduce their size during transportation, but the flexible duct itself is always in a state where it is trying to return to its natural length. For this reason, when the compressive force applied during packaging is released, the flexible duct expands until it returns to its natural length, and it is not able to maintain the contracted state it was in when packed. The natural length of a conventional flexible duct refers to the size in the longitudinal direction of the flexible duct when it is left stationary in a straight and horizontal state without any external force being applied to the flexible duct in the longitudinal direction. When a conventional flexible duct is in its natural length, the spiral reinforcing material that constitutes the flexible duct is in a state of being extended in the longitudinal direction.

When installing a conventional flexible duct, as shown in FIG. 9, a flexible duct 100 is suspended in the space between the building frame 101 and the ceiling 103 using suspension members 102 such as suspension bolts 102a and bands 102b provided at regular intervals on the building frame 101. However, if a duct longer than the required length is used, slack 100a may occur in the flexible duct 100 located between the two bands 102b, 102b. Such slack 100a occurs because the duct length is selected based on the building plan, taking into account the height difference when the duct is installed and a certain amount of extra length, so it does not completely match the actual required length, and a certain amount of error may occur in the duct length.

When slack 100a occurs in the flexible duct 100 shown in FIG. 9, unnecessary pressure loss occurs in the duct flow path within the slack 100a. This phenomenon occurs more significantly when the length of the flexible duct 100 located between the two bands 102b, 102b at the location where the flexible duct 100 is installed is longer than necessary.

To solve this problem, technology has been disclosed for keeping flexible ducts in a contracted state (see, for example, Patent Documents 1 and 2).

The flexible duct described in Patent Document 1 is a flexible duct for air conditioning that can be freely bent and expanded/contracted. It has two constraint points spaced apart in the axial direction of the duct body, and a bendable operator such as a string or wire connected to the duct body via these constraint points. The operator can be moved in the axial direction of the duct body relative to at least one of the two constraint points, and the duct body can be expanded/contracted by moving the operator.

The flexible duct described in Patent Document 2 is a flexible duct consisting of a core material formed into a coil shape, a heat insulating material arranged as an intermediate material around the outer periphery of the core material, and an outer periphery of the heat insulating material, and is characterized in that a bag body with a wire inside is attached to the outer periphery of the outer periphery of the outer periphery and/or between the core material and the heat insulating material in a predetermined number of positions in the longitudinal direction using adhesive tape, allowing the shape to be freely maintained.

JP 2001-201159 A JP 2010-261627 A

The flexible ducts described in Patent Documents 1 and 2 each have additional components to maintain the shape of the duct body, which makes the structure complex and raises concerns about rising costs due to the increased number of parts.

In addition, when constructing the flexible ducts described in Patent Documents 1 and 2, new tasks other than the actual duct installation work, such as handling strings and attaching wires, are required, which can cause construction delays.

The problem that this invention aims to solve is to provide a flexible duct that has a shape-retaining function, can prevent the duct from loosening after installation and the increase in duct pressure loss caused by the loosening, and can simplify duct installation work and standardize and consolidate duct lengths.

The flexible duct according to the present invention is a flexible duct having a structure in which a lining is attached to the inner circumference of a spiral-shaped reinforcing material, and the reinforcing material is a tension spring that urges the flexible duct to contract along the longitudinal direction when no longitudinal tensile force is applied to the flexible duct. Here, the "tension spring" is also called a "tension coil spring," and is a coil spring that generates an elastic restoring force (elastic contraction force) when subjected to a tensile force in the longitudinal direction (extension direction) of the spring.

With this configuration, the reinforcing material is kept in a contracted state when it is at its natural length and no tensile force is applied to it, so there is no extension phenomenon (the phenomenon in which the material expands to return to its natural length when no compressive force is applied) that occurs in conventional flexible ducts when the compressive force applied during packaging is released, and the duct can be stretched as much as necessary when installed.

In addition, the elastic restoring force of the reinforcing material keeps the excess portion of the duct in a contracted state, reducing slack when laying the duct and preventing increased pressure loss. Furthermore, the flexible duct itself has a shape-retaining function without the need for additional parts or work, improving workability. If the position of the air conditioner or air outlet needs to be changed at the construction site, this can be accommodated by simply extending or shortening the excess length.

The natural length of the flexible duct of the present invention refers to the size in the longitudinal direction of the flexible duct when the flexible duct is left stationary in a straight and horizontal state without applying any external force in the longitudinal direction. When the flexible duct of the present invention is in a natural length state, the spiral reinforcing material that constitutes the flexible duct is in a state of contraction in the longitudinal direction.

In this way, the flexible duct of the present invention can be adjusted to the duct length required for installation, so the number of different lengths can be reduced and the duct length can be standardized, making it easier to manage the manufacturing process and delivery. For example, currently flexible ducts are manufactured to a length of approximately 10 m in increments of 0.5 m, but if the duct length can be expanded and maintained within a range from the full length to approximately 1.5 to 2 times the full length, various duct lengths can be manufactured in increments of 1 m or 2 m to accommodate various installation conditions, and the number of different duct lengths can be reduced and the duct length can be standardized, which is advantageous in terms of both manufacturing and management.

The reinforcing material that constitutes the flexible duct can be a metal spring material or a synthetic resin spring material.

When the reinforcing material is a metal spring material, it can be manufactured in the same way as a conventional flexible duct, and can maintain high strength. Next, when the reinforcing material is a synthetic resin spring material, the means of joining with the lining can be welding or bonding, so manufacturing is easy and it is possible to reduce the weight compared to metal spring material.

Next, in the flexible duct, a heat insulating material and an outer skin can be attached to the outer periphery of the reinforcing material.

This configuration allows the flexible duct to have insulating properties while maintaining the aforementioned effects.

Next, in the flexible duct, the lining can be made of breathable nonwoven fabric.

With this configuration, sound passes through the nonwoven fabric into the area of the insulating material (glass wool) and is muted in the area of the insulating material (glass wool), thereby improving the quietness of the flexible duct.

The present invention provides a flexible duct that has a shape-retaining function, can prevent the duct from loosening after installation and the increase in duct pressure loss caused by the loosening, and can simplify duct installation work and standardize and consolidate duct lengths.

1 is a partially omitted side view showing a state of a natural length of a flexible duct according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, with some parts omitted. 3 is a partially omitted enlarged view of a region indicated by an arrow B in FIG. 2 . 2A and 2B are cross-sectional views with partial omissions showing the stretched and contracted states of a spiral reinforcing material that constitutes the flexible duct shown in FIG. 1, in which (a) shows the natural state and (b) shows the extended state. 2A and 2B are partially cutaway side views showing the flexible duct shown in FIG. 1 in an expanded or contracted state, in which FIG. 2A shows the natural state and FIG. 2B shows the expanded state. 2 is a partially omitted side view showing the installation process of the flexible duct shown in FIG. 1, showing the state before a tensile force is applied to the flexible duct. 2 is a partially omitted side view showing the installation process of the flexible duct shown in FIG. 1, showing the state in which the flexible duct is extended by application of a tensile force. FIG. 8 is a vertical cross-sectional view showing the flexible duct shown in FIG. 7, with some parts omitted. FIG. 1 is a partially omitted side view showing the installation state of a conventional flexible duct.

Below, flexible duct 1, an embodiment of the present invention, will be described with reference to Figures 1 to 8. First, the structure of flexible duct 1 will be described with reference to Figures 1 to 5.

As shown in Figures 1 to 3, the flexible duct 1 comprises a linear reinforcing material 10 having a spiral shape, an inner lining 11 attached to the inner circumference of the linear reinforcing material 10, an insulating material 12 attached to the outer circumference of the reinforcing material 10, and an outer skin 13 attached to the outer circumference of the insulating material 12. The reinforcing material 10 is a tension spring that urges the flexible duct 1 to contract along the longitudinal direction L when no tensile force is applied to the flexible duct 1 in the longitudinal direction L. The inner lining 11 is made of breathable nonwoven fabric, and the insulating material 12 is made of glass wool.

As shown in FIG. 4, the single reinforcing member 10 constituting the flexible duct 1 is a tension spring formed in a spiral shape using a metal spring material, and is also called a tension coil spring. As shown in FIG. 4(a), when the single reinforcing member 10 is left in a straight and horizontal state without being subjected to a tensile force P in its longitudinal direction L, its length S1 in its longitudinal direction (extension direction) L remains in its most contracted state. On the other hand, as shown in FIG. 4(b), when a tensile force P in its longitudinal direction (extension direction) L is applied to the reinforcing member 10, it extends to a length S2 corresponding to the magnitude of the tensile force P within the elastic limit, and is maintained in a state in which an elastic restoring force (elastic contraction force) is generated.

As shown in Fig. 5(a), when a tensile force P in the longitudinal direction L is not applied to the flexible duct 1 incorporating the reinforcing material 10 and the flexible duct 1 is left in a straight and horizontal state, the flexible duct 1 is biased by the reinforcing material 10 to contract along the longitudinal direction L, and the length F1 of the flexible duct 1 in the longitudinal direction (extension direction) L is kept in a contracted state (natural length state). On the other hand, as shown in Fig. 5(b), when a tensile force P in the longitudinal direction (extension direction) L is applied to the flexible duct 1, the flexible duct 1 is extended to a length F2 corresponding to the magnitude of the tensile force P within the elastic limit of the reinforcing material 10, and is kept in a state in which an elastic restoring force (elastic contraction force) is generated by the reinforcing material 10.

In this way, in the flexible duct 1, the reinforcing material 10 is kept in a contracted state (natural length state shown in Figure 5 (a)) when no tensile force P is applied in the longitudinal direction L, so that the stretching phenomenon (the phenomenon of stretching to return to the natural length state when no compressive force is applied) that occurs in conventional flexible ducts when the compressive force in the packed state is released does not occur, and therefore, when the duct is installed, it can be stretched as much as necessary, as shown in Figure 5 (b).

In an actual flexible duct 1, as shown in FIG. 5(a), the lining 11, the insulation 12, and the outer skin 13 are added to the reinforcing material 10, so the reinforcing material 10 in the state shown in FIG. 5(a) does not shrink to the state in which it would shrink without an external force like the reinforcing material 10 alone shown in FIG. 4(a), but is slightly expanded from the state shown in FIG. 4(a) due to the thickness of the insulation 12, etc. As a result, the reinforcing material 10 biases the lining 11, the insulation 12, and the outer skin 13 to shrink along the longitudinal direction L.

Next, a method for constructing the flexible duct 1 will be described with reference to Figures 6 to 8. Note that the construction method shown in Figures 6 to 8 is an example and is not limited to this.

When constructing the flexible duct 1, as shown in FIG. 6, the flexible duct 1 is suspended in the space between the building structure 2 and the ceiling 5 using suspension members 3 such as suspension bolts 3a and bands 3b provided at predetermined intervals on the building structure 2. In this embodiment, the base end 1b of the flexible duct 1 is connected to the chamber 4, and the flexible duct 1 is suspended and held near the center of the longitudinal direction L by the suspension members 3 on the building structure 2.

In the state shown in Figure 6, no tensile force P is applied to the flexible duct 1 in the longitudinal direction L, so the reinforcing material 10 (see Figure 5) urges it to contract along the longitudinal direction L, and the length in the longitudinal direction (extension direction) L remains contracted.

After that, in order to extend the length of the flexible duct 1 in the state shown in Figure 6 according to the conditions at the construction site, when a tensile force P is applied to the tip 1a of the flexible duct 1 in its longitudinal direction (extension direction) L, the flexible duct 1 will extend to a length corresponding to the magnitude of the tensile force P, as shown in Figures 7 and 8.

When the flexible duct 1 has been extended to a predetermined length, a hanging member 3 is attached to the tip end side (opposite the base end 1b) of the flexible duct 1 and it is hung from the building structure 2. When a tensile force P is applied in the longitudinal direction (extension direction) L, the flexible duct 1 is maintained in a state in which an elastic restoring force (elastic contraction force) is generated by the reinforcing member 10.

If it is subsequently necessary to further extend the flexible duct 1 to connect it to equipment such as an air conditioner or an air outlet (not shown), as described above, the tensile force P in the longitudinal direction (extension direction) L of the flexible duct 1 near the tip 1a (see Figure 6) can be increased to extend it to the required length within the elastic limit of the reinforcing material 10, thereby connecting the flexible duct 1 to equipment such as an air conditioner or an air outlet.

As mentioned above, in the flexible duct 1, when the duct is at its natural length and no tensile force P is applied in the longitudinal direction, the reinforcing material 10 is kept in a contracted state (as shown in FIG. 5(a)). This means that the stretching phenomenon that occurs in conventional flexible ducts when the compressive force applied during packaging is released (the phenomenon in which the duct stretches to return to its natural length (the length when no compressive force is applied)) does not occur, and when the duct is installed, it can be stretched as much as necessary, as shown in FIG. 7 and FIG. 8.

In addition, the excess portion of the flexible duct 1 during construction is kept in a contracted state by the elastic restoring force of the reinforcing material 10, reducing slack when laying the duct and preventing an increase in pressure loss. Furthermore, the flexible duct 1 itself has a shape retention function (contraction function), making it easy to construct. Therefore, when the position of the air conditioner or air outlet needs to be changed at the construction site, the excess length of the flexible duct 1 can be easily extended or contracted.

In this way, the flexible duct 1 can be adjusted to the duct length required for installation, so the number of different lengths can be reduced and the duct length can be standardized, making it easier to manage the manufacturing process and delivery of the flexible duct 1. For example, currently flexible ducts are manufactured to a length of approximately 10 m in increments of 0.5 m, but if the length of the flexible duct 1 can be expanded and contracted within a range of approximately 1.5 to 2 times its total length, the number of different lengths of the flexible duct 1 can be manufactured in increments of 1 m or 2 m to accommodate installation conditions, so the number of different lengths can be reduced and the length of the flexible duct 1 can be standardized. Therefore, it becomes possible to select a flexible duct 1 of an appropriate length from the standardized flexible ducts 1 based on the design drawings of the building.

In this embodiment, the reinforcing material 10 constituting the flexible duct 1 is a metal spring material, so it can be manufactured in the same way as conventional flexible ducts and can maintain high strength. On the other hand, if the reinforcing material 10 is a synthetic resin spring material, the means for joining it to the lining 11 (see Figure 3) can be welding or bonding, so it is easy to manufacture and can be made lighter than a metal spring material.

As shown in FIG. 3, in the flexible duct 1, the insulating material 12 and the outer skin 13 are attached to the outer periphery of the reinforcing material 10, so that the flexible duct 1 can be made insulating while maintaining the above-mentioned effects.

Also, as shown in FIG. 3, if the lining 11 of the flexible duct 1 is made of breathable nonwoven fabric and the insulation 12 is made of glass wool, sound will pass through the nonwoven fabric into the area of the insulation 12 (glass wool) and be muffled in the area of the insulation 12 (glass wool), thereby improving the quietness of the flexible duct 1.

Note that the flexible duct 1 described based on Figures 1 to 8 is an example of a flexible duct according to the present invention, and the flexible duct according to the present invention is not limited to the flexible duct 1 described above.

The flexible duct of the present invention can be widely used in industrial fields such as the construction and building industries as part of the air conditioning equipment installed in various buildings.

REFERENCE SIGNS LIST 1 Flexible duct 1a Tip end 1b Base end 2 Building frame 3 Suspension member 3a Suspension bolt 3b Band 4 Chamber 5 Ceiling 10 Reinforcement material 11 Lining 12 Thermal insulation material 13 Outer skin F1, F2, S1, S2 Length L Longitudinal direction P Tensile force

Claims (3)

A flexible duct having a structure in which a lining is attached to the inner circumference of a spiral-shaped reinforcing material, the reinforcing material being a tension spring that urges the flexible duct to contract along the longitudinal direction when no longitudinal tensile force is applied to the flexible duct , and a heat insulating material and an outer skin are attached to the outer circumference of the reinforcing material . The flexible duct according to claim 1, wherein the reinforcing material is a metal spring material or a synthetic resin spring material. 3. The flexible duct according to claim 1 , wherein the lining is made of a breathable nonwoven fabric.

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