JPS6330174Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a synthetic resin flexible electrical conduit that has a corrugated synthetic resin inner tube and a smooth synthetic resin outer tube to provide flexibility.

[Conventional technology]

Figure 1 shows a synthetic resin flexible electrical conduit that has been proposed in the past.It is made of a material such as polyethylene or polypropylene and has a corrugated synthetic resin inner tube with repeated axial irregularities on both the inner and outer surfaces. 2 and a synthetic resin outer tube 4 which is made smooth inside and out by extrusion of a material such as vinyl chloride and coated so as to circumscribe the convex portion of the inner tube. It has flame retardant properties because it functions as a pipe sheath.

Such a synthetic resin flexible electric conduit is used for direct burying in concrete, and the electric wire is drawn into the internal space 1 of the inner tube 2 to function as a conduit.

[The problem that the invention attempts to solve]

However, such synthetic resin flexible conduit pipes have no function to detect damage to the outer and inner pipes during use (directly buried in concrete), and it is not known until the wires that have been drawn in are damaged. There was a tendency for the damage to spread further.

In addition, in the case of exposed piping, if a fire occurs and comes into contact with the flames, the wall thickness of the outer pipe is relatively small, so the fire can easily penetrate to the inner pipe, and once the fire penetrates the inner pipe and enters the inner pipe. If it did, there was a risk that the fire would spread through the flexible electrical conduit due to the chimney effect.

In view of the problems of the synthetic resin flexible conduit, the present invention has been developed to provide an improved synthetic resin flexible conduit that has improved flame resistance and also makes it possible to detect external damage before the wire being led is damaged. The purpose is to provide

[Means to solve the problem]

In order to achieve the above-mentioned object, in the present invention, as shown in FIG. Alternatively, a metal foil laminated plastic tape 7 is interposed between the peaks 6a of the inner tube 6 so as to have slack 7a at the valleys 6b.

〔Example〕

FIG. 2 shows an embodiment of a synthetic resin flexible conduit according to the present invention, with a corrugated synthetic resin inner tube 6, a smooth synthetic resin outer tube 8, and a conventional synthetic resin flexible conduit. However, an improvement has been made in that a metal tape or metal foil laminate plastic tape 7 is interposed between the inner tube 6 and the outer tube 8.

The metal tape or metal foil laminated plastic tape 7 is attached vertically to the outer periphery of the inner tube 6 before covering the outer tube 8 to cover the crest 6a of the inner tube 6.
and a slack 7a in the trough 6b between the peaks 6a in the inner tube 6.
The outer tube 8 is covered with the outer tube 8 and held down from above.

Since the metal tape or metal foil laminated plastic tape 7 has the slack 7a, it is not cut when the inner tube 6 and the outer tube 8 are bent when installed as a conduit, and is well suited to the bending. It bends compliantly and therefore remains sound after installation, without the loss of flexibility often associated with the use of metal.

When using metal foil laminated plastic tape, place the plastic tape on the inner tube 6 side and the metal foil on the smooth outer tube 8 side to prevent the metal foil from rubbing against the uneven surface of the inner tube. It is best to avoid wrinkles or damage caused by being rubbed.

[Effect of idea]

According to the synthetic resin flexible electrical conduit of the present invention constructed as described above, when directly buried in concrete, metal objects such as nails penetrate the outer pipe and the metal of the metal tape or metal foil laminated plastic tape is removed. If the foil is reached, an electrical closed circuit is formed through the concrete-nail-metal tape or metal foil. Therefore, it is possible to prevent damage to the electric wire and to minimize the damage.

In addition, in the case of exposed piping, even if the surface outer pipe is lost due to a fire, the flame-blocking effect of the interposed metal tape or metal foil can prevent the spread of fire to the inner pipe and electric wires, preventing disasters. The top is also extremely advantageous.

Metal tapes or metal foil laminated plastic tapes that function as external injury detection and flame shielding have slack in the troughs between the ridges of the corrugated outer tube, so they are less susceptible to damage during installation. There is no risk of the waves breaking when bent, and there is no decrease in flexibility, which is required for this type of electrical conduit, so it remains as a sound metal layer until after the facility is installed, ensuring the detection of external damage and flame shielding. The present invention provides a synthetic resin flexible electrical conduit that is useful as a synthetic resin flexible conduit.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view showing an example of a conventional flexible synthetic resin conduit, and FIG. 2 is an explanatory longitudinal cross-sectional view showing one embodiment of the flexible synthetic resin conduit according to the present invention. In the figure, 5 is an internal space, 6 is a corrugated synthetic resin inner tube, 6a is a peak, 6b is a valley, 7 is a metal tape or metal foil laminated plastic tape,
7a is a slack tube, and 8 is a smooth synthetic resin outer tube.

Claims (1)

[Scope of utility model registration request] A metal tape or metal foil laminated plastic tape is placed between the corrugated synthetic resin inner tube, which has irregularities on both the inner and outer surfaces, and the smooth inner and outer synthetic resin outer tube, to prevent slack in the valleys between the peaks of the inner tube. A synthetic resin flexible electrical conduit characterized in that it is interposed so as to hold the conduit.