GB2556292A - Cable theft prevention method, cable theft prevention structure, and trough wiring - Google Patents

Abstract

A cable 11 is installed in a trough body 3. An elastic member 7, which is a cable-pressing member, is provided between a trough lid 5 and the cable 11. One end surface (upper surface) of the elastic member 7 contacts the reverse surface of the trough lid 5. The other end surface (lower surface) of the elastic member 7 is in contact with the upper surface of the cable 11. The elastic member 7 is pressed from the reverse surface of the trough lid 5. As a result, the elastic member 7 presses the cable 11 while elastically deforming. Having the elastic member 7 press the cable 11 causes the elastic member 7 to act as a resistance when the cable 11 is pulled out from one end, making it possible to resist the tensile force acting on the cable 11. Using a foamed plastic body for the elastic member makes it possible to easily secure the trough lid and adjust the pressing force

Description

(56) Documents Cited:

WO 2011/104863 A1 JP 2012122323 A JPH0716531 JP H0670438

H02G1/06 (2006.01)

JP 2014011881 A JP 2009014147 A (86) International Application Data:

PCT/JP2016/069702 Ja 01.07.2016 (87) International Publication Data:

WO2017/026201 Ja 16.02.2017 (71) Applicant(s):

Furukawa Electric Co Ltd

2-3 Marunouchi 2-chome, Chiyoda-ku,

Tokyo 100-8322, Japan (72) Inventor(s):

Naoto Wada Satoshi Kozawa Yousuke Miura Takuzo Hagiwara Rota Fausto (74) Agent and/or Address for Service:

Beck Greener

Fulwood House, 12 Fulwood Place, LONDON, WC1V6HR, United Kingdom (58) Field of Search: INT CL H02G (54) Title of the Invention: Cable theft prevention method, cable theft prevention structure, and trough wiring Abstract Title: Cable theft prevention method, cable theft prevention structure, and trough wiring (57) A cable 11 is installed in a trough body 3. An elastic member 7, which is a cable-pressing member, is provided between a trough lid 5 and the cable 11. One end surface (upper surface) of the elastic member 7 contacts the reverse surface of the trough lid 5. The other end surface (lower surface) of the elastic member 7 is in contact with the upper surface of the cable 11. The elastic member 7 is pressed from the reverse surface of the trough lid 5. As a result, the elastic member 7 presses the cable 11 while elastically deforming. Having the elastic member 7 press the cable 11 causes the elastic member 7 to act as a resistance when the cable 11 is pulled out from one end, making it possible to resist the tensile force acting on the cable 11. Using a foamed plastic body for the elastic member makes it possible to easily secure the trough lid and adjust the pressing force

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CABLE THEFT PREVENTION METHOD, CABLE THEFT PREVENTION STRUCTURE, AND TROUGH LINE

TECHNICAL FIELD OF THE INVENTION [0001]

This invention relates to a theft prevention method for cables being accommodated inside troughs, a cable theft prevention structure, and trough line.

BACKGROUND OF THE INVENTION [0002]

Troughs, which are made of resin for example, are conventionally laid along railway tracks and roadsides to hold various types of cables within interior thereof. Such a trough usually has a fixed lid that prevents foreign substances from entering therein, mischief on the cables, and the hke. A fixing band or the like is used to fix such a lid (Patent Document 1 for example).

[0003]

Alternatively, a fixing structure using fixing metal fittings, which are attached to a trough body, with bolts or the hke to firmly fix the trough lid to the trough body has been proposed. For example, Patent Document 2 discloses a fixing structure in which fixing metal fittings are attached to both sides of a trough, and bolts are inserted from upper part of the closed trough lid so as to fix the bolts to the nut portions of the fixing member to fix the trough lid to the trough.

RELATED ART

PATENT DOCUMENTS [0004] [Patent Document l] Japanese Unexamined Patent Application Publication No.HlO-164723 (JP-A- H10-164723) [Patent Document 2] International Patent Publication No. W02011/104863

SUMMARY OF THE INVENTION (PROBLEMS TO BE SOLVED BY THE INVENTION) [0005]

On the other hand, theft of cables inside troughs has been an issue in recent years. One way of stealing a cable is, for example, to take out several lids at two places in a laying direction of the troughs with a predetermined interval

I therebetween, cut the cable at each part, and then pull out the cable from one side. The cable is pulled out and then taken away in this way.

[0006]

For this reason, both above mentioned Patent Documents 1 and 2 propose a countermeasure such as use of a fixing tool that cannot be unfixed without using a special tool so as to make it difficult to open the lids. However, as mentioned above, when stealing the cable, it is unnecessary to take out all the lids covering the entire length of the cable to be pulled out. And, since it is necessary to take out only part of the lids, a few improvements on the fixing method of the lids have never been enough to prevent the cable theft.

[0007]

The present invention was made in view of such problems. Its object is to provide a cable theft prevention method, a cable theft prevention structure, and trough line, which make stealing of cables difficult.

(MEANS FOR SOLVING PROBLEMS) [0008]

To achieve the above object, a first invention is a cable theft prevention method in which an elastic member is disposed between a cable, which is laid inside a trough body, and a trough lid covering an upper part of the trough body, a reverse surface of the trough lid is in contact with the elastic member, and the elastic member is pressed by the reverse surface of the trough lid so that the elastic member presses the cable.

[0009]

Although a resin sheet, a rubber member (a rubber sheet or rubber in a block shape), or a plastic foam may be used as the elastic member, the elastic member is preferably made of a plastic foam from the perspective of cost, workability, pressing force adjustment, and the like.

[0010]

It is preferable that the plastic foam has two end faces! one of the end faces of the plastic foam is in contact with the reverse surface of the trough lid, and the other end face of the plastic foam presses the cable.

[0011]

A plurality of reinforcing ribs may be formed on the reverse surface of the trough lid! the plastic foam may be inserted between the reinforcing ribs on the reverse surface of the trough lid to be fixed and pressed, or the plastic foam may be brought into contact with tip ends of the reinforcing ribs to be pressed.

[0012]

The reinforcing ribs may be parallel to a longitudinal direction of the trough lid and/or may be parallel to a width direction of the trough lid. When the reinforcing ribs press the elastic member as mentioned above, at least both reinforcing libs that are parallel to the longitudinal direction of the trough lid and the reinforcing ribs that are parallel to the width direction of the trough lid may press the elastic member.

[0013]

The plastic foam is in an approximately rectangular parallelepiped shape and three sides of the elastic member intersecting with each other at right angles may vary in length. If such an elastic member having three sides in different lengths is used, it is possible to choose and arrange one side of the elastic member in a direction in which pressing force is applied, depending on a distance between the cable laid inside the trough and the reverse surface of the trough lid or the ends of the reinforcing ribs.

[0014]

A plurality of the cables are disposed inside the trough body and the plurality of the cables may be bundled with a bundling member. If the cables are bundled in this way, the cables at the top layer or the largest of the cables are pressed and thus all the cables disposed in the trough can be fixed.

[0015]

The plastic foam may be a laminated structure body formed of a plurality of layers of plastic foams. Making the laminated structure body made of a plurality of elastic bodies in this way allows to change the number of laminated layers of the elastic body disposed inside the trough and facilitates height adjustment of the laminated structure.

[0016]

The laminated structure body may include at least either of a hard plastic foam or a soft plastic foam. For example, either a combination of hard plastic foams, a combination of soft plastic foams or a combination of hard and soft plastic foams may be used. Also, it is possible to make the strength of hard plastic foams used, or the strength of soft plastic foams used, different from one another.

[0017]

The laminated structure body may include a soft plastic foam laminated on a surface layer of a hard plastic foam! the soft plastic foam may be in contact with the cable and the hard plastic foam may be in contact with the trough lid side.

[0018]

The laminated structure body may include layers that are bonded each other with an adhesive agent or a tacky agent. For the plastic foam used for the laminated structure body, bonding agents such as epoxy adhesive, urethane-based adhesive, polyester-based adhesive, or emulsion-type adhesive may be used depending on the resin material used. Alternatively, a hot melt type can be used. Also, for a rubber-based plastic foam, rubber-based solvent-type adhesive or emulsion-type adhesive may be used. Here, as a bonding agent for the laminated structure body, it is possible to use an adhesive agent that can bond the layers together but still allows the laminated layers to be separated from each other.

[0019]

Preferably, the plastic foam has elastic rebound force between 15 kPa and 50 kPa at the time of 25 % compression deformation. The elastic rebound force of a plastic foam at the time of 25 % compression deformation in the present invention can be used as the same meaning as the force with the same strength but in an opposite direction as the compression stress at the time of 25 % compression and deformation of the plastic foam. In the present invention, the compression stress required to deform 25 % of the plastic foam is not an issue. Instead, the elastic rebound force of the plastic foam exerted on the cable and the change in a contacting area between the plastic foam and the cable are the issues. Thus, basically, the expression “elastic rebound force at the time of 25 % compression deformation” will be mainly used hereinafter.

[0020]

The elastic member may be adhered to the trough lid. This can fix the elastic member to the trough lid and make the elastic member unlikely to be shifted when pulling force is applied to the cable inside the trough.

[0021]

The elastic member may be formed of any one of plastic foams or rubber foam bodies selected from a group consisting of polyethylene resin, polypropylene resin, polystyrene resin, polyurethane resin, PVC resin, EVA resin, EPDM rubber, nitrile rubber, acrylic rubber, and chloroprene rubber. It is preferable to use an all-purpose polyolefin plastic foam such as polyethylene resin or polypropylene resin.

[0022]

The trough lid may be fixed to the trough body by using a trough lid fixing member and the trough lid fixing member may press the trough lid so that the elastic member is pressed to the cable.

[0023]

According to the first invention, since the elastic member presses the cable, contact between the cable and the elastic member can increase resistance against pulling out of the cable. As a result, pulling the cable out of the trough in one direction becomes difficult. Thus, theft of the cable can be prevented.

[0024]

Also, if the elastic member is a plastic foam, the elastic member is light and easy to handle. Also, deformation thereof can be within a range appropriate for closing the trough lid so a relatively large amount of deformation can be obtained and a sufficient contacting area between the elastic member and the cable can be secured.

[0025]

Also, upper and lower surfaces of the plastic foam as the elastic member are made into contact with the reverse surface of the trough lid and the cable so that the trough lid presses the plastic foam and the cable can be pressed from above with certainty.

[0026]

Also, if the plastic foam as the elastic member is inserted between reinforcing ribs on the reverse surface of the trough lid to be fixed, the reinforcing ribs serve as both reinforcement for the trough lid and a fixing means for the plastic foam. Also, using the reinforcing ribs facilitates fixing of the plastic foam as the elastic member to the trough lid.

[0027]

In particular, since the reinforcing ribs are parallel to the longitudinal direction of the trough lid and/or parallel to the width direction of the trough lid, the plastic foam, which is the elastic member in an approximately rectangular parallelepiped shape, can be easily fixed between the reinforcing ribs. Also, depending on the size of the plastic foam or the arrangement of the ribs of the trough lid, the tip ends of the reinforcing ribs may be brought into contact with the surface of the plastic foam and the tip ends of the reinforcing ribs can press the plastic foam.

[0028]

Here, when comparing the case in which the plastic foam as the elastic member is inserted between the reinforcing ribs to be fixed and pressed and the case in which tip ends of the reinforcing ribs are in contact with the surface of the plastic foam and the tip ends of the reinforcing ribs press the plastic foam, taking uniformity of pressing force into consideration, it is preferable to insert the plastic foam between the reinforcing ribs to be fixed and to press the plastic foam.

[0029]

Also, if the plastic foam as the elastic member is in an approximately rectangular parallelepiped shape and three sides of the elastic member intersecting with each other at right angles vary in length, protrusion amount of the elastic member from the reverse surface of the trough lid can be easily changed by changing the fixing direction of the elastic member. Thus, the same plastic foam can be used for various numbers of laying cables inside the trough body and a plurality of sizes of the trough.

[0030]

Also, when a plurality of cables are disposed inside the trough body, the plurality of the cables can be bundled together with a bundling member so as to prevent shifting or the like of the cables. Accordingly, this can prevent a situation in which the plastic foam as the elastic member is unable to maintain the pressing force to the cables due to shifting of the cables. This also can prevent cables that are not in contact with the elastic member, or cables with weak pressing force from the elastic member, from being pulled out easily. When the plurality of the cables are bundled with the bundling member in this way, it is required to pull out all the cables at once, and thus pulling out force for not only the pressing force exerted by the elastic member onto the cables but also an addition of self-weight of all the cables is required so it is impossible to pull out the cables easily.

[0031]

Also, the plastic foam as the elastic member may be in a laminated structure formed of a plurality of layers of plastic foams. For example, the laminated structure may be formed by laminating only hard plastic foams. In this case, the thickness of the elastic member can be changed easily by changing the number of laminated layers.

[0032]

Alternatively, if the laminated structure includes hard plastic foams and soft plastic foams, the thickness or the number of layers of the plastic foams can be adjusted so as to obtain pressing force that is appropriate for pressing the cables. For example, contacting a soft plastic foam having larger deformation capacity with the cables can increase the contacting area between the plastic foam and the cables so that the whole cables can be pressed. Also, contacting a hard plastic foam with the reverse surface of the trough lid can transfer the pressing force from the trough lid to the cables with more certainty.

[0033]

Also, if layers in the laminated structure are joined each other using an adhesive or tacky agent, the thickness of the laminated structure can be easily adjusted at the site according to the accommodation capacity of the cables inside the trough or the trough size.

[0034]

Also, if the elastic member is adhered to the trough lid, the elastic member can be fixed to the trough lid with more certainty.

[0035]

Also, it is preferable to press the cable if the elastic member is formed of any one of the following plastic foams: polyethylene resin, polyurethane resin, polystyrene resin, polypropylene resin, PVC (polyvinyl chloride) resin, EVA (ethylene-vinyl acetate) resin, EPDM (ethylene - propylene diene methylene linkage) rubber, nitrile rubber, acrylic rubber, and chloroprene rubber.

[0036]

Also, if a trough lid fixing member is used to fix the trough lid to the trough body, the trough lid fixing member presses the trough lid so that the elastic member can press the cables with more certainty.

[0037]

A second invention is a cable theft prevention structure including a trough, a trough lid that covers an upper part of the trough body and is fixed to the trough body, a cable that is laid inside the trough body, a cable pressing member that presses the cable, and a pressing force applying member that applies pressing force to the cable pressing member. The cable pressing member is disposed between the cable and the trough lid and the cable pressing member is an elastic member that is in contact with a reverse surface of the trough lid and the cable. The pressing force applying member presses the trough lid so that the cable pressing member is pressed to the cable through the trough lid.

[0038]

The pressing force applying member is a trough lid fixing member that fixes the trough lid to the trough body, and the trough lid fixing member may be either a fixing bolt, a fixing buckle, or a fixing band.

[0039]

A third invention is trough line including a plurality of the trough bodies and the trough lids that are joined together, in which a plurality of the cable theft prevention structures according to the second invention are provided at a plurality of locations. The number of such cable theft prevention structures is determined according to a design of pulling out force per predetermined length of the cable.

[0040]

According to the second and third inventions, a cable theft prevention structure and trough line in which pulling out of cables is difficult can be obtained.

(EFFECTS OF THE INVENTION) [0041]

The present invention can provide a cable theft prevention method, a cable theft prevention structure, and trough line, which make stealing of cables difficult.

BRIEF DESCRIPTION OF DRAWINGS [0042]

FIG. 1 is an exploded perspective view showing a cable theft prevention structure 1.

FIG. 2 is an assembled perspective view showing the cable theft prevention structure 1.

FIG. 3 is a cross sectional view of the cable theft prevention structure 1.

FIG. 4 (a) is a perspective view showing a trough lid fixing member 9a.

FIG. 4 (b) is a cross sectional view of a cable theft prevention structure Id.

FIG. 5 is a cross sectional view of a cable theft prevention structure le.

FIG. 6 (a) is a cross sectional view of the cable theft prevention structure 1 without using a bundling member 12.

FIG. 6 (b) is a cross sectional view of the cable theft prevention structure 1 without using the bundling member 12.

FIG. 7 is a cross sectional view of the cable theft prevention structure 1 using a bundling member 12.

FIG. 8 is a perspective view showing an elastic member 7.

FIG. 9 is a reverse surface view of a trough lid 5.

FIG. 10 is a reverse surface view of the trough lid 5 in another embodiment.

FIG. 11 is a reverse surface view of the trough lid 5 in another embodiment.

FIG. 12 illustrates trough line 30.

FIG. 13 (a) illustrates an elastic member 7a.

FIG. 13 (b) illustrates the elastic member 7a in a state in which a part of elastic bodies 25 is removed.

FIG. 14 (a) is a cross sectional view of a cable theft prevention structure lb.

FIG. 14 (b) is a cross sectional view of the cable theft prevention structure lb.

FIG. 15 illustrates an elastic member 7b.

FIG. 16 is a cross sectional view of a cable theft prevention structure lc.

FIG. 17 is a perspective view showing a method for testing a cable theft prevention structure.

FIG. 18 is a cross sectional view taken along J-J line in FIG. 17.

FIG. 19 illustrates the trough line 30.

DESCRIPTION OF SOME EMBODIMENTS [0043] (First Embodiment)

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of a cable theft prevention structure 1 according to the present invention, and FIG. 2 is an assembled perspective view of the cable theft prevention structure 1.

[0044]

A cable trough mainly includes a trough body 3 and a trough lid 5. The trough body 3 and the trough lid 5 are made of resin, for example, and molded by press molding or ejection molding. The trough body 3 and the trough lid 5 are approximately lm in length, for example.

[0045]

Fitting portions 13a and 13b are provided at both ends of the trough body 3 in a longitudinal direction thereof, respectively. The fitting portion 13a has a dent on an inner surface side of the trough body 3 whereas the fitting portion 13b has a protrusion corresponding to the dent on an outer surface side of the trough body 3. Thus, the trough bodies 3 can be joined together by fitting the fitting portion 13a of one trough body 3 with the fitting portion 13b of the adjoining trough body 3.

[0046]

The trough lid 5 covers an upper part of the trough body 3. The trough lid 5 is fixed to the trough body 3 with a trough lid fixing member 9. The trough lid fixing member 9 is a metal-made fixing band. The trough lid fixing member 9 is formed by bending a plate-like metal plate to have a pair of leg portions formed at both ends of the plate that are bent at approximately right angles to the top plate. That is, the trough lid fixing member 9 is substantially in a reversed U-shape.

[0047]

Each end of the leg portions is bent to form a locking portion 21. A fixing portion 15 is formed on an outer side face of the trough body 3. With the trough lid 5 being disposed over the trough body 3, the trough lid fixing member 9 is attached onto the trough lid 5 from above and the locking portions 21 are hooked onto the fixing portions 15 on the trough body 3 so that the trough lid 5 is fixed to the trough body 3.

[0048]

A cable 11 is laid inside the trough body 3. For example, a plurality of the cables 11 (three cables in the illustrated example) may be accommodated in the trough body 3. Also, an elastic member 7, which is a cable pressing member, is provided between the trough lid 5 and the cables 11.

[0049]

FIG. 3 is a cross sectional view taken vertically to the longitudinal direction of the cable theft prevention structure 1. The elastic member 7 has two facing end faces and one of the end faces (an upper face) is in contact with a reverse surface of the trough lid 5. Also, the other end face of the elastic member 7 (a lower face) is in contact with upper surfaces of the cable 11. Here, the elastic member 7 is pressed by the reverse surface of the trough lid 5 (illustrated as an arrow A). As a result, the elastic member 7 presses the cables 11 while elastically deforming (illustrated as an arrow B). That is, a thickness of the elastic member 7 before elastic deformation is larger than a gap between the reverse surface of the trough lid 5 and the upper ends of the cables 11.

[0050]

As mentioned above, the trough lid 5 is fixed to the trough body 3 with the trough lid fixing member 9. Thus, the trough fixing member 9 presses the trough lid 5 so that the trough lid 5 does not lift up from the trough body 3 due to rebound force of the elastic member 7. Also, the trough lid fixing member 9 can ensure that the elastic member 7 is pressed to the cable 11 through the trough lid 5. That is, the trough lid fixing member 9 serves as a pressing-force applying member that applies pressing force to the elastic member 7.

[0051]

Since the elastic member 7 presses the cable 11 in this way, when the cable 11 is pulled out from one end, the pressing force due to the elastic member 7 generates friction force resisting against the pulling force exerted onto the cable 11. Thus, it is possible to prevent the cable 11 from being pulled out.

[0052]

Holes 17 and grooves 19 are provided on the trough lid 5 (see FIG. 1 and FIG. 2) and these can also be used to fix the trough lid 5. A pair of the grooves 19 are provided on an upper surface of the trough lid 5 in the proximity of both sides thereof. The grooves 19 are provided at parts corresponding to the fixing portions 15 on the trough body 3 when the trough lid 5 is closed.

[0053]

FIG. 4 (a) illustrates a trough lid fixing member 9a. The trough lid fixing member 9a includes a gripping member 27 and a buckle 29. That is, the trough lid fixing member 9a is a fixing buckle. The gripping member 27 includes upper and lower gripping portions that are formed approximately parallel to each other and can hold the fixing member 15 between thereof. The upper gripping portion of the gripping member 27 has a hole or a cutout provided therein (a cutout is provided in the illustrated example).

[0054]

As in a cable theft prevention structure Id shown in FIG. 4 (b), the upper and lower gripping portions of the gripping member 27 hold the fixing member 15 between thereof so that the gripping member 27 is fixed. In this state, the buckle 29 is turned up toward the trough lid 5 so that the buckle 29 fits into the groove 19 on the upper surface of the trough lid 5. Thus, the trough lid 5 can be fixed to the trough body 3.

[0055]

As above, the trough lid 5 can be fixed to the trough body 3 by using the trough lid fixing member 9a. Thus, the trough lid fixing member 9a can prevent the trough lid 5 from lifting up from the trough body 3. As a result, the trough lid 5 can be pressed onto the elastic member 7, which can then press the cable 11.

[0056]

Similarly, a hole 17 (see FIG. 1 and FIG. 2) can also be used to fix the trough lid 5 to the trough body 3. FIG. 5 shows a cable theft prevention structure le using a tough lid fixing member 9b. The hole 17 is a through hole provided at a part corresponding to the fixing portion 15 of the trough body 3. The trough lid fixing member 9b is a fixing bolt.

[0057]

A gripping member 27a is attached to both sides of the fixing portion 15 of the trough body 3. The gripping member 27a, like the gripping member 27, has upper and lower gripping portions that are formed approximately parallel to each other, and the upper and lower gripping portions hold the fixing member 15 between thereof to be fixed. A hole or a cutout is provided on the upper gripping portion of the gripping member 27a.

[0058]

A nut portion is provided on the lower gripping portion of the gripping member 27a. The nut portion is a cap nut, for example. When the gripping member 27a is attached to the fixing portion 15, the hole 17 of the trough lid 5, the hole or the cutout of the gripping member 27a, and the nut portion are positioned at a part corresponding to each other. That is, when the trough lid fixing member 9b is inserted through the hole 17, the trough lid fixing member 9b can be screwed into the nut portion through the hole or the cutout.

[0059]

Inserting the trough lid fixing portion 9b from the upper part of the hole 17 in this way can fix the trough lid 5 to the trough body 3. Thus, the trough lid fixing member 9b can prevent the trough lid 5 from lifting up from the trough body 3. As a result, the trough lid 5 can be pressed onto the elastic member 7, which can then press the cable 11. The hole 17 is a countersinking hole and a head of the trough lid fixing member 9b does not protrude above the trough lid 5.

[0060]

As above, if the trough lid 5 can be fixed to the trough body 3, the trough lid 5 can serve as a pressing force applying member that applies pressing force to the elastic member 7. Hereinafter, examples in which the trough lid fixing member 9 is used will be described.

[0061]

Here, FIG. 3 to FIG. 5 illustrate the examples in which the cables 11 having the same diameter are provided in parallel in one row. When a plurality of the cables 11 are disposed in one row inside the trough body 3 in this way, the relative positions of the cables 11 (the distances between the elastic member 7 and the cables 11) is unlikely to change. Thus, the elastic member 7 can press the cables 11 inside the trough body 3, being in contact with all of the cables 11.

[0062]

However, as shown in FIG. 6 (a), there is a case in which a plurality of the cables 11 are disposed in a plurality of rows and the lowest row of the cables 11 has a space in a width direction of the trough body 3. In such a case, when the trough lid 5 is closed and the elastic member 7 presses the cables 11 of the top row, the cables 11 may be dislocated as shown in FIG. 6 (b) (illustrated as an arrow C).

[0063]

When the cables 11 with various sizes are laid or layers of the cables 11 are laid in lamination, it is likely that the distance between the cables 11 and the elastic member 7 may change due to dislocation of part of the cables 11 that are disposed inside the trough body 3.

[0064]

In such cases, it is impossible to keep the elastic member 7 and the cables 11 in a contact state, and thus both are separated from one another, resulting in no pressing force exerted onto each other. Or, even if both can be kept in the contact state, the pressing force exerting to one another may fall. Consequently, the cable 11 that is not in contact with the elastic member 7 or pressed with weaker pressing force by the elastic member 7 may be pulled out easily.

[0065]

As a countermeasure, it is preferable in the present invention that the plurality of the cables 11 are bundled by a bundling member 12 (illustrated by the dotted line) as shown in FIG. 7. This can prevent the part of the cables 11 from being relatively dislocated from the other cables 11. Thus, the elastic member 7 can press the cables 11 stably. When a plurality of cables having various sizes are fixed by a bundling member, it is impossible to exert pressing force of the elastic member 7 to a cable having a small diameter. However, even in such a case, the small·diameter cable is unified with the rest of the cables by the bundling member so it is impossible to pull out only the small·diameter cable.

[0066]

Since the plurality of the cables 11 are bundled together by the bundling member as above, in addition to the pressing force from the elastic member 7, pulling tension for pulling all the cables 11 bundled by the bundling member 12 at the same time is required to steal the cable 11, which makes it harder to steal the cable 11. Thus, the cable 11 can be prevented from being easily pulled out.

[0067]

The number and the size of the cables 11 inside the trough body 3 vary according to the laying sections and the construction sites. Thus, it is necessary to adjust the required thickness of the elastic member 7 depending on the laying sections and the sites. That is, to press the cables 11 with appropriate pressing force, it is preferable to use the elastic member 7 of an appropriate size according to the size and number of the cables 11. That is, the size of the elastic member 7 is preferably changed according to the distance between the trough lid 5 and the upper surface of the cables 11.

[0068]

The elastic member 7 in the present embodiment is in an approximately rectangular parallelepiped shape as shown in FIG. 8. Also, the lengths of the three sides thereof (E, F, and G in the drawing) intersecting with each other at right angles are different from each other. Thus, with the same elastic member 7, changing the direction of the elastic member 7 can change a length of protrusion from the reverse surface of the trough lid 5. Thus, by changing the direction of the elastic member 7 disposed according to the size and number of the cables 11, appropriate pressing force can still be ensured with the same elastic member 7.

[0069]

The elastic member 7 may be an elastically deformable member, preferably made of resin material. For example, rubber or resin (rubber) foams are applicable. As a plastic foam, any one of the following plastic foams or rubber foams, or mixture thereof is preferable: polyethylene resin, polyurethane resin, polystyrene resin, polypropylene resin, PVC (polyvinyl chloride) resin, EVA (ethylene-vinyl acetate) resin, EPDM (ethylene - propylene diene methylene linkage) rubber, nitrile rubber, acrylic rubber, and chloroprene rubber.

[0070]

If the elastic member 7 is a plastic foam as above, the elastic member 7 is light and sufficient elastic deformation can be ensured. Thus, a contact area between the elastic member 7 and the cables 11 can be ensured.

[0071]

In the present invention, a plastic foam with an elastic rebound force of 30 kPa or more at the time of 25 % compression deformation is defined as a hard plastic foam, and a plastic foam with an elastic rebound force of less than 30 kPa at the time of 25 % compression deformation is defined as a soft plastic foam. For the elastic member 7, hard plastic foams and soft plastic foams having the elastic rebound force between 15 kPa and 50 kPa may be used. In particular, a soft plastic foam with the elastic rebound force of 15 kPa or more and less than 30 kPa and a hard plastic foam with the elastic rebound force between 30 kPa and 50 kPa may be used. The reason for this is that, if the elastic rebound force exceeds 50 kPa, it becomes difficult to close the trough lid 5 and, at the same time, the material cost increases due to decrease in expansion ratio.

[0072]

On the other hand, if the elastic rebound force is less than 15 kPa, it is difficult to obtain sufficient rebound force, which leads to lack of resistance force when the cable is pulled out. If the elastic rebound force is between 15 kPa and 50 kPa at the time of 25 % compression deformation, it is easier to apply pressing force onto the cables and enough resistance force against pulling out of the cable can be obtained as well as the trough lid can be easily closed. Also, the material cost is not extremely high in this case. The preferable range of the elastic rebound force for both soft and hard plastic foam is between 20 kPa and 45 kPa.

[0073]

Here, if the elastic member 7 is made of polyethylene resin, for example, a crossdinked polyethylene plastic foam or a non-crossdinked polyethylene plastic foam can be used. However, it is preferable that a crossdinked polyethylene plastic foam is used as a hard plastic foam. Also, although there are a hard polyurethane plastic foam and a soft polyurethane resin as polyurethane resin, a hard polyurethane plastic foam is preferred to apply pressing force.

[0074]

Other than the above, it is preferable to use crossdinked resin for polystyrene resin, polypropylene resin, EVA resin, PVC resin, or the hke. The reason for this is that crossdinking increases elastic restoring force and toughness at the time of compression deformation. Also, a hard plastic foam of fire-resistant composition can be obtained from vinyl chloride resin, polyurethane resin, and polystyrene resin..

[0075]

Next, a method for fixing the elastic member 7 will be described. As shown in FIG. 9, the elastic member 7 is fixed to the reverse surface of the tough lid 5. Here, reinforcing ribs 23a and 23b are formed on the reverse surface of the trough lid 5. The reinforcing ribs 23a are formed in a direction approximately parallel to the longitudinal direction of the trough lid 5. Also, the reinforcing ribs 23b are formed in a direction approximately parallel to the width direction of the trough lid 5. That is, the reinforcing ribs 23a and 23b intersect with each other at right angles.

[0076]

The elastic member 7 is, for example, inserted into an approximately rectangular space between the reinforcing ribs 23a or between the reinforcing ribs 23b to be fixed. In this way, the elastic member 7 can be easily fixed to the reverse surface of the trough lid 5. For example, if a length of one side of the elastic member 7 is slightly larger than the distance between the reinforcing ribs 23a or the distance between the reinforcing ribs 23b, then inserting the elastic member 7 between the reinforcing ribs 23a or 23b can ensure that the elastic member 7 does not fall off from the trough lid 5.

[0077]

In particular, by inserting the elastic member 7 between the reinforcing ribs 23b which are in a direction intersecting the longitudinal direction of the trough lid 5 at right angles, it is possible to prevent the elastic member 7 from being shifted in the longitudinal direction of the trough lid 5. Thus, it is possible to prevent the elastic member 7 from being shifted along with the cable 11 in the longitudinal direction of the trough lid 5 when the cable 11 is pulled out.

[0078]

Also, by inserting the elastic member 7 into a space between the reinforcing ribs 23a or between the reinforcing ribs 23b, the elastic member 7 can be attached closely to the reverse surface of the trough lid 5. Thus, when the trough lid 5 is fixed to the trough body 3 to press the elastic member 7, compression force can be uniformly applied to the elastic member 7.

[0079]

Alternatively, the elastic member 7 may be adhered to the reverse surface of the trough lid 5 using an adhesive agent. In this way, the elastic member 7 can be fixed more securely to the reverse surface of the trough lid 5 and this can prevent shifting of the elastic member 7 against the trough lid 5. In this case, it is unnecessary to insert the elastic member 7 between the reinforcing ribs 23a or 23b.

[0080]

Also, as shown in FIG. 10, there is a case in which a reinforcing rib 23c that is parallel to the reinforcing ribs 23a is formed between the reinforcing ribs 23a. That is, there may be a case in which the space surrounded by the reinforcing ribs 23a and 23b is divided by the reinforcing rib 23c. In such a case, the elastic member 7 may be disposed being in contact with the tip ends of the reinforcing ribs 23b and 23c.

[0081]

Also, the elastic members 7 of having a size that fits into the space surrounded by the reinforcing ribs 23a, 23b, and 23c may be used and these may be inserted into the spaces surrounded by the reinforcing ribs 23a, 23b, and 23c to be fixed.

[0082]

Also, as shown in FIG. 11, there is a case in which reinforcing ribs 23d in a honeycomb dike shape is formed. In such a case, the elastic member 7 may be disposed being in contact with the tip ends of the reinforcing ribs 23d. Alternatively, the elastic member 7 having a shape that fits into the space surrounded by the reinforcing ribs 23d may be used and these may be inserted into the spaces surrounded by the reinforcing ribs 23d.

[0083]

Next, trough line using the cable theft prevention structure 1 will be described. FIG. 12 illustrates trough line 30. The trough line 30 is formed of a plurality of the trough bodies 3 and the trough lids 5 joined in the longitudinal direction thereof and includes the cables 11 laid inside the trough bodies 3.

[0084]

The trough line 30 includes the cable theft prevention structures 1 which are provided at predetermined intervals. That is, the elastic member 7 is disposed between the trough lid 5 and the cable 11 and the elastic member 7 presses the cable 11 at every predetermined interval of the trough line 30. The cable theft prevention structure 1 may be provided in every trough body 3, or may be provided in every two or more trough bodies 3. The elastic members 7 may be provided also at a plurality of locations in one trough body 3.

[0085]

As mentioned above, according to the first embodiment, the elastic member 7 presses the cable 11 and thus the resistance against pulling out of the cable 11 can be increased. As a result, the theft of cable 11 can be prevented.

[0086]

Also, a plastic foam is used as the elastic member 7 so the elastic member 7 is light and excels in handling. Also, since plastic foams have large elastic deformation capacity, the elastic member 7 can be easily deformed according to the outer shape of the cables 11 when the elastic member 7 is pressed to the cables 11. Thus, the elastic member 7 can be in close contact with the surface of the cables 11.

[0087]

Also, if the three sides of the elastic member 7 intersecting each other at right angles are different in length, the same elastic member 7 can still be used for various types of accommodation of the plurality of the cables 11. That is, by changing the direction in which the elastic member 7 is disposed, the amount of pressing force against the cable 11 can be changed.

[0088]

Also, the bundling member 12 bundles a plurality of the cables 11 so as to prevent position shifting of the cables 11. As a result, stable pressing force by the elastic member 7 can be obtained. Also, the bundling member 12 can improve the resistance against pulling force exerted onto the cable 11.

[0089]

Also, inserting the elastic member 7 between the reinforcing ribs to be fixed facilitates fixing of the elastic member 7 and enables the elastic member 7 to attach closely to the reverse surface of the trough lid 5. Thus, uniform pressing force can be applied to the elastic member 7.

[0090 ]

Also, disposing the elastic member 7 between the reinforcing ribs 23b and 23d, which are not parallel to the longitudinal direction of the trough lid 5, prevents the elastic member 7 from shifting in the longitudinal direction of the trough lid 5. Similar effect as this can also be obtained by adhering the elastic member 7 to the reverse surface of the trough lid 5.

[0091] (Second Embodiment)

Next, a second embodiment will be described. FIG. 13 (a) illustrates an elastic member 7a. In the embodiments hereinafter, the same notations as in FIG. 1 to FIG. 12 will be used for the structures having the same functions as the first embodiment and redundant descriptions will be omitted.

[0092]

The elastic member 7a has a structure approximately similar to the elastic member 7 except that the elastic member 7a is a laminated structure of a plurality of elastic bodies 25 (plastic foam). The number of laminated layers of the elastic bodies 25 is not limited to the illustrated example and may be two, or four or more. Also, a thickness of each layer may be the same for all the layers or may differ.

[0093]

As mentioned above, the elastic member 7a is preferably formed of a hard plastic foam. In this case, each of the elastic bodies 25 is a hard plastic foam. If a hard plastic foam is used for the elastic member 7a, the elastic member 7a can generate sufficient elastic rebound force and press the cable 11 firmly when being pressed by the trough lid 5.

[0094]

The elastic bodies 25 are bonded with an adhesive agent or a tacky agent (including double sided tape). Here, if the elastic body 25 is a solid bulk material, it is preferable to polish a surface thereof with paper to have a rough surface. If the elastic body 25 is a plastic foam, the surface layer has roughness and thus there is no need to polish the surface. However, it is preferable to clean the surface before bonding.

[0095]

Also, if the elastic body 25 is made of resin, widely applicable adhesive such as epoxy adhesive or urethane adhesive are generally used as a bonding agent in many cases. When using such reactive adhesives, it is necessary to clean the surface.

[0096]

Also, for olefin resin with mahadhesive property such as polyethylene resin or polypropylene resin, rubber bonding agent, epoxy agent or urethane agent can be used. Furthermore, for resin with mahadhesive property, hot-melt type adhesive, in which a polar group is introduced into a high polymer having an approximately similar frame as polyolefin so as to be compatible to both polyethylene and the polar material, can also be used. Commercially available mahadhesive resin adhesive agents for polyolefin can also be used.

[0097]

For bonding PVC resin, rubber adhesive, urethane adhesive, epoxy adhesive vinyl-chloride resin adhesive, or cyanoacrylate adhesive can be used. Also, for bonding EVA resin, EVA emulsion adhesive can be used. Also, styrene hot-melt elastomer can be used for bonding polystyrene, preferably with a surface roughening process.

[0098]

Also, if the elastic body 25 is made of thermosetting urethane resin, solvent type rubber adhesive, epoxy adhesive, or urethane adhesive can be used. Also for bonding rubber elastic bodies 25 such as EPDM rubber, nitrile rubber, acrylic rubber, or chloroprene rubber, solvent type or emulsion type adhesive of the same kind of materials can be used, and synthetic rubber solvent-type adhesive or synthetic rubber emulsion adhesive can also be used.

[0099]

Other than the above, double sided adhesive tape can be used for bonding, for example. As an adhesive material for adhesive tape, acrylic or synthetic rubber tacky agent can be used. There are various types of acrylic tacky agents, such as non-solvent type, solvent type, and emulsion type. In a view of product cost, the emulsion type is cheap so the emulsion type may be used.

[0100]

Here, other than an acrylic main monomer, other comonomers or other monomers including functional group may be mixed into the acrylic adhesive to give cohesion and tackiness. Also, to give cohesion, an isocyanate group or the like may be added. Other than the above, if the elastic body 25 is made of polyolefin resin, for an amorphous oligomer with the molecular weight between several hundreds and several thousands, adding the above monomer or the like to the base polymer in a range of several to 20 % can contribute to improvement of flowability and adhesiveness.

[0101]

Also, as a tacky adhesive agent having thermoplastic elastomer as a base polymer, there is a hot melt type. As an elastomer for a hot melt type tacky adhesive agent, other than styrene thermoplastic elastomer, EVA hot melt, ethylene-propylene copolymer or polyolefin hot melt adhesive using ethylene acrylic acid copolymer or the like can be used. Acrylic thermoplastic elastomer or polyurethane thermoplastic elastomer can also be used.

[0102]

The number of laminated layers of the elastic member 7a can be changed at sites so the thickness of the elastic member 7a can be adjusted easily by laminating and bonding the elastic bodies 25 at the site according to laying conditions of the cables and the like.

[0103]

Also, as shown in FIG. 13 (b), in the elastic member 7a, at least any one or more layers of bonding interfaces of the elastic bodies 25 may be separable (illustrated as an arrow El). If the laminated structure is separable at the laminate interface in this way, it is advantageous for height adjustment of the elastic member 7a.

[0104]

FIG. 14 (a) illustrates an example of a cable theft prevention structure lb in which one row of the cables 11 is disposed (i.e. a case in which the overall height of a group of the cables 11 is low). As mentioned above, when the overall height of the group of the cables 11 is low, it is necessary to increase the thickness of the elastic member 7a. In such a case, the elastic body 25 is used as it is. In this way, the elastic member 7a can be pressed to the cables 11 with certainty.

[0105]

On the other hand, FIG. 14 (b) illustrates an example of the cable theft prevention structure lb in which a plurality of rows of the cables 11 are disposed (i.e the overall height of the group of the cables 11 is high). If the overall height of the group of the cables 11 is high like this, it is necessary to decrease the thickness of the elastic member 7a. This is because, if the thickness of the elastic member 7a is large, it is necessary to increase the compression rate of the elastic member 7a, which makes it difficult to close the trough lid 5.

[0106]

However, if the elastic member 7a made of three layers of the elastic bodies 25 is prepared and the elastic bodies 25 that are once bonded are not delaminatable, then it is required to prepare another elastic member 7a of two layers of the elastic bodies 25. If the elastic bodies 25 can be delaminated from each other in this case, it is possible to remove one layer (or a plurality of layers) of the elastic bodies 25 to be used. This enables to press the elastic member 7a to the cables 11 with certainty and the trough lid 5 to be closed easily, independent of the height of the group of the cables 11.

[0107]

Here, to make the elastic member 7a a separable structure, it is preferable that the elastic bodies 25 are bonded with double sided tape with tackiness. Also, for example, if four layers of the elastic body 25 having a thickness of 5 mm each are laminated to make the elastic member 7a having a thickness of 20 mm, removing the fourth elastic body 25 can make the elastic member 7a having a thickness of 15 mm to be used. Also, in addition, by attaching one sheet or a combination of two sheets of a hard plastic foam sheet of 2.5 mm thickness (the elastic body 25) and/or a hard plastic foam sheet of 1.0 mm thickness (the elastic body 25), the thickness of the elastic member 7a can be adjusted to a sheet thickness of 16 mm, 17.5 mm, or 18.5 mm, for example.

[0108]

Alternatively, without separating the elastic body 25, the elastic member 7a of a thickness of 21 mm, 22.5 mm, or 23.5 mm can be obtained by further attaching a hard plastic sheet foam (the elastic body 25). Making fine adjustment of the amount of compression of the elastic member 7a in this way enables to finely adjust the pressing force applied onto the cables 11 by the elastic member 7a.

[0109]

According to the second embodiment, the same effects as in the first embodiment can be obtained. Also, since the elastic member 7a is a laminated structure of the elastic bodies 25, the thickness of the elastic member 7a can be freely changed according to the situation.

[0110] (Third Embodiment)

Next, a third embodiment will be described. FIG. 15 illustrates an elastic member 7b. The elastic member 7b has approximately the same structure as the elastic member 7a except that an elastic body (a hard plastic foam) 25a, an elastic body (a hard plastic foam) 25b, and an elastic body (a soft plastic foam) 25c are laminated.

[0111]

Each of the elastic body (a hard plastic foam) 25a, the elastic body (a hard plastic foam) 25b, and the elastic body (a soft plastic foam) 25c has different hardness (elastic repulsion force). For example, the elastic body (a hard plastic foam) 25a is a hard plastic foam, and the elastic body (a soft plastic foam) 25c is a soft plastic foam. Also, the elastic body (a hard plastic foam) 25b is a plastic foam (a hard plastic foam, for example) having the hardness (elastic repulsion force) between that of the elastic body (a hard plastic foam) 25a and that of the elastic body (a soft plastic foam) 25c. The number of laminated layers of the elastic member 7b is not limited to the illustrated example and at least one layer of a hard plastic foam and one layer of a soft plastic foam are included. That is, a soft plastic foam should be laminated on at least one of the surface layers of a hard plastic foam.

[0112]

As mentioned above, a plastic foam with an elastic rebound force between 30 kPa and 50 kPa at the time of 25 % compression can be used as a hard plastic foam, and a plastic foam with an elastic rebound force of 15 kPa or more and less than 30 kPa at the time of 25 % compression can be used as a soft plastic foam. Also, when considering that individual applicable strength ranges of elastic rebound force for the hard plastic foam and the soft plastic foam are added together, the range of 15 to 50 kPa is applicable. Thus, needless to say, the elastic rebound force of a laminated body, which is a lamination of the hard plastic foam and the soft plastic foam, is within the range of 15 to 50 kPa. Although specific descriptions are omitted, using a lamination combining plastic foams with different elastic rebound force as above makes it possible to adjust the elastic rebound force to be within more preferable range of 20 kPa and 45 kPa by, for example, appropriately selecting the hard plastic foam and the soft plastic foam having predetermined elastic rebound force within the above-mentioned range.

[0113]

FIG. 16 illustrates a cable theft prevention structure lc. The elastic member 7b includes the elastic body (a hard plastic foam) 25a being in contact with the trough body 5 and the elastic body (a soft plastic foam) 25c being in contact with the cables 11. That is, a hard plastic foam having relatively large elastic rebound force is in contact with the trough lid 5 and a soft foam having relatively small elastic rebound force is in contact with the cables 11.

[0114]

As mentioned above, from a perspective of pressing force against the cables 11, it is preferable to form the entire elastic member from the hard plastic foam. However, as shown in the cable theft prevention structure lc, it is easier to use the soft foam having relatively small elastic rebound force for the contacting surface with the cables 11 to increase the contacting area between the elastic member 7b than to use the elastic member 7b formed only from the hard plastic foam. Thus, a pressure-receiving area of the cables 11 can be increased and stress of the overall pressure-receiving surface can be increased.

[0115]

Increase in the pressure-receiving surface area can also improve friction between the elastic member 7b and the cable 11, which is applied when someone attempts to pull out and steal the cable 11. Here, it is preferable that the thickness of the laminated layer of the soft plastic foam with small elastic rebound force should not be thicker than necessary and limited to the minimum thickness so as to minimize the fall in pressing force.

[0116]

Also, making the reverse surface of the trough lid 5 into contact with the elastic body (a hard plastic foam) 25a can transmit pressing force from the trough lid 5 to the cables 11 with more certainty.

[0117]

Also in the elastic member 7b, similarly to the elastic member 7a, each layer can be removed or added. As above, even if the heights of the laminated layers are the same, it is possible to obtain different elastic rebound force by combining the elastic body (a hard plastic foam) 25a, the elastic body (a hard plastic foam) 25b, and the elastic body (a soft plastic foam) 25c having different elastic rebound force.

[0118]

According to the third embodiment, the same effects as in the second embodiment can be obtained. Also, by laminating a soft plastic foam with relatively small elastic rebound force onto the surface of a hard foamed resin, the contacting area between the elastic member 7b and the cables 11 can be increased. Also, if a plurality of types of cables 11 with different outer diameters, for example, are disposed in parallel, pressing the soft plastic foam against the cables 11 can apply the pressing force to all the cables 11.

[0119]

In any of the first, second, and third embodiments of the present invention, it is preferable to use a plastic foam as an elastic member. If a plastic foam is used as an elastic member instead of a resin sheet or a rubber member, it is easier to fix the trough lid and adjust the pressing force when the trough lid presses the plastic foam and the trough lid is fixed.

WORKING EXAMPLES [0120]

The cable theft prevention structures according to the present invention are evaluated. FIG. 17 is a perspective view showing a method for the evaluation and FIG. 18 is a cross sectional view taken along J-J line in FIG. 17.

[0121]

First, the 200 mm wide trough body 3 and the trough lid 5 are cut into a length of 200 mm. A total of fourteen cables 11 (Product No. UP9030-HS: outer diameter = 31.3 Φ · unit weight 1.5 kg/m), which are cut into 300 mm length, are disposed in three rows inside the trough body 3, as shown in the drawing. The elastic member 7 is disposed between the trough lid 5 and the cables 11. The cables 11 are not bundled.

[0122]

For the test, various plastic foams (example 1 - a hard plastic foam, example 2 - a hard plastic foam, example 3 - a soft plastic foam, and comparison 1 - a soft plastic foam), in which elastic rebound force is adjusted by changing the density (expansion ratio) and the foaming structure of the plastic foam, are used. The elastic rebound force of the soft plastic foam of the comparison 1 is extremely low as 10 kPa at the time of 25 % compression deformation in spite of the density thereof is high as 50 kg/m³. This is because, while other materials have a structure which is a mixture of closed cell structures and open cell structures and higher elastic rebound force can be obtained from those containing more percentage of closed cell structures, the soft resin foam of the comparison 1 is a plastic foam with open cell structures..

[0123] (Working Example l)

Across-linked hard polyethylene foamed body with elastic rebound force of 45 kPa and density of 40 kg/m³ at the time of 25 % compression is used as the elastic member 7. The elastic member 7 is disposed over the cables 11 and the trough lid 5 is closed so that the elastic member 7 is compressed 15 % (to a thickness of 80 mm) to press the cables 11. The trough lid 5 is fixed by a trough lid fixing member, which is not shown. In this state, pulling force required to pull out the cable 11 at the center in the top row (K in FIG. 18) is measured by a load measuring apparatus 31.

[0124] (Working Example 2)

Acrossdinked hard polyethylene foamed body with elastic rebound force of 35 kPa and density of 30 kg/m³ at the time of 25 % compression is used as the elastic member 7. The elastic member 7 is disposed above the cables 11 and the trough lid 5 is closed so that the elastic member 7 is compressed 15 % (to a thickness of 80 mm) to press the cables 11. The trough lid 5 is fixed by a trough lid fixing member, which is not shown. In this state, pulling force required to pull out the cable 11 at the center in the top row (K in FIG. 18) is measured by the load measuring apparatus 31.

[0125] (Working Example 3)

Acrossdinked soft polyethylene plastic foam with elastic rebound force of 20 kPa and density of 22.5 kg/m³ at the time of 25 % compression is used as the elastic member 7. The elastic member 7 is disposed above the cables 11 and the trough lid 5 is closed so that the elastic member 7 is compressed 15 % (to a thickness of 80 mm) to press the cables 11. The trough lid 5 is fixed by a trough lid fixing member, which is not shown. In this state, pulling force required to pull out the cable 11 at the center in the top row (K in FIG. 18) is measured by the load measuring apparatus 31.

[0126] (Comparison l)

An especially soft crossdinked polyethylene foamed body with elastic rebound force of 10 kPa and density of 50 kg/m³ at the time of 25 % compression is used as the elastic member 7. The elastic member 7 is disposed above the cables 11 and the trough lid 5 is closed so that the elastic member 7 is compressed 15 % (to a thickness of 80 mm) to press the cables 11. The trough lid 5 is fixed by a trough lid fixing member, which is not shown. In this state, pulling force required to pull out the cable 11 at the center in the top row (K in FIG. 18) is measured by the load measuring apparatus 31.

[0127] (Comparison 2)

Pulling force required to pull out the cable 11 at the center in the top row (K in

FIG. 18) without using the elastic member 7 is measured by the load measuring apparatus 31. Each result is shown in Table 1.

[0128] [Table l]

	Elastic member	Pulling out force at the time of 15% compression (kg)
Material	Density (kg/m3)	Elastic rebound force at the time of 25% compression (kPa)
Example 1		40	45	6.0
Example 2	Cross-linked polyethylene foamed body	30	35	5.0
Example 3	22.5	20	4.6
Comparison 1		50	10	1.8
Comparison 2	—	—	—	0.5

[0129]

From the results, the pulling out force in Comparison 2 in which the elastic member 7 is not used was 0.5 kg. On the other hand, in the Example 1 in which the elastic member 7 of a hard plastic foam having large elastic rebound force of 45 kPa at the time of 25 % compression was used, the pulling force was 6.0 kg, which is twelve times that in Comparison 2, and in the next Example 2 in which the elastic rebound force was 35 kPa, the pulling out force was 5.0 kg, which is ten times that in Comparison 2, enabling to increase the pulling out force for the cable 11 substantially. Also, when the elastic member with elastic rebound force of 20 kPa at the time of 25 % compression in Example 3 was used, the pulling out force was still 4.6 kg and there was no substantial fall in the pulling out force.

[0130]

On the other hand, in Comparison 1 in which the plastic foam with extremely low elastic rebound force of 10 kPa at the time of 25 % compression was used, the pulling out force was low as 1.8 kg and the effect of the elastic member 7 for improving the pulling out force was insufficient. The reason for this was that the material used for Comparison 1 was a plastic foam with open cell structures.

[0131]

Next, the pulling out force when the present cable theft prevention structure 1 is used in the trough line 30 will be examined. FIG. 19 shows a state in which the cable theft prevention structures 1 (the elastic members 7) are disposed at a predetermined pitch (M in the drawing) in the trough line (overall length L).

[0132]

For example, with the overall length L = 50 m and the elastic member pitch M - 4 m, the pulling out force for the cable when the elastic member 7 used in Example 1 is applied will be estimated. First, the pulling out force due to friction of the cable itself and the like without the elastic member 7 is 0.5 kg I 0.3 m = approximately 1.67 kg/m from Table 1, and thus 50 m * 1.67 kg/m = 83.5 kg.

[0133]

From Table 1, the pulling out force for the cable when the elastic member 7 used in Example 1 is applied will be estimated. From Table 1, the pulling force increased by the elastic member 7 is 6.0 kg - 0.5 kg = 5.5 kg. The elastic members 7 are disposed at twelve locations in 50 m if disposed at a pitch of 4 m. Thus, the pulling out force due to the elastic members 7 is 5.5 kg * 12 locations = 66 kg. Thus, the total pulling out force is 149.5 kg, which is increased by approximately 80 % compared to the case in which no elastic members 7 are used.

[0134]

Also, the pulling out force increased by the elastic member 7 used in Example 2 is 5.0 kg 0.5 kg = 4.5 kg. The elastic members 7 are disposed at twelve locations in 50 m if disposed at a pitch of 4 m. Thus, the pulling out force due to the elastic members 7 is 4.5 kg * 12 locations = 54 kg. Thus, the total pulling out force is 137.5 kg, which is increased by approximately 65 % compared to the case in which no elastic members 7 are used.

[0135]

Similarly, the pulling out force increased by the elastic member 7 used in Example 3 is 4.6 kg - 0.5 kg = 4.1 kg. The elastic members 7 are disposed at twelve locations in 50 m if disposed at a pitch of 4 m. Thus, the pulling out force due to the elastic members 7 is 4.1 kg * 12 locations = 49.2 kg. Thus, the total pulling out force is 132.7 kg, which is increased by approximately 59 % compared to the case in which no elastic members 7 are used. The pulling out force did not fall drastically here in the case in which the soft plastic foam in Example 3 was used. The reason for this is the increase in the contacting area between the cables and the resin.

[0136]

On the other hand, the pulling out force increased by the elastic member 7 used in Comparison 1 is 1.8 kg - 0.5 kg = 1.3 kg. The elastic members 7 are disposed at twelve locations in 50 m if disposed at a pitch of 4 m. Thus, the pulling out force due to the elastic members 7 is 1.3 kg * 12 locations = 15.6 kg. Thus, the total pulling out force is 99.1 kg, which is increased only by approximately 19 % compared to the case in which no elastic members 7 are used. Here, it can be considered that, when the material in Comparison 1 is used as the elastic member, the fall in elastic rebound force cannot be compensated by the increase in the contact area between the cables and the plastic foam, causing friction resistance at the time of being pulled out to fall.

[0137]

Here, to further increase the pulling out force, elastic rebound force or compression amount of the elastic member may be increased, or disposing locations of the elastic member 7 in the trough line 30 may be increased by reducing the disposing pitch of the elastic members 7. Alternatively, the further longer elastic member 7 may be used at each cable theft prevention structure. Also, bundling the cables 11 together may possibly increase friction between the cables.

[0138]

Although the embodiments of the present invention have been described referring to the attached drawings, the technical scope of the present invention is not limited to the embodiments described above. It is obvious that persons skilled in the art can think out various examples of changes or modifications within the scope of the technical idea disclosed in the claims, and it will be understood that they naturally belong to the technical scope of the present invention.

DESCRIPTION OF NOTATIONS [0139]

1, lb, lc, Id, le..........cable theft prevention structure

3..........trough body

5..........trough lid

7, 7a, 7b..........elastic member

9, 9a, 9b..........trough lid fixing member

..........cable

..........bundling member a, 13b..........fitting portion

15..........fixing portion

17..........hole

19..........groove

21..........locking portion

23a, 23b, 23c, 23d..........reinforcing rib

25..........elastic body

25a, 25b..........elastic body (hard plastic foam)

25c..........elastic body (soft plastic foam)

27, 27a..........gripping member

..........buckle

..........trough line

..........load measuring apparatus

Claims (18)

WHAT IS CLAIMED IS

1. A cable theft prevention method, wherein:

an elastic member is disposed between a cable and a trough lid, the cable being laid inside a trough body and the trough lid covering an upper part of the trough body!

a reverse surface of the trough lid is in contact with the elastic member! and the reverse surface of the trough lid further presses the elastic member so that the elastic member presses the cable.

2. The cable theft prevention method according to claim 1, wherein:

the elastic member is a plastic foam.

3. The cable theft prevention method according to claim 2, wherein:

the plastic foam has two end faces!

one of the end faces of the plastic foam is in contact with the reverse surface of the trough lid! and the other end face of the plastic foam presses the cable.

4. The cable theft prevention method according to claim 2, wherein:

a plurality of reinforcing ribs are formed on the reverse surface of the trough lid! and the plastic foam is inserted between the reinforcing ribs on the reverse surface of the trough lid to be fixed and pressed, or the plastic foam is in contact with tip ends of the reinforcing ribs to be pressed.

5. The cable theft prevention method according to claim 4, wherein:

the reinforcing ribs are parallel to a longitudinal direction of the trough lid and/or parallel to a width direction of the trough lid.

6. The cable theft prevention method according to claim 2, wherein:

the plastic foam is in an approximately rectangular parallelepiped shape and three sides of the elastic member intersecting with each other at right angles vary in length.

7. The cable theft prevention method according to claim 2, wherein:

a plurality of the cables are disposed inside the trough body and the plurality of the cables are bundled together with a bundling member.

8. The cable theft prevention method according to claim 2, wherein:

the plastic foam is a laminated structure formed of a plurality of layers of plastic foams.

9. The cable theft prevention method according to claim 8, wherein:

the laminated structure includes at least one of a hard plastic foam and a soft plastic foam.

10. The cable theft prevention method according to claim 9, wherein:

the laminated structure includes the soft plastic foam laminated on an surface layer of the hard plastic foam;

the soft plastic foam is in contact with the cable! and the hard plastic foam is in contact with the trough lid side.

11. The cable theft prevention method according to claim 8, wherein:

layers in the laminated structure are bonded to each other using an adhesive agent or a tacky agent.

12. The cable theft prevention method according to claim 2, wherein:

the plastic foam has elastic rebound force between 15 kPa and 50 kPa at the time of 25 % compression deformation.

13. The cable theft prevention method according to claim 1, wherein:

the elastic member is adhered to the trough lid.

14. The cable theft prevention method according to claim 1, wherein:

the elastic member is formed of any one of plastic foams or rubber foam bodies selected from a group consisting of polyethylene resin, polypropylene resin, polystyrene resin, polyurethane resin, PVC resin, EVA resin, EPDM rubber, nitrile rubber, acrylic rubber, and chloroprene rubber.

15. The cable theft prevention method according to claim 1, wherein:

the trough lid is fixed to the trough body by using a trough lid fixing member and the trough lid fixing member presses the trough lid so that the elastic member is pressed to the cable.

16. A cable theft prevention structure comprising:

a trough body!

a trough lid that covers an upper part of the trough body and is fixed to the trough body!

a cable that is laid inside the trough body! a cable pressing member that presses the cable! and a pressing force applying member that applies pressing force to the cable pressing member, wherein the cable pressing member is disposed between the cable and the trough lid; the cable pressing member is an elastic member that is in contact with a reverse surface of the trough lid and the cable!

the pressing force applying member presses the trough lid so that the cable pressing member is pressed to the cable through the trough lid.

17. The cable theft prevention structure according to claim 16, wherein:

the pressing force applying member is a trough lid fixing member that fixes the trough lid to the trough body!

the trough lid fixing member is either a fixing bolt, a fixing buckle, or a fixing band.

18. Trough line comprising:

a plurality of the trough bodies and the trough lids that are joined together, wherein a plurality of the cable theft prevention structures according to claim 16 are provided at a plurality of locations.