JP7215676B2 - lightweight lid for pits - Google Patents

Description

The present invention relates to lightweight lids for pits located along the path of travel.

A path of travel, such as a railroad, is provided with pits (sometimes called "ducts") along it. Generally, the pit consists of a U-shaped concrete ditch that houses communication lines and other components necessary for railway operation. The pit is covered with a lid to form a so-called berm.
In this way, pit covers were required to be strong enough to support human walking as berms, so they were made of concrete or metal like pits.
Please refer to Patent Document 1 as a prior document disclosing the technology related to the present invention.

Utility Model Registration No. 3162518

If the pit lid is made of concrete or metal, sufficient strength can be ensured, but on the other hand, the weight is a problem from the viewpoint of the function required for the lid, that is, the ease of installation/removal. Become.
In view of the number of man-hours for installation, it is preferable to lengthen the lid in the axial direction of the pit, but if it is too long, the weight of the lid will interfere with the attachment and detachment work.
On the other hand, if the lid is shortened, the attachment and detachment work becomes easier, but the number of man-hours required for installation is increased, and the lid itself becomes too light, which causes the problem of displacement and detachment.
Generally, the mass of such a lid is set to 30 to 60 kg, and the length is appropriately determined according to the width of the pit and the usage environment.

However, since most of the attaching and detaching work of the lid is done by hand, the lid weighing 30 to 60 kg has been a heavy burden on workers. Therefore, there is a strong demand to reduce the weight of the pit lid (for example, 10 kg or less). However, if the lid is lightened, it becomes difficult to maintain the strength to support human walking, and the sense of stability (preventing slippage and detachment from the pit) is likely to be lost.

The present inventors have made intensive studies to solve the above problems, and as a result, have arrived at the following invention. That is, the first aspect of the present invention is defined as follows.
A lightweight pit lid positioned along the path of travel, comprising:
a rectangular plate-like main body;
a reinforcing portion provided in the main body;
one of a pair of opposing edges of the main body is provided with an upward taper, and the other is provided with a downward taper;
In the laying state of the lid, the upward taper is positioned on the starting end side and the downward taper is positioned on the terminal end side with reference to the moving direction of the moving body on the moving path.
Lightweight lid for pits.

According to the lightweight lid for the pit (hereinafter sometimes simply referred to as a lid) of the first aspect defined in this way, since the main body is provided with the reinforcing portion, the strength to support human walking is ensured. .
In addition, of the pair of opposite edges of the main body, the edges on the starting end side in the moving direction of the moving body are provided with an upward taper, and the edges on the other end side are provided with a downward taper. When the lids are installed in the pit without gaps, the upward tapers and the downward tapers of the adjacent lids overlap each other. At this time, the downward taper formed on the terminating edge of the main body of the lid overlaps the upward taper formed on the leading edge of the adjacent lid main body. Wind pressure is applied to the lid as the moving body moves on the movement path. This wind pressure is in the direction from the beginning to the end of the travel path, so that the downward taper on the terminal end of the lid suppresses the upward taper on the adjacent lid. Therefore, even if the lid itself is light, stability is ensured and the lid does not shift or come off.

A second aspect of the invention is defined as follows. Namely
A lightweight lid for a pit as defined in the first aspect, wherein the body portion is provided with an air vent window only at a portion of the downwardly tapered rim.
According to the lightweight cover for the pit of the second aspect defined in this way, since the air vent window is provided on the edge provided with the downward taper, when the upper surface of the cover becomes negative pressure (i.e., when the moving body passes through Afterwards, etc.), the air in the pit escapes through the air vent window, so the negative pressure itself is reduced. becomes smaller. Therefore, the pressing force of the downward taper against the upward taper of the adjacent lid is maintained. Adjacent lids are often under negative pressure, so maintaining a downward taper pressure with an air release window stabilizes the laying of the adjacent lids.
If the air vent window is formed only on the downward taper side, it becomes a mark indicating the position of the edge where the downward taper is formed. Therefore, the arrangement direction of the lid can be grasped at a glance, thereby facilitating the operation of laying the lid.

A third aspect of the present invention is defined as follows. Namely
In the lightweight lid for the pit specified in the first aspect, the main body portion is provided with an air vent slit at the edge of the downward taper, and the air vent slit hits the upper edge of the pit on the back surface of the main body portion. Starting from the abutment area, the abutment area is formed toward the central side and wider than the downward taper.
According to the lightweight lid for the pit of the third aspect thus constructed, the slit-like air vent window has a narrow width. Therefore, it becomes less likely to become an obstacle when a person walks on the lid. Furthermore, since the contact area that contacts the upper edge of the pit on the back surface of the main body is formed toward the central side as a starting point, the air vent slit is in contact with the upper edge of the pit when it is laid in the pit. . In other words, the slit is formed at the endmost end on the upper surface of the main body. Therefore, it is possible to prevent obstruction of human walking.
The reason why the downward taper is wider than the downward taper is that the downward taper overlaps with the upward taper of the adjacent lid, so making the downward taper wider than the downward taper ensures better air venting.

A fourth aspect of the present invention is defined as follows. That is, in the lightweight cover for the pit specified in the third aspect, the width of the air vent slit is twice the width of the downward taper, and the length thereof is the same length as the width of the contact area. be.
According to the lightweight lid for the pit of the fourth aspect defined in this way, the air vent slit exposed on the main body has a predetermined width (the same width as the downward taper) and a predetermined length (the upper surface of the slit the same length as the width). By defining the shape of the air vent slit in this way, the design of the lid is improved. In addition, since the shape of the air vent slit is standardized, it becomes easy to design lids for pits of different sizes and shapes.
In the above description, "twice the width of the downward taper" and "same length as the width of the contact area" are not "twice" or "same length" in a strict physical sense. Needless to say, it has a certain margin allowed as an industrial product.

A fifth aspect of the present invention is defined as follows. Namely
In the lightweight lid for the pit defined in any one of the first to fourth aspects, the reinforcing portion includes ribs extending in the width direction of the pit formed on the back surface of the main body portion.
According to the lightweight lid for the pit defined in the fifth aspect defined in this way, the ribs are arranged in the width direction of the pit. Therefore, the strength in the width direction is improved, and even if a person gets on the central portion of the lid, the lid is hardly deformed.
Such ribs can be arranged along the edge having an upward taper and the edge having a downward taper of the main body (sixth aspect).

A seventh aspect of the present invention is defined as follows. That is, in the lightweight lid for the pit specified in the third or fourth aspect, a rib is provided on the back surface of the main body as the reinforcing portion, and the rib is in contact with the upper edge of the pit at the portion diagonal to the air vent slit. The distance between the abutting area and the edge of the rib is smaller than the height of the rib.
The lightweight lid for the pit of the seventh aspect thus defined prevents it from being flipped out of the pit.
Negative pressure may be applied to the upper surface of the lid due to the effects of moving objects and natural wind. At that time, the negative pressure is relatively reduced in the portion where the air vent slit is present compared to other portions due to the movement of the air through the slit. Therefore, the negative pressure becomes an upward force (rotational force) that tries to turn up the lid, with the part where the air vent slit is provided as a fulcrum. The component of this upward force in the axial direction of the pit is suppressed by the interaction between the upward tapered surface and the downward tapered surface. On the other hand, the upward movement of the pit width direction component of the upward force is restricted by the interference of the rib end (bottom edge) diagonal to the air vent slit with the inner peripheral surface of the pit. be. This can prevent the lid from coming off the pit even if the lid is made lightweight.

An upward force may act on the lid due to vibration or other unintended external force. This upward external force rarely acts perpendicularly to the lid, and becomes an upward rotational force with the portion supported by the pit as a fulcrum. That is, the part other than the part with the air vent slit may serve as the fulcrum. Therefore, the ends of all the ribs are placed as close to the inner peripheral wall of the pit as possible within a range that does not interfere with the attachment/detachment work. Make it interfere with the inner peripheral wall. That is, the distance between the contact area contacting the upper edge of the pit on the back surface of the main body and one end of the rib is made smaller than the height of the rib (eighth aspect).

A ninth aspect of the present invention is defined as follows: the lid defined in any one of the fifth to eighth aspects, wherein the main body is made of wood, and the back surface of the main body has the A reinforcing layer is attached between the ribs and the entire surface is covered with a layer of protective material. By making the main body part of wood in this way, the weight of the lid can be significantly reduced. The weight of the lid is for example 15-25 kg/m ² , preferably 20 kg/m ² . The strength of the wooden body is provided by ribs and reinforcing layers. By covering the entire surface with a protective material layer, weather resistance is ensured and fire prevention measures are taken.
In the above, the main body is formed of the first plywood in which the fiber directions of the single plate are orthogonal, and the ribs are formed of the second plywood in which the fiber directions of the single plate are all aligned in the length direction of the ribs, and are reinforced The layer is preferably in the form of a sheet or net of aramid fiber (tenth aspect).
In order to reduce the weight of the lid while securing sufficient strength to support human walking, the combination of each element defined in the tenth aspect and its material is considered to be the best matching.
In order to suppress the movement of the lid, the inclination angle of the upward taper and the inclination angle of the downward taper should be the same (for example, 10 to 70 degrees). Then, the planes forming each taper are parallel.

As a result, the upward taper and the downward taper of the adjacent lids are overlapped without any gap. Therefore, not only is the sealing property against rainwater improved, but it does not become an obstacle to people's walking. In addition, since the layers are overlapped without gaps, stress concentration can be avoided when repeated vibrations are applied, thereby improving durability.
Furthermore, when a negative pressure is applied to the upper surface of the lid, the air inside the pit is preferentially released to the outside through the air vent slit. Therefore, the stability of the lid laid in the pit is improved.

FIG. 1 is a trihedral view showing the structure of a lightweight lid according to an embodiment of the present invention. FIG. 2 is an enlarged view of FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.
The lightweight lid 10 of the embodiment is suitably used for a pit arranged along a railroad track, and includes a main body portion 11 and a reinforcing portion 20. As shown in FIG.
The main body portion 11 is a rectangular plate material, and has an upward taper 12 and a downward taper 13 formed on opposite long edges. A slit 15 is formed in the edge having a downward taper 13, where the taper disappears. A region of a predetermined width A1 from the short edge of the back surface of the body portion 11 is placed on the upper edge of the pit 1 and serves as a contact region 17 that abuts thereon.

In the above, it is preferable that the body part 11 is made of wood from the viewpoint of weight reduction. In this example, the single plate was made of the first plywood having orthogonal fiber directions. Since a person rides on the body part 10, loads are applied from all directions. Therefore, by using the first plywood which has no isotropic load bearing strength, that is, which has the same load strength against loads from all directions, cracking and cracking can be reliably prevented.
Of course, the material of the body portion 11 is not limited to the first plywood, and a solid wood board or a plastic board can be used.
In this example, the width B1 of the main body 11 is 1000 mm, the length C1 of the pit 1 in the axial direction is 500 mm, and the thickness is 15 mm. can.

A taper is formed along the entire circumference of the long edge of the body portion 11 . An upward taper 12 is formed on the lower long edge in the figure, and a downward taper 13 is formed on the upper long edge in the figure.
When the lid 10 is laid in the pit 1, the upward taper 12 is on the beginning side of the track. In other words, the train runs from the upward taper 12 side to the downward taper 13 side.
Each taper 12, 13 is formed in a plane. The angle of inclination of each taper 12, 13 (the included angle with the perpendicular to the body portion 11) can be 10 to 70 degrees. In this example, the tilt angle is set to 15 degrees.
It is assumed that the tapers 12 and 13 have the same inclination angle. As a result, both can be superimposed on each other without a gap.
This taper can be formed all or part of the long edge. It is also possible to partially change the inclination angle.

The air vent slit 15 is in contact with the imaginary inner boundary line 18 of the contact area 17 at its starting end. As a result, the air vent slit 15 is formed on the upper surface of the body portion 11 at the edge thereof.
The air vent slit 15 extends along the downward taper 13 by the same length A1 as the width A1 of the contact area 17 . In this example, the width of A1 is set to 100 mm. The width A2 of the air vent slit 15 is twice the width A3 of the downward taper. In this example, the width A3 of the downward taper is 5 mm, and the width A3 of the air vent slit 15 is 10 mm. Also in this example, the bottom surface of the air vent slit 15 is an inclined surface parallel to the downward taper 13 . As a result, the width of the air vent slit 15 exposed on the main body 11 is 5 mm. By narrowing the width of the air vent slit in this way, it does not interfere with the walking of people.

In the above example, the air vent slit 15 is formed only on the end side of the edge on the terminal end side of the body portion 11 . Such an air vent slit 15 can serve as a mark for determining the position of the lid 10 when laying the lid.
This air vent slit 15 stabilizes the lid 10 . When a negative pressure is applied to the lid 10 after a train has passed, the air in the pit 15 is released to the outside through the air vent slit 15. - 特許庁Thus, the negative pressure can be reduced and the stability of the lid 10 can be ensured.

The air vent slit 15 communicates the inner space and the outer space of the pit 1 to reduce the negative pressure applied to the lid. From this point of view, the air vent window is not limited to a slit shape. For example, one or more independent through-holes may be formed. It does not preclude providing such an air vent window on the edge side having an upward taper.

When the main body portion 11 is made of wood, it is difficult to ensure sufficient rigidity, considering that a person walks. Of course, even if the main body part 11 is made of wood, the rigidity can be ensured by making it thicker.
Therefore, in this example, a reinforcing portion 20 is provided on the back surface of the main body portion 11 made of thin plywood. This reinforcing portion can also be provided on the surface of or inside the body portion 10 .

The reinforcing part 20 in this example comprises ribs 21 , 23 and a reinforcing layer 25 .
Ribs 21 , 23 are attached to the back surface of body portion 10 along edges having upward tapers 12 and downward tapers 13 . Ribs 21 and 23 are preferably positioned as close as possible to upward taper 12 and downward taper 13, respectively. As a result, each taper deformation is suppressed, and the bonding between the two is stabilized.
When attaching the ribs 21 (23), it is preferable to form grooves 27 (see FIG. 2) on the back surface of the main body 10 and force fit the ribs 21 (23) into the grooves 27 together with an adhesive.

In this example, ribs 21, 23 are provided parallel to the edges with respective tapers 12, 13, but the ribs can also be provided obliquely to these edges. Three or more ribs may be provided.
The ribs 21 and 23 are preferably made of the second plywood in which all the fiber directions of the single plate are aligned in the longitudinal direction of the ribs. The direction in which the fibers are arranged is parallel to the tapers 12 and 13 .
The ribs 21 and 23 are not limited to the second plywood, and synthetic resin or metal pipes can be used. Avoid using conductive or magnetic metals in facilities affected by strong magnetic fields.

It is preferable that the length B2 of the ribs 21 (the same applies to the ribs 23) is as long as possible from the standpoint of reinforcing the main body 10 more strongly. In this example, the width B1 of the main body 11 is 1000 mm, the width is 780 mm, and the height is 40 mm. That is, the rib 21 is made as long as possible within a range in which the tip of the rib 21 does not interfere with the pit 1 when the lid 10 is attached or detached and does not hinder the attaching and detaching work.
On the other hand, when a negative pressure is applied to the upper surface of the lid 10 having the air vent slit 15, a rotational force 30 is applied around the air vent slit 15 as a fulcrum (see FIG. 2). As a result, the edge 29 of the lower surface of the rib 21 interferes with the inner peripheral wall of the pit 1, preventing the lid 10 from coming off. Therefore, the distance from the tip of the rib 21 to the inner peripheral wall of the pit 1 , that is, the distance L1 from the tip of the rib 21 to the contact area 17 is set smaller than the height L2 of the pit 1 . Preferably, L1 is less than half of L2.

The reinforcing layer 25 is attached between the ribs 21 and 23 on the back surface of the body portion 11 . In this example, an aramid fiber sheet (basis weight: 100 to 900 g/m ² , more preferably 400 g/m ² ) was used as a reinforcing layer and adhered to the back surface of the main body 11 with an epoxy resin. The reinforcement layer 25 enhances the toughness of the body portion 11 . That is, when the main body 11 made of thin plywood is bent, it is prevented from being cracked or the like. The ribs 21 and 23 are in charge of preventing deformation (bending) of the body portion 11 .
It is preferable that the reinforcing layer 25 is woven in a sheet-like or net-like form using fibers having a high tensile strength. Aramid fibers, glass fibers, and the like can be used as such fibers. Among them, aramid fibers are excellent in elasticity, so that the main body portion 11 can be provided with higher toughness.
The selection of the fibers of the reinforcing layer 25, the weaving method, and the attachment area to the main body 11 can be arbitrarily selected according to the application of the lid, the usage environment, and the like. The reinforcing layer 25 may be further arranged on the upper surface of the main body portion 11 . When the body portion 11 is made of plywood, the reinforcing layer 25 may be inserted inside.

The main body portion 11 and the reinforcing portion 20 are entirely covered with a protective material layer. In this example, a polyurea resin was used as the protective material layer, and was applied to an average thickness of 1 mm or more by a spray method. As long as this protective material layer has weather resistance (water resistance, heat resistance, light resistance) and flame resistance, general flame-retardant resin such as fluororesin and polyphenol resin can be used in addition to polyurea.
It is preferable that the surface of the body portion 11 is entirely or partially subjected to a non-slip treatment. Silica sand blowing is an example of anti-slip processing.

The lid of the embodiment constructed in this manner satisfies the following specifications.
Load weight: 300 kgf/ ^m2 or more Displacement: 5 mm or less when loaded Weight: 10 kg/piece Flame resistance: UL standard V0

As previously mentioned, the lid is made entirely of non-conductive and non-magnetic material. Therefore, it can be applied to facilities such as the electromagnetic environment in infrastructure.
The lid can be applied to pits along highways, runways, etc., as well as railroad tracks.
When the installation of pits on general roads where automatic driving of cars is progressing, it is also used as a lid for the pits.

Examples of infrastructure include, for example, substations and other power facilities. The present invention can be applied as a lightweight lid for cable pits provided in such power facilities.
That is, another aspect of the present invention is defined as follows.
(1) A lightweight lid for a pit, comprising:
a rectangular plate-like main body;
a reinforcing portion provided in the main body;
A lightweight lid for a pit, wherein one of a pair of opposing edges of the body portion is provided with an upward taper and the other is provided with a downward taper.
(2) The lightweight lid according to (1), wherein the main body portion is provided with an air vent slit only in a portion of the edge provided with the downward taper.
(3) The main body portion is provided with an air vent slit at the edge of the downward taper, and the air vent slit is directed toward the central side from the contact area that contacts the upper edge of the pit on the back surface of the main body portion as a starting end, The lightweight lid according to (1), which is wider than the downward taper.
(4) The lightweight lid according to (3), wherein the width of the air vent slit is twice the width of the taper, and the length thereof is the same length as the width of the contact area.
(5)
The lightweight lid according to any one of (1) to (4), wherein the reinforcing portion includes ribs extending in the width direction of the pit formed on the back surface of the body portion.
(6)
6. The lightweight lid of claim 5, wherein said ribs are formed along each of said pair of edges.
(7)
A rib is provided on the back surface of the main body as the reinforcing portion, and the distance between the contact area that contacts the upper edge of the pit at the diagonal portion of the air vent slit and the end of the rib is greater than the height of the rib. A lightweight lid according to (3) or (4), which is small.
(8)
The lightweight cover according to any one of (4) to (6), wherein a distance between a region in contact with the upper edge of the pit on the back surface of the main body and one end of the rib is smaller than the height of the rib.
(9)
According to any one of (5) to (8), the main body is made of wood, a reinforcing layer is attached between the ribs on the back surface of the main body, and the entire surface is covered with a protective material layer. lightweight lid.
(10)
The main body is made of a first plywood in which the fiber direction of the single plate is orthogonal,
The rib is made of a second plywood in which all the fiber directions of the veneer are aligned in the length direction of the rib,
The lightweight lid according to (9), wherein the reinforcing layer is made of aramid fiber net.
(11)
The inclination angle of the upward taper and the inclination angle of the downward taper are the same,
A lightweight lid according to any one of (1) to (10).
(12)
A lightweight lid for a pit according to any one of (1) to (11), having a weight of 15-20 kg/m ² , preferably 20 kg/m ² .

1 Pit 10 Lightweight lid 11 Main body 12 Upward taper 13 Downward taper 15 Air vent slit 20 Protective parts 21, 23 Rib 25 Protective layer

Claims (13)

A lightweight lid for a pit positioned along a path of travel, comprising:
a rectangular plate-like main body;
a reinforcing portion provided in the main body;
An upward taper is provided on one of a pair of opposing edges of the main body, and a downward taper is provided on the other , wherein the inclined surface of the upward taper extends in the direction of the negative pressure applied to the main body from the moving body. an orientation, the inclined surface of the downward taper facing in a direction opposite to the direction of the negative pressure;
In the laying state of the lid, the upward taper is positioned on the starting end side and the downward taper is positioned on the terminal end side with reference to the moving direction of the moving body on the moving path.
Lightweight lid for pits. 2. The lightweight lid according to claim 1, wherein said main body portion is provided with an air vent slit only on a portion of said terminating edge . 3. The lightweight lid of claim 2, wherein the slit is formed along the edge of the terminal side. The main body portion is provided with an air vent slit at the edge of the terminal end side , and the air vent slit is centered along the edge of the terminal end side starting from the contact area that contacts the upper edge of the pit on the back surface of the main body portion. 2. The lightweight lid according to claim 1, which is formed toward the side and wider than the width in the direction of inclination of the downwardly tapered inclined surface . 5. A lightweight lid according to claim 4, wherein the width of said vent slit is twice the width of said taper and its length is as long as the width of said abutment area. The lightweight lid according to any one of claims 1 to 5, wherein said reinforcing portion includes a rib extending in the width direction of said pit formed on the back surface of said body portion. 7. The lightweight lid of claim 6, wherein said ribs are formed along each of said pair of edges. 6. A rib having the same height as the reinforcing portion is provided on the back surface of the main body, and the distance between the contact area of the back surface of the main body and the end of the rib is smaller than the height of the rib. Lightweight lid as described. The lightweight lid according to any one of claims 5 to 7 , wherein a distance between an area abutting the upper edge of the pit on the back surface of the main body and one end of the rib is smaller than the height of the rib. The lightweight body according to any one of claims 6 to 9 , wherein the main body is made of wood, a reinforcing layer is attached between the ribs on the back surface of the main body, and the entire surface is covered with a protective material layer. lid. The main body is made of a first plywood in which the fiber direction of the single plate is orthogonal,
The rib is made of a second plywood in which all the fiber directions of the veneer are aligned in the length direction of the rib,
11. The lightweight lid according to claim 10 , wherein said reinforcing layer is made of sheet-like or net-like aramid fiber. A lightweight lid according to any preceding claim , wherein the angle of inclination of the upward taper and the angle of inclination of the downward taper are the same. A lightweight lid for pits according to any of the preceding claims , having a weight of 15-20 kg/ m ² , preferably 20 kg/ m ² .

Images