JP2020111994A - Lightweight lid for pit - Google Patents

Abstract

To reduce the weight of a lid for a pit installed along a travel path such as railways, while ensuring strength and stability.SOLUTION: There is provided a lightweight lid for a pit located along a travel path, comprising a rectangular flat plate body 11 and a reinforcing portion 20 provided on the body, on which an upward taper 12 is provided on one side of a pair of opposing edges of the body, and a downward taper 13 is provided on the other side. In a state where the lid is installed, the upward taper is located at a beginning side and the downward taper is located at an end side with respect to a direction of movement of a moving object on the travel path. An air vent slit 15 is formed on the downward taper side.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lightweight lid for a pit arranged along a moving path.

A pit (sometimes called a "duct") is provided along a moving path, for example, a railway. Generally, this pit consists of a U-shaped groove made of concrete and accommodates communication lines and other members necessary for railway operation. A so-called dog running is formed by covering the pit with a lid.
As described above, since the pit lid is required to have strength to support walking of a person as a dog running, its material is made of concrete or metal like the pit.
Please refer to Patent Document 1 as a prior document disclosing a technique related to the present invention.

Utility model registration No. 3162518

If the pit lid is made of concrete or metal, sufficient strength can be secured, but on the other hand, its weight is a problem from the viewpoint of the function required for the lid, that is, the ease of mounting/removing. Become.
From the standpoint of man-hours for installation, it is preferable to lengthen the lid in the axial direction of the pit, but if the lid is made too long, the weight thereof will hinder the attachment and detachment work of the lid.
On the other hand, if the lid is made shorter, the work of attaching and detaching the lid becomes easier, but not only the man-hours for installation become bulky, but also the lid itself becomes too light and problems such as displacement and detachment occur.
Generally, the mass of the lid is set to 30 to 60 kg, and the length thereof is appropriately determined according to the width of the pit and the usage environment.

However, since the attachment/detachment work of the lid is almost manually performed, the lid having a weight of 30 to 60 kg is a heavy burden on the worker. 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 the walking of a person, and the sense of stability (preventing deviation from the pit or detachment) is easily lost.

The inventors of the present invention have come up with the following invention as a result of earnest studies to solve the above problems. That is, the first aspect of the present invention is defined as follows.
A lightweight pit lid placed along the path of travel,
A rectangular flat plate-shaped main body,
A reinforcing portion provided on the main body,
An upward taper is provided on one of a pair of opposing edges in the main body, and a downward taper is provided on the other side.
In the laid state of the lid, with the moving direction of the moving body on the moving path as a reference, the upward taper is located on the starting end side and the downward taper is located on the terminal end side.
Lightweight lid for the pit.

According to the light weight lid for the pit of the first aspect defined in this way (hereinafter, also simply referred to as a lid), since the reinforcing portion is provided in the main body portion, the strength to support walking of a person is secured. ..
Further, the pair of edges of the main body portion facing each other, which are the edges on the start 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 lid is laid in the pit without any gap, the upward taper and the downward taper of the adjacent lids overlap each other. At this time, the downward taper formed on the edge on the terminal end side of the main body portion of the lid overlaps with the upward taper formed on the edge on the start end side of the adjacent main body portion of the lid. Wind pressure is applied to the lid as the moving body moves on the moving path. This wind pressure is in the direction from the start end of the moving path to the end side, and as a result, the downward taper on the end side of the lid suppresses the upward taper of the adjacent lid. Therefore, the lid having such a structure is stable and does not slip or come off even if the lid itself is lightened.

The second aspect of the present invention is defined as follows. That is,
The lightweight lid for a pit defined in the first aspect, wherein the main body portion is provided with an air vent window only at a part of the edge provided with the downward taper.
According to the light weight lid for the pit of the second aspect defined in this way, since the air vent window is provided at the edge that is provided with the downward taper, when the upper surface of the lid becomes negative pressure (when the moving body passes through). Since the air in the pit escapes from the air vent window, the negative pressure is not only diminished, but when negative pressure is generated, the negative pressure applied to the downward taper with the air vent window is lower than that in other parts. Becomes smaller. Therefore, the pressing force of the downward taper against the upward taper of the adjacent lid is maintained. Since the negative pressure is often applied to the adjacent lids, maintaining the pressing force of the downward taper provided with the air vent window stabilizes the laid state of the adjacent lids.
If the air vent window is formed only on the downward taper side, it serves as a mark indicating the position of the edge where the downward taper is formed. Therefore, the direction in which the lid is arranged can be grasped at a glance, which facilitates the work for laying the lid.

The third aspect of the present invention is defined as follows. That is,
A lightweight lid for a pit as defined in the first aspect, wherein the main body portion is provided with an air vent slit on the downward taper edge, and the air vent slit hits the upper edge of the pit on the back surface of the main body portion. It is formed to have a width wider than the downward taper, starting from the contact area in contact with the contact end.
According to the light weight lid for the pit of the third aspect configured in this manner, the air vent window has a slit shape, so that it has a narrow width. Therefore, it becomes difficult for a person to walk on the lid. Furthermore, since the back surface of the main body is formed toward the center with the contact area that contacts the upper edge of the pit as the starting end, the air vent slit will contact the upper edge of the pit when installed in the pit. .. In other words, the slit is formed at the most end on the upper surface of the main body. Therefore, it is possible to prevent the obstacle of the walking of the person.
Since the downward taper is wider than the downward taper, the downward taper is overlapped with the upward taper of the adjacent lid.

The fourth aspect of the present invention is defined as follows. That is, in the light weight lid for the pit defined 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 as the width of the contact area. is there.
According to the light weight lid for the pit of the fourth aspect defined in this way, the air vent slit exposed in the main body has a predetermined width (the same width as the downward taper) and a predetermined length (the upper surface of the slit). It is the same as the width). By thus defining the shape of the air vent slit, the design of the lid is improved. Further, since the shape of the air vent slit is standardized, the lid can be easily designed for pits having 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 “double” or “same length” in a physically strict sense, It goes without saying that it has a certain margin that is allowed as an industrial product.

The fifth aspect of the present invention is defined as follows. That is,
The lightweight lid for a pit defined in any one of the first to fourth aspects, wherein the reinforcing portion includes a rib formed on the back surface of the main body portion and extending in the width direction of the pit.
According to the lightweight lid for the pit defined in the fifth aspect as described above, the rib is arranged in the width direction of the pit. Therefore, the strength in the width direction is improved, and even if a person rides on the central portion of the lid, the lid hardly deforms.
As such ribs, the ribs can be arranged along the edge having the upward taper and the edge having the downward taper (sixth aspect).

The seventh aspect of the present invention is defined as follows. That is, in the light weight lid for a pit defined in the third or fourth aspect, a rib is provided on the back surface of the main body portion as the reinforcing portion, and the rib hits the upper edge of the pit at a diagonal portion with the air vent slit. The distance between the contact area in contact with the end of the rib is smaller than the height of the rib.
The light weight lid for the pit of the seventh aspect defined in this manner prevents the lid from being flipped over from the pit.
Negative pressure may be applied to the top surface of the lid due to the influence of the moving body or the influence of natural wind. At that time, in the part where the air vent slit is present, the negative pressure is relatively reduced by the movement of the air through the slit as compared with the other parts. Therefore, the negative pressure is an upward force (rotational force) with the portion having the air bleeding slit as a fulcrum to turn up the lid. The axial component of the pit in the upward force is suppressed by the interaction between the upward taper surface and the downward taper surface. On the other hand, the component of the upward force in the width direction of the pit is restricted from moving upward due to the end of the rib (edge of the lower surface) diagonally facing the air vent slit interfering with the inner peripheral surface of the pit. It As a result, even if the lid is lightweight, it is possible to prevent the lid from coming off the pit.

The lid may be subjected to an upward force due to vibration or other unintended external force. This upward external force rarely acts perpendicularly to the lid, and is an upward rotational force with the portion supported by the pit as a fulcrum. That is, a portion other than the portion having the air vent slit may serve as a fulcrum. Therefore, the ends of all ribs should be placed as close as possible to the inner peripheral wall of the pit within the range that does not interfere with the attachment/detachment work. Interfere with the inner wall. That is, the distance between the contact area that contacts 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 (eighth aspect).

A ninth aspect of the present invention is defined as follows, that is, a lid defined in any one of the fifth to eighth aspects, wherein the main body is made of wood, and the main body is provided on the back surface thereof with the lid. A reinforcing layer is attached between the ribs, and the entire surface is covered with the protective material layer. By making the main body of wood in this way, the weight of the lid is significantly reduced. The weight of the lid, for example 15 to 25 kg / ^{m 2,} preferably between 20 kg / ^{m 2.} The strength of the wooden body is supported by the ribs and the reinforcing layer. By covering the entire surface with a protective material layer, weather resistance is secured and fire protection measures are taken.
In the above, the main body portion is formed of a first plywood plate in which the fiber directions of the veneer are orthogonal to each other, and the ribs are formed of a second plywood plate in which the fiber directions of the veneer plate are all aligned in the length direction of the rib, and the reinforcement is performed. The layer is preferably in the form of a sheet or net of aramid fibers (tenth aspect).
In order to reduce the weight of the lid while ensuring sufficient strength to support the walking of a person, it is considered that the combination of each element and the material thereof specified in the tenth aspect is 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 are set to be the same (for example, 10 to 70 degrees), in other words, the upward taper and the downward taper of the adjacent lids face each other. At this time, the surfaces forming each taper are made parallel.

Thereby, the upward taper and the downward taper of the adjacent lids are overlapped with each other without a gap. Therefore, the sealability against rainwater and the like is improved, and it does not hinder the walking of people. Also, by overlapping without a gap, stress concentration when repeated vibration is applied is avoided, and thus durability is improved.
Furthermore, when negative pressure is applied to the upper surface of the lid, the air in the pit preferentially escapes to the outside from 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.

Embodiments of the present invention will be described below with reference to the drawings.
The lightweight lid 10 according to the embodiment is preferably used in a pit arranged along a railroad track, and includes a main body 11 and a reinforcing portion 20.
The main body portion 11 is a rectangular plate material, and an upward taper 12 and a downward taper 13 are formed at opposing long edges. A slit 15 is formed at the edge having the downward taper 13, and the taper disappears at that portion. An area having a predetermined width A1 from the short edge on the back surface of the main body portion 11 becomes a contact area 17 which is placed on the upper edge of the pit 1 and abuts against it.

In the above, it is preferable that the main body 11 is made of wood from the viewpoint of weight reduction. In this example, the veneer is made of the first plywood whose fiber directions are orthogonal to each other. Since a person rides on the main body 10, a load is applied from all directions. Therefore, by using the first plywood having no isotropic load bearing strength, that is, having the same load bearing strength against loads from all directions, cracks and cracks can be surely prevented.
Of course, the material of the main body 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 axial length C1 of the pit 1 is 500 mm, and the thickness is 15 mm, but these dimensions are arbitrarily changed according to the purpose and use of the lid 10. it can.

A taper is formed around the entire long edge of the main body 11. An upward taper 12 is formed on the lower long edge in the drawing, and a downward taper 13 is formed on the upper long edge in the drawing.
When the lid 10 is laid in the pit 1, the upward taper 12 is on the starting 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 and 13 is formed in a plane. The inclination angle of each taper 12 and 13 (angle between the taper 12 and the perpendicular of the main body 11) can be 10 to 70 degrees. In this example, the tilt angle was set to 15 degrees.
The inclination angles of the tapers 12 and 13 are the same. As a result, both can be superposed without any gap.
This taper can be formed over the entire long edge or in part. The inclination angle can be partially changed.

The start end of the air vent slit 15 is in contact with the virtual inner boundary line 18 of the contact area 17. As a result, the air vent slit 15 is formed on the upper surface of the main body portion 11 so as to be closest to the end.
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 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. In this example, the bottom surface of the air vent slit 15 is also an inclined surface parallel to the downward taper 13. As a result, the width of the air vent slit 15 exposed in the main body portion 11 becomes 5 mm. The air vent slit having such a narrow width does not hinder a person's walking.

In the above example, the air vent slit 15 is formed only on the end side of the end edge of the main body 11. The air vent slit 15 can be a mark for determining the position of the lid 10 when the lid is laid.
The air vent slit 15 stabilizes the lid 10. When a negative pressure is applied to the lid 10 after passing a train, the air in the pit 15 is released to the outside through the air vent slit 15. Therefore, the negative pressure can be reduced and the stability of the lid 10 can be secured.

The air vent slit 15 connects the internal space and the external space of the pit 1 to reduce the negative pressure applied to the lid portion. From this viewpoint, the air vent window is not limited to the slit shape. For example, one or two or more independent through holes may be formed. It does not prevent provision of such an air vent window on the edge side having the upward taper.

When the body 11 is made of wood, it is difficult to secure sufficient rigidity considering that a person walks. Of course, even if the main body 11 made of wood is thickened, the rigidity can be secured, but the use of thick wood means that it is heavy and the material cost is high, which is not realistic.
Therefore, in this example, the reinforcing portion 20 is provided on the back surface of the main body 11 made of thin plywood. The reinforcing portion may be provided on the surface or inside of the main body 10.

The reinforcing portion 20 in this example includes ribs 21 and 23 and a reinforcing layer 25.
The ribs 21 and 23 are attached to the back surface of the main body 10 along the edges having the upward taper 12 and the downward taper 13. The ribs 21 and 23 are preferably arranged as close as possible to the upward taper 12 and the downward taper 13, respectively. As a result, each taper deformation is suppressed, and the joining of the both is stabilized.
When attaching the rib 21 (23), it is preferable to provide a groove 27 on the back surface of the main body 10 (see FIG. 2) and force the rib 21 (23) into the groove 27 together with an adhesive.

In this example, the ribs 21 and 23 are provided parallel to the edges having the respective tapers 12 and 13, but the ribs may be provided obliquely with respect to these edges. You may provide three or more ribs.
The ribs 21 and 23 are preferably made of second plywood in which the fiber directions of the single plate are all aligned in the length direction of the rib. The arrangement direction of the fibers is parallel to each taper 12 and 13.
The ribs 21 and 23 are not limited to the second plywood, and synthetic resin or metal pipe can be used. In addition, avoid using conductive or magnetic metal in facilities affected by strong magnetic fields.

The rib 21 (same for the rib 23) is preferably as long as possible in length B2 from the viewpoint of reinforcing the main body portion 10 more strongly. In this example, the width B1:1000 mm of the main body 11 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 end portion of the rib 21 does not interfere with the pit 1 when the lid 10 is attached or detached and does not hinder the attachment and detachment work.
On the other hand, when a negative pressure is applied to the upper surface of the lid 10 including the air vent slit 15, a rotational force 30 is applied with the periphery of 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 and prevents the lid 10 from coming off. Therefore, the distance L1 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 made smaller than the height L2 of the pit 1. Preferably, L1 is half or less than L2.

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

The entire main body 11 and the reinforcing portion 20 are covered with a protective material layer. In this example, a polyurea resin was used as the protective material layer and was applied by a spray method so as to have an average thickness of 1 mm or more. If the protective material layer has weather resistance (water resistance, heat resistance, light resistance) and flame resistance, general flame-retardant resins such as fluororesin and polyphenol resin can be adopted in addition to polyurea.
It is preferable that the entire surface of the main body 11 or a part thereof be subjected to a slip prevention process. One example of the non-slip process is silica sand spraying.

The lid of the embodiment configured as described above satisfies the following specifications.
Loading weight: 300 kgf/m ² or more Displacement amount: 5 mm or less when loading weight Weight: 10 kg/sheet Flame resistance: UL standard V0

As described above, this lid is entirely made of a non-conductive and non-magnetic material. Therefore, it can be applied to facilities such as electromagnetic environment in infrastructure.
This lid can be applied to pits installed along highways and runways as well as railway lines.
When pits are increasingly required to be installed on general roads where automobiles are becoming autonomous, they are also used as lids.

Examples of infrastructure include substations and other electric power facilities. The present invention can be applied as a lightweight lid for a cable pit provided in such a power facility.
That is, another aspect of the present invention is defined as follows.
(1) A lightweight lid for the pit,
A rectangular flat plate-shaped main body,
A reinforcing portion provided on the main body,
A lightweight lid for a pit, in which an upward taper is provided on one of a pair of opposite edges in the main body portion, and a downward taper is provided on the other side.
(2) The lightweight lid according to (1), wherein the main body portion is provided with an air vent slit only in a part 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 center side from the contact area that abuts 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 formed 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 as the width of the contact area.
(5)
The lightweight lid according to any one of (1) to (4), wherein the reinforcing portion includes a rib formed on a back surface of the main body portion and extending in a width direction of the pit.
(6)
The lightweight lid according to (5), wherein the rib is formed along each of the pair of edges.
(7)
A rib is provided on the back surface of the main body portion as the reinforcing portion, and a distance between an end portion of the rib and an abutting region that comes into contact with an upper edge of the pit in a portion diagonal to the air vent slit is more than a height of the rib. The lightweight lid according to (3) or (4), which is small.
(8)
The lightweight lid according to any one of (4) to (6), wherein a distance between an area of the back surface of the main body portion that contacts the upper edge of the pit and one end of the rib is smaller than a height of the rib.
(9)
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. (5) to (8) Lightweight lid.
(10)
The main body is composed of a first plywood in which the fiber directions of the single plate are orthogonal,
The rib comprises a second plywood in which the fiber directions of the veneer are all aligned in the length direction of the rib,
The lightweight lid according to (9), wherein the reinforcing layer is made of a net of aramid fiber.
(11)
The inclination angle of the upward taper and the inclination angle of the downward taper are the same,
The lightweight lid according to any one of (1) to (10).
(12)
The lightweight lid for a pit according to any one of (1) to (11), having a weight of 15 to 20 kg/m ² , preferably 20 kg/m ² .

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

Claims (12)

A lightweight lid for the pit that is placed along the moving path,
A rectangular flat plate-shaped main body,
A reinforcing portion provided on the main body,
An upward taper is provided on one of a pair of opposing edges in the main body, and a downward taper is provided on the other side.
In the laid state of the lid, with the moving direction of the moving body on the moving path as a reference, the upward taper is located on the starting end side and the downward taper is located on the terminal end side.
Lightweight lid for the pit. The lightweight lid according to claim 1, wherein the main body portion is provided with an air vent slit only on a part of the edge provided with the downward taper. The main body portion is provided with an air vent slit on the downward tapered edge, and the air vent slit is directed toward the center side from the contact area that abuts on the upper edge of the pit on the back surface of the main body portion toward the center side and the downward direction. The lightweight lid according to claim 1, which is formed wider than the taper. The lightweight lid according to claim 3, wherein the width of the air vent slit is twice the width of the taper, and the length thereof is the same as the width of the contact area. The lightweight lid according to any one of claims 1 to 4, wherein the reinforcing portion includes a rib extending in a width direction of the pit formed on the back surface of the main body portion. The lightweight lid according to claim 5, wherein the rib is formed along each of the pair of edges. A rib is provided on the back surface of the main body portion as the reinforcing portion, and a distance between an end portion of the rib and an abutting region that comes into contact with an upper edge of the pit in a portion diagonal to the air vent slit is more than a height of the rib. The lightweight lid according to claim 3 or 4, which is small. The lightweight lid according to any one of claims 4 to 6, wherein a distance between a region of the back surface of the main body portion that contacts the upper edge of the pit and one end of the rib is smaller than a height of the rib. The lightweight body according to claim 5, wherein the main body is made of wood, and 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 composed of a first plywood in which the fiber directions of the single plate are orthogonal,
The rib is composed of a second plywood in which the fiber directions of the single plate are all aligned in the length direction of the rib,
The lightweight lid according to claim 9, wherein the reinforcing layer is formed of a sheet or net of aramid fiber. The inclination angle of the upward taper and the inclination angle of the downward taper are the same,
The lightweight lid according to any one of claims 1 to 10. 15~20kg / ^{m 2} weight, preferably 20 kg / ^{m 2,} lightweight lid for a pit according to any one of claims 1 to 11.

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