JP2012122323A - Pit lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pit lid having a simple structure and achieving both weight saving and strength, without being floated up due to buoyant force generated when a train passes through the side of the pit lid.SOLUTION: A pit lid 1 comprises: a top board part 3 in an approximately rectangular plate state; ribs provided on the backside of the top board part 3; handles 5 provided on both ends of the pit lid in the width direction; and the like. On the backside 1b of the pit lid 1, multiple width direction ribs 7a formed in the width direction of the pit lid 1 are formed and multiple longitudinal direction ribs 7b formed in the longitudinal direction of the pit lid 1 and approximately perpendicular to the width direction ribs 7a are formed. In this case, when making portions surrounded by the width direction ribs 7a and the longitudinal direction ribs 7b as spaces, spaces arranged at both ends of the pit lid 1 in the width direction become spaces 11a opening outward in the width direction of the pit lid 1. Namely, the space 11a is formed so as to be opened only to the bottom surface side and one side surface side of the pit lid 1.

Description

  The present invention relates to a pit cover used for a pit provided on the side of a track such as a high-speed railway.

  Conventionally, a pit for laying a signal cable or the like is formed on a track side of a railway or the like. The pit is usually covered with a concrete lid. However, since the concrete pit cover is heavy, work in a limited time such as at night is required, so workability is poor. Therefore, a lighter pit lid is required.

  On the other hand, on the pit cover, it becomes a part where an operator passes for inspection work, transportation of members, and the like. Therefore, high strength is required for the pit cover. That is, the pit cover is required to be both lightweight and high strength.

  As a lightweight pit cover, for example, a plurality of wooden rectangular columnar cover members are arranged in parallel to form a square plate, and there is a connecting means that can be arranged in parallel by providing a water passage gap in each cover member. There is a wooden one-touch sokko cover provided (Patent Document 1).

  In addition, a number of hollow ribs communicating with the entire lid are provided between the top plate and bottom plate of the box-shaped synthetic resin lid, and the weight adjustment material for the lid weight adjustment material is placed in the hollow rib. There is a lid for a side groove in which a hollow portion for material loading is formed and a vent hole penetrating through an integrally joined plate portion of a bottom plate portion and an upper plate portion is provided (Patent Document 2).

  Further, the lid is provided with an excessive internal pressure release valve, the lid is provided with an annular stepped portion and a circular opening at the center thereof, and the excessive internal pressure release valve is an annular lower valve member having an opening, There is a lid with an excessive internal pressure release valve composed of a disk-shaped upper valve member and a rod-shaped member that connects the annular lower valve member and the disk-shaped upper valve member (Patent Document 3).

  Further, there is a synthetic resin pit lid that is placed on the stepped portions on both edges of the upper opening of the pit and has an air passage portion communicating with the outside from the inside of the pit to the stepped portion (Patent Document 4).

JP 2005-30199 A Japanese Patent Application Laid-Open No. 09-312922 JP 2008-285845 A Utility Model Registration No. 3007971

  On the other hand, wind pressure or the like acts on the lid of the pit provided on the side of the track such as a railway when the train passes. 12A and 12B are diagrams showing a pit 101 laid on the side of the track 100 and a pit cover 103 provided on the pit. FIG. 12A is a plan view, and FIG. 12B is a plan view of FIG. It is XX sectional drawing. A train travels on the track 100. When a train travels on the track 100, a pressure change occurs in the vicinity of the pit 101 beside the track due to wind pressure accompanying the travel of the train.

  Specifically, with a certain point as a reference, the pit lid 103 is initially placed on the pit 101 only by its own weight due to gravity. From this state, when the train approaches the point, the positive pressure (force in the direction of pressing the cover downward) gradually increases against the pit cover 103, and the pit cover 103 is pressed toward the pit 101. It is done. Thereafter, from the stage where the train passes through the point, the pressure suddenly changes to negative pressure (force in a direction to lift the lid upward), and the pressure inside the pit 101 becomes larger. Then, after the train has completely passed, the negative pressure suddenly disappears, the working force that lifts the lid upward due to the pressure difference between the top and bottom of the pit lid disappears, and the acting force on the pit lid 103 settles only on gravity .

  Since such a pressure change accompanying the passage of the train also depends on the speed of the train, the pit 101 and the pit cover 103 laid on the side of the higher-speed train track 100 have a greater buoyancy and the like. Works. However, as described above, the lightweight pit cover 103 considering workability may not be able to resist the buoyancy when passing through the train, and the pit cover 103 may be blown off. A big accident will be caused by hitting or scattering along the line.

  On the other hand, in a method like patent document 1, it was made into the structure which can be connected so that adjustment of length is possible only as a wooden lid, and only formed a water flow gap for prevention of corrosion of a wooden lid. It is not possible to counter the buoyancy as described above. In particular, since the strength of the lid itself is reduced by forming a hole for draining water to prevent corrosion, it is necessary to use a thick member for walking on the pit and transporting objects. There is a problem that the effect of weight reduction is small.

  That is, with the lid of Patent Document 1, it is difficult to achieve sufficient weight reduction and strength, and no consideration is given to preventing the lid from lifting.

  Moreover, since the lid for a side groove described in Patent Document 2 fills a hollow portion with a weight adjusting agent, it requires man-hours, and it is necessary to transport the weight adjusting agent when laying the lid. The effect of improving is small. In addition, since the weight adjusting agent is filled inside, when performing the internal inspection after laying, the weight of the lid is heavy and the workability is not high, and many vents are formed in the upper plate part. There is a risk of lowering the strength of the upper plate. In addition, since the vent is oriented in the vertical direction, the vent may be clogged with dust or the like. In addition, since the ventilation direction is a direction perpendicular to the upper plate portion and is perpendicular to the direction of receiving the wind pressure when passing through the train (the direction from the track side to the pit), there is a problem that the ventilation efficiency is not high.

  That is, since the lid of Patent Document 2 considers prevention of lifting, as a result, it is difficult to reduce the weight in consideration of workability, and it is difficult to ensure sufficient strength.

  The lid with an excessive internal pressure release valve described in Patent Document 3 is provided with a release valve at the center of the lid, but the mechanism is complicated and the cost of the lid itself increases. Moreover, since it has an operation | movement part, valve operation worsens with time, and there exists a possibility that a part of internal pressure release may become impossible by this. Moreover, since the release valve is provided near the center of the lid, there is a problem that the strength of the lid is reduced. Particularly in the vicinity of the release valve, a large hole is formed in the lid, so that the strength of the lid body is reduced, and if a force is applied to the upper part of the release valve itself, the valve may be damaged. However, if the valve itself is reinforced, the weight of the valve itself increases, and it becomes difficult not only to obtain sufficient internal pressure release characteristics, but also results in an increase in the weight of the lid.

  In other words, the lid of Patent Document 3 sacrifices the strength, weight, and cost of the lid itself because it intends to release the internal pressure. It is difficult.

  Moreover, although the pit cover described in Patent Document 4 is provided with an air flow path that communicates the inside and outside of the pit at both edge portions, the weight of the lid is not sufficient. Further, by forming the notch portions only on both side portions, there is a possibility that stress concentration occurs at the boundary portion of the thickness change portion with respect to the force from above the lid. Therefore, the strength is not sufficient.

  In addition, notches are formed on both edges and the lid has a shape corresponding to the step at the opening edge of the pit top, making it difficult to follow fluctuations (accuracy) in the pit opening width. There is a possibility that the air flow path is blocked by the side wall of the opening edge.

  In addition, although there is no detailed description about the shape of the air flow path, even if considering the drawings and the like, it is difficult to ensure a sufficient flow path cross-sectional area for the air flow, so the pressure loss is large, There is a possibility that the effect of reducing the pressure difference cannot be obtained sufficiently. However, if the notch is expanded in the direction of the center of the lid to secure the cross-sectional area of the flow path, as described above, the stress concentration portion shifts in the direction of the center of the lid, and as a result, against the upper load of the lid. It becomes difficult to obtain sufficient strength.

  As described above, the conventional lid for pits has a simple structure and achieves both weight reduction in consideration of workability and efficiency of laying work and inspection work and high strength against load from above. It is not possible to reliably prevent the lid from being blown off due to the buoyancy associated with the pressure difference between the inside and outside of the pit.

  The present invention has been made in view of such a problem, and has a simple structure, which achieves both weight reduction and strength, and has a pit cover that does not lift due to buoyancy generated when a train passes by the pit side. The purpose is to provide.

  In order to achieve the above-described object, the present invention is a pit lid, which is formed on the top plate portion and the back surface of the top plate portion, and in the width direction and the longitudinal direction of the top plate portion, A width direction rib and a length direction rib integrally formed so as to be orthogonal to each other, and a pair of notch-shaped handle portions, at both ends in the width direction of the pit cover, at both ends of the width direction rib A plurality of first air flow paths in which the space and the outside of the pit lid communicate with each other by opening the space defined by the portion and the longitudinal rib toward the end portion in the width direction of the pit lid. The notch part of the said handle part is a pit cover characterized by becoming a 2nd air flow path which directly connects the back side of the said top-plate part, and the outer side of a pit cover.

  Here, the space defined by the width direction rib and the longitudinal direction rib is a space in which each rib standing on the back surface of the top plate portion is a wall portion and a surface facing the top plate portion is released. The part surrounded by the width direction rib and the longitudinal direction rib is pointed out.

  The width-direction rib and the longitudinal-direction rib are integrally formed perpendicularly to each other in a lattice shape by traversing or longitudinally extending in a straight line to the vicinity of the outer periphery of the top plate portion, and constituting the first air flow path Parts other than both ends of the width direction rib are formed continuously with respect to both ends of the width direction rib, and the top plate is formed by using the parts other than both ends of the width direction rib and the longitudinal rib as wall portions. A plurality of structures that are partitioned into a space in which a surface facing the top plate portion is opened so that five directions are surrounded by the back surface of the top portion and the wall portion are formed vertically and horizontally on the back surface of the top plate portion. It is desirable that

  The notch portion of the handle portion is formed at both end portions in the width direction of the top plate portion, and both the formation direction of the second air flow path and the formation direction of the first air flow path are the pits. It is the width direction of the lid, and it is desirable to be formed in the same direction.

  At least a part of the end surface in the width direction of the pit lid is formed with a channel holding means projecting on both sides of the width direction edge of the top plate portion, and the end of the channel holding means is substantially vertical. It is desirable that a gap is held between the widthwise edge of the top plate and the wall when contacting the wall, and the first air flow path can be prevented from being blocked.

  The end portion of the width direction rib may have a tapered shape that extends downward from the connection portion with the top plate portion, and the flow path holding means is formed at the end portion of the width direction rib. It may be a tapered shape.

  In the back surface of the top plate portion, it is preferable that the handle portion rib is formed so that the width direction rib and the handle portion rib are integrally joined around the notch portion. It is preferable that the handle portion rib is formed so as to surround the notch portion at a distance from the edge portion of the notch portion.

  In the first air flow path, a cross-sectional area formed by cutting the space in the longitudinal direction and formed by the top plate portion and the width direction ribs is on both sides in the width direction of the top plate portion. It is desirable that it becomes larger as it goes to.

  Here, the section when the space is cut in the longitudinal direction is a section when the space is cut in parallel with the longitudinal direction of the pit lid, and is defined by the back surface of the top plate portion and the opposing surfaces of the width direction ribs standing on both sides. It refers to a space formed in an approximately U shape. The cross-sectional area formed by the top plate portion and the width direction rib is a section surrounded by a virtual line connecting the back surface of the top plate portion and the opposite surface of the width direction rib standing on both sides and the top portion of the width direction rib. It is an area and refers to a portion that becomes an air flow path.

  It is desirable that the top plate portion has a convex shape at the center, and the heights of the width direction ribs and the longitudinal direction ribs increase toward the center of the top plate portion.

  It is desirable that the width-direction rib has a width that decreases from the vicinity of the center in the width direction of the top plate portion toward both sides in the width direction. Here, the width of the rib refers to the width at the top of the rib when viewed from the rear surface of the pit lid.

  It is desirable that a thickness of the top plate portion in the first air flow path becomes thinner toward an end portion in the width direction of the top plate portion. That is, the thickness of the top plate portion increases toward the central portion in the width direction.

  A plurality of protrusions are formed outside the side surface on at least one side in the longitudinal rib forming direction, and when the pit cover is installed, a gap is formed by the protrusion between the side surfaces of the adjacent pit cover. It may be possible to form a third air flow path that communicates the back side of the top plate and the outside of the lid.

  According to this invention, since the width direction rib and the longitudinal direction rib which are orthogonal to each other are formed on the back surface of the top plate portion, it is possible to achieve both a high weight reduction effect and strength. In addition, the space surrounded by the width direction rib and the longitudinal direction rib formed at the end of the pit cover in the width direction communicates with the outside of the cover to form an air flow path, eliminating the pressure difference inside and outside the pit. The pit lid can be prevented from rising.

  Moreover, a handle part is formed in the same direction as the air flow path using a rib. Therefore, the laying operation of the pit lid is easy. In addition, since the notch portion that forms the handle portion forms an air flow path that communicates the inside and outside of the pit lid, the pressure difference between the inside and outside of the pit can be more reliably eliminated, and the pit lid can be prevented from rising.

  It is desirable that the width direction of the pit lid is set so as to face the width direction of the pit. This is because if the air flow path is provided from the train track toward the pit direction (direction perpendicular to the pit laying direction), air generated by the traveling of the train can flow more efficiently. Therefore, in the present invention, the air flow path by the rib and the air flow path by the handle are set in the same direction, and this is the width direction of the pit lid, so that the air in the pit can be flowed more efficiently. However, even if the air flow path by the width direction rib and the air flow path by the handle part are formed in directions orthogonal to each other, the efficiency of escaping the air in the pit during train travel is slightly reduced, but it can be used as a lightweight pit lid Needless to say.

  Further, the width direction rib and the length direction rib are integrally formed to cross each other in a straight line up to the vicinity of the outer periphery of the top plate portion and perpendicular to each other in a lattice shape. Further, portions other than both ends of the width direction rib are formed continuously with respect to both ends of the width direction rib constituting the first air flow path, and the portions other than both ends of the width direction rib and the longitudinal direction rib. As a wall portion, a plurality of structures that are partitioned into a space in which the surface facing the top plate portion is opened are continuously and vertically and horizontally formed on the back surface of the top plate portion so that the four directions are surrounded by the wall portion. .

  Therefore, for one width direction rib, the vicinity of both end portions can be used as an element constituting the first flow path, and portions other than both end portions (that is, portions requiring higher strength) By forming a space surrounded by the four directions described above, the strength of the lid can be improved. That is, according to the said structure, it is not what formed the rib for the intensity | strength improvement simply, and formed the air flow path in the edge part, but two functions of intensity | strength improvement and flow path formation with respect to the width direction rib. Can be given depending on the part.

  In addition, on the back surface of the top plate portion, the back surface of the top plate portion can be gripped by a slight distance around the handle portion (when a hand is inserted into the handle portion and the back surface of the top plate portion is lifted upward) If the handle rib is provided with a certain level of difference), the workability is excellent, and the strength reduction due to the notch shape of the handle can be suppressed. Further, by forming the handle portion rib integrally with the width direction rib, high strength can be secured without causing stress concentration.

  In addition, by gradually reducing the width of the width direction rib from the center of the pit cover toward both edges, when the pit cover is installed and a load is applied from above, it is high in the vicinity of the center where the strength is most required. While ensuring the strength, it is possible to reduce the weight by removing unnecessary meat on both sides.

  Moreover, with the change in the width of the width direction ribs, the distance between the width direction ribs becomes wider from the center of the lid toward both edges. Therefore, the flow path cross-sectional area of the air flow path (first air flow path) constituted by the width direction ribs can be increased toward the end. Therefore, the pressure loss of the air flow in the air flow path can be suppressed, and the air can flow more efficiently. In addition, the contribution ratio of the channel cross-sectional area to the pressure loss is large. For example, when the air flow is not disturbed (laminar flow), the pressure loss increases in proportion to the square of the cross-sectional area, which is defined by the Hagen-Poiseuille equation. .

  Moreover, the cross-sectional area of the air channel mentioned above can be ensured by making the thickness of the top plate part in the air channel thinner toward the end in the width direction of the top plate part. Therefore, air can be flowed more efficiently.

  Moreover, the center part of a pit cover is made into convex shape, and the intensity | strength with respect to the load from the upper direction of a top-plate part can be heightened by an arch effect by making it low toward the edge part of a longitudinal direction and the width direction. Also, according to the shape of the top plate, the height of the width direction rib and the longitudinal direction rib is increased toward the center of the top plate, so that higher strength is ensured particularly in the central portion where the stress becomes large. can do.

  In addition, the width of the pit cover changes slightly when the pit cover is installed in the pit by making the end of the width direction rib (end of the pit cover in the width direction) tapered downward. Even so, the side surface of the pit lid is not blocked, and the air flow path can be secured reliably.

  The pit cover of the present invention is a pit cover in which the lower end position of the width direction rib and the longitudinal direction rib is substantially constant, no step is formed on the lower surface side (rib) of the pit cover, and the lower surface is substantially flat. . Therefore, even if the pit shape is not constant and the width of the pit lid installation part is narrow, if the pit lid is cut to a predetermined width and used, the pit lid can be installed and the above-described effects Can be obtained.

  According to the present invention, it is possible to provide a pit cover that has a simple structure, achieves both weight reduction and strength, and does not lift up due to buoyancy generated when a train passes through the pit side.

It is a figure which shows the pit cover 1, (a) is a surface perspective view, (b) is a back surface perspective view. The top view of the pit cover 1. FIG. The bottom view of the pit cover 1. FIG. 2A and 2B are views showing the pit lid 1, in which FIG. 2A is a rear view of the pit lid 1, and FIG. 2B is a left side view of the pit lid 1. 3A and 3B are views showing a pit cover 1, in which FIG. 3A is a cross-sectional view taken along line CC in FIG. 3, and FIG. The enlarged view which shows the shape of the width direction rib 7a and the longitudinal direction rib 7b. Sectional drawing which shows the use condition of the pit cover 1. FIG. The Q section enlarged view of Drawing 7 (a). The bottom view of the pit cover 10. FIG. It is a figure which shows the other flow-path holding means of the pit cover 10, (a) is sectional drawing which shows a use condition, (b) is the W section enlarged view of (a). The bottom view of the pit cover 20. FIG. The figure which shows the arrangement | positioning of a pit, and the shape of the conventional pit cover.

  Hereinafter, the pit cover 1 according to the embodiment of the present invention will be described. 1A and 1B are diagrams showing a pit lid 1, in which FIG. 1A is a front perspective view and FIG. 1B is a rear perspective view. FIG. 2 is a plan view of the pit lid 1 and FIG. 3 is a bottom view of the pit lid 1.

  The pit lid 1 includes a substantially rectangular plate-shaped top plate portion 3, ribs provided on the back side of the top plate portion 3, handle portions 5 provided at both ends in the width direction, and the like. The pit lid 1 is made of resin and is not specified if it has a certain level of strength and durability, but it is made of recycled plastic (polyethylene, polypropylene, etc.), flame retardants, etc. in consideration of workability such as cost and weight reduction. A resin composition can be used.

  On the surface 1a side of the pit lid 1, fine irregularities are formed as necessary for the purpose of preventing slipping. This unevenness also functions as a rib and contributes to improving the strength of the pit lid. In addition, as the pit cover 1 of this invention, the pattern (uneven | corrugated shape, arrangement | positioning, etc.) of the surface 1a is not restricted to the illustrated example.

  On the back surface 1b side of the pit cover 1, a width-direction rib 7a formed in the width direction of the pit cover 1 (left-right direction in FIG. 3) and the longitudinal direction of the pit cover 1 (up-down direction in FIG. 3) A plurality of longitudinal ribs 7b substantially perpendicular to the widthwise ribs 7a are formed. That is, the width direction ribs 7a and the length direction ribs 7b are integrally formed perpendicularly to each other in a lattice shape by traversing or vertically cutting to the vicinity of the outer periphery of the top plate portion. The tops of the width direction ribs 7a and the length direction ribs 7b (on the side opposite to the top plate part 3 and on the lower surface side) are formed on the same plane. In addition, the detailed shape of the width direction rib 7a and the longitudinal direction rib 7b is mentioned later.

  Here, a portion surrounded by the width direction rib 7a and the length direction rib 7b (the width direction rib 7a and the length direction rib 7b are used as wall portions, the four directions of the surrounding wall portions, and the back surface 1b of the top plate portion 3) The region surrounded by all five directions) is defined as a space 11. That is, the space 11 is a space that opens only on the bottom surface side of the pit lid 1. Further, the spaces arranged at both ends in the width direction of the pit lid 1 are spaces 11 a that open to the outside in the width direction of the pit lid 1. That is, the space 11a is formed so as to open toward the bottom of the pit lid 1 and the end on one side.

  Handle portions 5 are provided on both sides of the pit lid 1 in the width direction. The handle portion 5 has a shape in which a part of the end portion of the top plate portion 3 is notched and is notched in plan view. The handle 5 is a part having the pit lid 1 by hand when the pit lid 1 is laid.

  FIG. 5A is a cross-sectional view of the pit lid 1, and is a cross-sectional view taken along the line CC in FIG. On the back side of the handle portion 5, a step portion 5a for holding the pit lid 1 by hand is formed, and a handle portion rib 7c is provided so as to surround the periphery of the step portion 5a. That is, the handle portion rib 7c is formed at a predetermined distance from the notch portion (via the step portion 5a). In the handle portion 5, the region below the pit lid 1 (top plate portion 3) communicates with the region outside the pit lid 1 through the notch.

  As shown in FIG. 3, the handle portion rib 7c is formed integrally with the width direction rib 7a, and as a result, the rib around the handle portion is opened only at the bottom portion surrounded by all five directions. It can be set as the rib structure where the circumference | surroundings which form space are enclosed. In the example of FIG. 3, both end portions of a total of three width direction ribs 7a, that is, a width direction rib 7a located in the center portion in the longitudinal direction of the pit lid 1 and a pair of adjacent width direction ribs 7a are formed as handle portion ribs 7c. They are joined together so as to merge. By integrating the width direction rib, 7a, and the handle portion rib 7c, it is possible to suppress a decrease in strength due to the formation of the notch. In addition, the height of the handle portion ribs 7c can be formed lower than the heights of the width direction ribs 7a and the longitudinal direction ribs 7b, and the ribs can be smoothly connected to form steps in the ribs. By doing in this way, while being able to grasp a handle easily, the air channel mentioned below can be secured more certainly.

  FIG. 4A is a rear view (longitudinal side view) of the pit lid 1, and is a view taken in the direction of arrow A in FIG. The top plate portion 3 of the pit lid 1 is formed in a convex shape upward with the top plate center 9 as the top. That is, the pit lid 1 is formed so that the top plate center 9 is the highest and becomes lower as it goes to the end of the top plate portion 3.

  The taper angle formed on the top surface of the top plate portion 3 may be about 1 °. For example, if the pit cover 1 has a shape of about 500 mm square, the difference in height between the top plate center 9 and the longitudinal end portion. (F in the figure) may be about 5 mm. As described above, since the bottom surfaces of the width direction ribs 7a and the longitudinal direction ribs 7b coincide with each other, the height of each rib increases in accordance with the shape of the top plate portion 3 as it goes to the top plate center 9 of the pit lid 1. Become.

  Both side portions of the pit lid 1 in the width direction (both ends of the width direction rib 7a) are tapered so as to expand toward the bottom from the top plate portion 3 side. That is, a taper that is a flow path holding means is formed so that the lower surface side of the pit lid 1 protrudes in the width direction with respect to the width direction edge of the top plate portion 3. The taper angle (G in the figure) may be about 5 °, for example. Further, a plurality of protrusions 2 are formed on the outer surfaces of both sides in the longitudinal direction of the pit lid 1 in order to prevent the pit lid from rising due to thermal expansion when the pit lids are continuously arranged in the longitudinal direction. In addition, the protrusion 2 may be formed on either the front side or the back side of both sides in the longitudinal direction of the pit lid, or may be formed on both the front and back sides. For example, when forming only on the back surface of the pit cover, the front surface of the pit cover 1 is different from the back surface only in the presence or absence of the protrusions 2, and the other configurations are all the same.

  FIG. 4B is a left side view (side view in the width direction) of the pit lid 1, and is a view taken in the direction of arrow B in FIG. The right side view of the pit lid 1 is the same, and the left and right sides are represented as objects. As described above, the top plate portion 3 of the pit lid 1 is formed in a convex shape upward with the top plate center 9 as the top. The taper angle may be about 1 °. For example, if the pit cover 1 has a shape of about 500 mm square, the height difference (E in the figure) between the top plate center 9 and the width direction end is about 5 mm. I just need it.

  As described above, the handle portion 5 and the space 11a are opened in the lateral direction of the pit lid 1 in the width direction. Therefore, the area under the pit cover 1 (top plate part 3) and the area outside the pit cover 1 communicate with each other in the width direction side portion of the pit cover 1.

  FIG. 5B is a cross-sectional view of the pit cover 1, and is a cross-sectional view taken along line DD in FIG. In the space 11a, the thickness of the top plate portion 3 gradually decreases as it goes to both ends of the pit lid 1 in the width direction. That is, the ceiling on the opening side of the space 11a (in the end portion direction of the pit lid 1) with respect to the thickness (H in the drawing) of the top plate portion 3 at the end portion on the back side of the space 11a (in the center direction of the pit lid 1). The thickness (I in the figure) of the plate portion 3 is reduced.

  For example, if the thickness of the top plate portion 3 (H in the figure) is about 22 mm, the thickness (I in the drawing) of the width direction end of the top plate portion 3 may be about 11 mm. That is, in the space 11a that communicates the area below the pit lid 1 (top plate portion 3) and the area outside the pit lid 1, the height of the space 11a increases toward the end.

  FIG. 6 is an enlarged view of the width direction rib 7a and the longitudinal direction rib 7b, and is an enlarged view of a portion V in FIG. Longitudinal ribs 7b have a smaller width (U in the figure) than those arranged on both sides in the width direction with respect to the width (T in the figure) passing through the center of the pit lid 1. That is, in the example of FIG. 3, although three longitudinal ribs 7b are formed in total, the width of the central longitudinal rib 7b is larger than the widths of the other longitudinal ribs 7b. For example, if the width of the central longitudinal rib 7b is about 24 mm, the width of the other longitudinal rib 7b may be about 20 mm.

  Similarly, the width of the width direction rib 7a decreases as it goes from the center of the pit lid 1 to the end. That is, the width direction rib 7a has a width at the end in the width direction of the pit lid 1 (M in the figure) with respect to the width (L in the figure) of the center of the pit lid 1 (joint portion with the central longitudinal rib 7b). ) Is smaller. For example, if the width of the central portion of the width direction rib 7a is about 24 mm, the width of the end portion may be about 15 mm. Note that the thickness of the width direction rib may be constant without changing to a tapered shape.

  In addition, since the width of the width direction rib 7a decreases as it goes to the end in the width direction, the width of the space 11a (the length in the longitudinal direction of the pit cover and the interval between the width direction ribs) is the same as that of the pit cover 1. It gradually increases from the central direction toward the end. That is, the width of the space 11a is larger at the end portion in the width direction of the pit lid 1 (J in the figure) than the width on the center side of the pit lid 1 (K in the figure).

  As described above, in the space 11a, the thickness of the top plate portion 3 is reduced and the width of the space 11a is increased at the same time as it goes to the opening side (the end in the width direction of the pit lid 1). Therefore, when the space 11a is cut in the longitudinal direction, the cross-sectional area of the U-shaped portion (space 11a) surrounded by the top plate portion 3 (back surface 1b) and the width direction rib 7a is the width direction of the pit lid 1 It grows toward the end.

  Next, the use state of the pit lid 1 will be described. 7 is a cross-sectional view of the pit 13 with the pit lid 1 installed. FIG. 7 (a) is a diagram corresponding to the cross section along the line DD in FIG. 3, and FIG. 7 (b) is a cross-sectional view of FIG. It is a figure corresponding to CC line cross section. The pit 13 is laid on the side of the track as shown in FIG. The pit lid 1 is installed such that the longitudinal direction of the pit lid 1 corresponds to the longitudinal direction of the pit 13, and a plurality of pit lids 1 are arranged in the longitudinal direction. That is, the width direction of the pit lid 1 corresponds to the width direction of the pit 13.

  By installing the width direction of the pit lid 1 in the width direction of the pit 13, an air flow path to be described later is directed from the train track toward the pit 13 (direction perpendicular to the pit laying direction). This is because the air that is provided can more efficiently flow air generated by the traveling of the train.

  A step 15 is formed at the upper edge of the U-shaped pit 13. The pit lid 1 is installed so as to straddle the step 15 on both sides. That is, the interval between the side surfaces of the step 15 on both sides is set larger than the width of the pit lid 1.

  When a train passes on a track installed on the side with the pit lid 1 laid, it is affected by the wind accompanying the passage of the train (for example, N direction in the figure). In particular, when the pit 13 is provided along the track, the influence of the wind on the direction perpendicular to the passing direction of the train is large. At this time, as described above, there may be a difference in atmospheric pressure between the inside and outside of the pit 13.

  Specifically, when the speed of the train is about 300km / h, the wind speed in the laying direction of the pit, which is almost parallel to the track of the train, is 2.7m / s, while the pit is perpendicular to the pit laying direction. The wind speed with respect to the laying direction of the lid was 11 m / s, which was about 4 times the wind speed with respect to the pit laying direction.

  As shown in FIG. 7A, the space 11 a of the pit lid 1 is open to the side of the pit lid 1. Further, a gap is formed between the side surface of the step 15 and the pit lid 1. For this reason, the air easily flows under the pit cover 1 (inside the pit 13) via the gap between the step 15 and the pit cover 1 against the wind from the side, and the pressure of the air in the pit Can be reduced (in the direction of arrow O in the figure).

  Similarly, the air inside the pit 13 can easily flow to the outside via the gap between the step 15 and the pit lid 1 (in the direction of arrow P in the figure). That is, a plurality of flow paths (O and P in the drawing) that are first air flow paths are formed in the width direction end of the pit lid 1 in the width direction. For this reason, the pressure difference between the inside and outside of the pit 13 can be eliminated instantaneously.

  Here, the part of the width direction rib 7a located further outside the longitudinal direction rib located on the outermost side in the width direction of the pit lid 1 is defined as “both ends of the width direction rib 7a”. In Fig.7 (a), the site | part of the both ends side rather than the longitudinal direction rib 7b other than the center longitudinal direction rib 7b becomes the both ends of the width direction rib 7a. Further, in FIG. 7A, a portion sandwiched by the longitudinal ribs 7b other than the central longitudinal rib 7b is referred to as “other than both ends of the widthwise ribs 7a”.

  As described above, since the width direction rib 7a is continuously formed on a straight line, the portions other than the both ends of the width direction rib 7a with respect to the both ends of the width direction rib 7a constituting the first air flow path are It is formed continuously. At this time, if the portions other than both end portions of the width direction rib 7a and the longitudinal direction rib 7b are wall portions, as described above, the space 11 is formed so as to be surrounded by the top plate and the four direction wall portions. That is, the back surface of the top plate portion 3 is partitioned by a plurality of spaces 11, and a plurality of the structures are formed continuously in the vertical and horizontal directions on the back surface of the top plate portion 3.

  By doing in this way, with respect to one width direction rib 7a, the vicinity of both ends of the width direction rib 7a is an element constituting the air flow path, and the pit cover 1 is a portion that requires higher strength. The portions other than both end portions of the width direction rib 7a can improve the strength of the lid by forming a plurality of the spaces surrounded by the above-mentioned four directions vertically and horizontally.

  FIG. 8 is an enlarged view of a portion P in FIG. As described above, the end of the width direction rib 7a (the end of the pit lid 1 in the width direction) is tapered so as to expand downward. The pit cover 1 is laid at a predetermined interval with respect to the side of the step 15, but the pit cover 1 is installed against the side (substantially vertical wall) of the step 15. However, the air flow path P is not blocked. Therefore, the air flow path can be secured regardless of the laying state of the pit lid 1.

  In order to obtain such an effect, when the pit lid 1 is pressed against the wall portion and installed (that is, when the taper-shaped maximum width portion which is the flow path holding means is brought into contact with the wall portion). It is necessary to secure a gap between the edge in the width direction of the top plate 3 and the wall. For example, since the width of the portion of the pit that supports the pit lid is about 50 mm, it is desirable to set the gap to about 10 mm to 15 mm from the viewpoint of stability when the pit lid is laid and securing the gap. This is because if the gap is too small, the flow path holding effect cannot be sufficiently obtained, and if the gap is too large, there is a possibility that foreign matter or the like enters the pit.

  Similarly, as illustrated in FIG. 7B, the handle portion 5 is open to the side (upper side) of the pit lid 1. A gap is formed between the side of the step 15 and the pit lid 1. For this reason, air can easily flow below the pit lid 1 (inside the pit 13) via the gap between the step 15 and the handle portion 5 of the pit lid 1 against the wind from the side ( Arrow R direction in the figure).

  Similarly, the air inside the pit 13 can easily flow to the outside via the gap between the step 15 and the pit lid 1 (in the direction of arrow S in the figure). That is, the handle portion 5 is formed with a flow path (R, S in the figure) that is a second air flow path that directly communicates inside and outside the pit in the width direction. For this reason, the pressure difference between the inside and outside of the pit 13 can be eliminated instantaneously.

  In addition, since the handle part 5 is formed in a notch shape, the flow path is not blocked even when the pit cover 1 is abutted against the side surface of the step 15, and the pit cover 1 is not closed from the handle part 5. Since a flow path through which air escapes is formed immediately above, it is effective.

  As described above, according to the present embodiment, the back surface of the pit lid 1 has a rib structure, and the width direction rib 7a and the longitudinal direction rib 7b are formed. For this reason, there is no useless meat, it is lightweight and high strength can be obtained. In addition, since the space 11a is open to the end of the pit lid 1 in the width direction, the first air flow path is formed when installed on the pit 13 to eliminate the pressure difference between the inside and outside of the pit. Can do.

  In addition, by providing the handle portion 5 and forming the handle portion 5 in a notch shape, a second air flow path is formed when installed in the pit 13, and the pressure difference inside and outside the pit is more reliably eliminated. be able to. Also, by providing protrusions on at least the front or back of both sides in the longitudinal direction of the pit cover, when the pit cover is continuously arranged in the longitudinal direction, the side part of the pit cover and the protrusions or protrusions come into contact with each other, Since a gap is formed at the contact portion and this becomes the third flow path, in addition to the second flow path, the third flow path also has an effect of preventing lifting.

  Also, the end of the width direction rib 7a (the end of the pit cover 1 in the width direction) is tapered, and the air flow path is also present when the end of the pit cover 1 in the width direction is abutted against the wall of the installation part. A flow path holding means for preventing the blockage is formed. For this reason, even if it is a case where it installs so that the pit cover 1 may contact the level | step difference 15 side surface, a 1st air flow path is not obstruct | occluded.

  In addition, as the flow path holding means, not only the widthwise ribs are tapered toward the bottom, but also when the widthwise end of the pit lid is brought into contact with the wall, Other forms may be used as long as the gap can be maintained.

  FIG. 9 is a bottom view showing the pit lid 10. In the pit lid 10, the end of the width direction rib 7 a is not tapered, and a protrusion 12 is formed on a part of the end. That is, the protrusion 12 is formed so as to protrude outward from both edges in the width direction of the top plate portion 3.

  FIG. 10A is a diagram showing a state in which the pit lid 10 is installed in the pit 13, and FIG. 10B is an enlarged view of a W portion in FIG. 10A. As described above, the pit cover 10 is formed such that a part or the whole of the end portion of the width direction rib 7a protrudes outward from both edges in the width direction of the top plate portion 3 outward. The Therefore, the end of the pit lid 10 in the width direction is the tip of the protrusion 12.

  By doing in this way, even if it is a case where the pit cover 10 is installed in the pit 13 and at least one end part is in contact with the wall part in the installation part of the pit 13, it is a plurality of first air flow paths. The flow paths (O and P in the figure) are not blocked. That is, part or all of the width direction ribs 7a can be caused to project in the width direction, thereby functioning as a channel holding means for preventing the channel from being blocked. The shape and arrangement of the protrusions 12 are not limited to the illustrated example. For example, the protrusion 12 may be formed at a part of the end portion in the width direction, or may protrude entirely.

  Further, since the handle portion 5 has a notch shape and opens above the pit lid 1, the second flow path is blocked even when the pit lid 1 is installed so as to contact the side surface of the step 15. There is no. Therefore, a flow path can be ensured reliably.

  In addition, when the first air flow path and the second air flow path are formed in the same direction of the pit lid 1 and laid in the pit 13, the direction from the track side where the train travels to the pit (the travel direction of the train) Therefore, the air flow between the inside and outside of the pit is smooth, and the pressure difference between the inside and outside of the pit can be reliably eliminated. That is, in the present invention, since the first air flow path by the width direction rib 7a and the second air flow path by the handle portion 5 are set in the same direction and this is set to the width direction of the pit lid 1, the pits are more efficiently used. Inside air can flow. Further, since the air flow path is not formed at the center in the width direction of the pit, the strength of the pit lid 1 is not reduced due to the formation of the air flow path.

  Further, in the space 11a, the thickness of the top plate 3 and the width of the width direction rib 7a become smaller toward the end of the pit lid 1 in the width direction. Area) increases toward the end in the width direction. Therefore, the pressure loss of the air flowing through the air flow path is reduced, and the flow of air inside and outside the pit can be ensured more reliably.

  Further, with respect to the load from above the pit lid 1, the greatest stress is generated at the center of the pit lid 1, but the rib formed on the pit lid 1 has a larger width (thickness) toward the center of the pit lid 1. Since the width (thickness) decreases toward the end, extremely high strength can be ensured without causing excessive strength or weight increase.

  Further, since the center of the pit lid 1 is convex, a high strength can be ensured by the arch effect of the pit lid 1 against the load from above the pit lid 1. At this time, it is possible to prevent a puddle from being formed on the pit lid 1 by a slight taper formed on the upper surface of the pit lid 1.

  Moreover, since the shape of the top plate part 3 is a convex shape and the lower surface of the pit lid 1 (the lower surface of the width direction rib 7a and the longitudinal direction rib 7b) is arranged on the same plane, the height of each rib is pit The center of the lid 1 becomes higher. For this reason, the vicinity of the center of the pit lid 1 can be reliably reinforced.

  Moreover, since the handle part rib 7c is formed in the circumference | surroundings of the handle part 5, while being able to suppress the strength fall by the notch of the handle part 5, the handle part rib 7c and the width direction rib 7a are integrated. Since it is joined, the stress near the handle portion 5 can be reliably transmitted to the width direction rib 7a. For this reason, stress concentration does not occur in the vicinity of the handle portion 5.

  In addition, since the lower surfaces of the pit lid 1 (the lower surfaces of the width direction ribs 7a and the longitudinal direction ribs 7b) are arranged on the same plane, Even if the pit lid 1 cannot be installed, the end in the width direction of the pit lid 1 may be cut. Since the space 11a is open to the width direction end portion side, even if the end portion of the pit lid 1 is cut and removed, an air flow path can be reliably ensured.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, the number of installed width direction ribs 7a and longitudinal direction ribs 7b is not limited to the illustrated example. It is set as appropriate according to the size of the pit lid 1 and the required strength. Moreover, although the width direction and the longitudinal direction showed the example with substantially the same length, the pit cover 1 can also set a longer thing with respect to a longitudinal direction. The size of the pit lid 1 is appropriately set according to the weight or the like at the installation location.

  Moreover, even if the first air flow path by the width direction rib 7a and the second air flow path by the handle portion 5 are formed in directions orthogonal to each other, the efficiency of releasing the air in the pit during train traveling is slightly reduced. Needless to say, it can be used as a lightweight pit lid.

  FIG. 11 is a view showing a pit lid 20 in which the handle portion 5 is formed in the longitudinal direction. The pit lid 20 is disposed at a position where the handle 5 is 90 degrees different from the pit lid 1. Therefore, in the pit lid 20, the handle portion rib 7c is integrally formed by joining not only the width direction rib 7a but also the longitudinal direction rib 7b. When the pit lid 20 is installed in the pit, the handle portion 5 is arranged not at the end of the pit but at the center. Therefore, when the pit lid 20 is used, the handle portions 5 of the adjacent pit lids 20 face each other, and the second flow path is formed at the center of the pit.

1, 10, 20 ......... Pit lid 1a ......... Front surface 1b ......... Back surface 2 ......... Protrusions 3 ......... Top plate portion 5 ......... Handle portion 5a ......... Step portion 7a ......... Width direction Rib 7b ......... Longitudinal rib 7c ... Handle rib 9 ......... Top plate center 11, 11a ......... Space 12 ......... Protrusion 13 ......... Pit 15 ......... Step 100 ......... Track 101 ……… pit 103 ……… pit cover

In order to achieve the above-described object, the present invention is a pit lid, which is formed on the top plate portion and the back surface of the top plate portion, and in the width direction and the longitudinal direction of the top plate portion, A width-direction rib and a longitudinal-direction rib integrally formed so as to be orthogonal to each other, and a pair of notch-shaped handle portions, and both end portions of the width-direction rib on the side surface in the width direction of the pit lid The space defined by the longitudinal ribs opens toward the side surface in the width direction of the pit lid, thereby forming a plurality of first air flow paths in which the space communicates with the outside of the pit lid. And
The notch portion of the handle portion connects the inside of the pit lid and the outside of the pit lid directly, thereby allowing the air on the back side of the top plate portion to communicate with the outside of the pit lid . Ri Do the air flow path,
The notch portion of the handle portion is formed at both end portions in the width direction of the top plate portion, and both the formation direction of the second air flow path and the formation direction of the first air flow path are the pits. The width direction of the lid, formed in the same direction,
The width direction ribs and the longitudinal direction ribs are integrally formed perpendicularly to each other in a lattice shape by traversing or longitudinally cutting to the vicinity of the outer periphery of the top plate part,
Portions other than both ends of the width direction rib are formed continuously with respect to both ends of the width direction rib constituting the first air flow path, and further, portions other than both ends of the width direction rib A rib structure having a longitudinal rib as a wall portion and partitioned into a space in which a surface facing the top plate portion is open so that five directions are surrounded by the back surface of the top plate portion and the wall portion. A plurality of continuous vertical and horizontal are formed on the back surface of the plate part,
The rib structure formed by both end portions of the width direction rib and the longitudinal direction rib intersecting therewith has two functions of strength improvement and air flow path formation, and a portion other than both end portions of the width direction rib and the length direction. The rib structure formed by the direction ribs has an effect of improving the strength, and the width direction ribs extending to the end portions in the width direction of the pit cover are the side surfaces of the pit cover excluding the end portions of the direction ribs. Are all open and form the first air flow path and the second air flow path .

Wherein at least a portion of the width direction of the side surface of the pit lid, at least a portion of the end portion in the width direction rib, in a state where than the width direction edges of the top plate portion projecting on both sides, the width direction rib Is formed at the end of the width direction rib, and the end of the flow path holding means is brought into contact with a substantially vertical wall portion when the width direction of the top plate portion is It is desirable that a gap be maintained between the edge portion and the wall portion so that the first air flow path can be prevented from being blocked.

The width of the rib in the width direction decreases from the vicinity of the center in the width direction of the top plate portion toward both sides in the width direction, and when the space is cut in the longitudinal direction in the first air flow path. It is desirable that the cross-sectional area of the air flow path formed by the top plate portion and the width direction rib in the cross section increases toward both sides in the width direction of the top plate portion.

Concavities and convexities may be formed on the surface side of the top plate portion for the purpose of preventing slipping.

Claims (10)

A pit lid,
A width plate rib and a length direction rib formed integrally on the top plate portion and the back surface of the top plate portion so as to be orthogonal to each other in the width direction and the length direction of the top plate portion; A pair of notch-shaped handles,
At both ends in the width direction of the pit lid, a space defined by both ends of the width direction rib and the longitudinal rib opens toward the end in the width direction of the pit lid, so that the space and the pit A plurality of first air flow paths communicating with the outside of the lid are formed,
The notch part of the said handle part becomes a 2nd air flow path which directly connects the back side of the said top-plate part, and the outer side of a pit cover, The pit cover characterized by the above-mentioned. The width direction ribs and the longitudinal direction ribs are integrally formed perpendicularly to each other in a lattice shape by traversing or longitudinally cutting to the vicinity of the outer periphery of the top plate part,
Portions other than both ends of the width direction rib are formed continuously with respect to both ends of the width direction rib constituting the first air flow path, and the portion other than both ends of the width direction rib and the longitudinal direction The top plate portion has a structure in which a direction rib is used as a wall portion, and a surface facing the top plate portion is partitioned into a space opened so that five directions are surrounded by the back surface of the top plate portion and the wall portion. The pit cover according to claim 1, wherein a plurality of the pit covers are formed continuously on the back surface of the slab vertically and horizontally.   The notch portion of the handle portion is formed at both end portions in the width direction of the top plate portion, and both the formation direction of the second air flow path and the formation direction of the first air flow path are the pits. The pit cover according to claim 1, wherein the pit cover is formed in the same direction as a width direction of the cover.   The handle rib is formed on the back surface of the top plate so that the width-direction rib and the handle rib are integrally joined around the notch. The pit cover according to claim 3.   At least a part of the end surface in the width direction of the pit lid is formed with a channel holding means projecting on both sides of the width direction edge of the top plate portion, and the end of the channel holding means is substantially vertical. When contacting the wall, a gap is maintained between the edge in the width direction of the top plate and the wall, and the first air flow path can be prevented from being blocked. The pit cover according to any one of claims 1 to 4.   In the first air flow path, a cross-sectional area formed by cutting the space in the longitudinal direction and formed by the top plate portion and the width direction ribs is on both sides in the width direction of the top plate portion. The pit cover according to any one of claims 1 to 5, wherein the pit cover becomes larger as it goes to.   The top plate portion has a convex shape at the center, the thickness of the top plate portion in the first air flow path becomes thinner toward the width direction end of the top plate portion, and the width direction rib The pit cover according to any one of claims 1 to 6, wherein a height of the longitudinal rib increases toward a center of the top plate portion.   The pit cover according to any one of claims 1 to 7, wherein a width of the width direction rib decreases from the vicinity of the center in the width direction of the top plate portion toward both sides in the width direction. .   The flow path holding means has a tapered shape formed at an end portion of the width direction rib, and the end portion of the width direction rib has a tapered shape that spreads downward from a connection portion with the top plate portion. The pit cover according to claim 5, wherein:   A plurality of protrusions are formed outside the side surface on at least one side in the longitudinal rib forming direction, and when the pit cover is installed, a gap is formed by the protrusion between the side surfaces of the adjacent pit cover. The pit cover according to any one of claims 1 to 9, wherein a third air flow path that communicates the back side of the top plate portion and the outside of the pit cover can be formed.

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