JP2014005665A - Lid structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lid structure in which a lid can be tightly fitted so as to be bitten into the opening of a receiving frame, and even after a strong press-down force acts, the lid can be easily opened by an operator.SOLUTION: In a lid structure 1 embedded for an underground structure for use including: a receiving frame 2 having a circular opening 2b at a surface position P0; and a lid 3 configured to be fitted so as to be bitten into the opening of the receiving frame, the diameters of an inner peripheral surface 2 of the opening and a side section 3d of the lid become smaller by a large ratio according as they go downward, and an inner peripheral surface 2d has a lid stopper section 2e, and the lid includes a bottom edge 3b configured to be butted to the lid stopper section 2e so as not to descend toward a lower side. Height h1 from a lower limit position to a home position is set to a value such that when the bottom edge is butted to the lid stopper section, the lid can be opened with a prearranged power. In this lid structure, the lid can be tightly fitted so as to be bitten into the opening of the receiving frame, and even after a strong press-down force acts, the lid can be easily opened with a prearranged power by an operator.

Description

  The present invention relates to an improvement in a lid structure used for an underground structure, particularly a manhole cover.

  A lid having an opening connected to a passage extending from an underground structure such as a groundwater channel, an underground passage, and a sewer pipe to the surface of the earth, and a receiving frame embedded in the basement, and a lid fitted to the receiving frame As a structure, a manhole receiving frame and its lid are known. Among the lid structures, those that do not have a locking mechanism and that cover with their own weight, so that the lid does not easily come off from the receiving frame due to wind blown from the basement or vibration applied to the lid, etc. Generally, iron is used. Further, a lid structure of a type in which a side surface of the opening of the lid and the receiving frame is inclined so that the lid bites into the opening of the receiving frame is known (see Patent Document 1).

Patent No. 3886037

  When a lid structure of a type that fits so that the lid bites into the opening of the receiving frame is provided on the roadway or the like, the lid receives a strong pressing force every time a heavy freight vehicle or the like passes over. This strong pressing force also exerts a force in the direction of radially expanding the opening of the receiving frame. Further, when the lid is strongly pressed down, the lid warps and the diameter slightly shrinks. As a result, the lid is lowered to a position below the planned position every time it receives a strong pressing force. The lid tightly fitted in this way cannot be easily opened by the operator's force or an open / close device such as an open / close handle, and the work of cutting the cover using a burner or the work of digging the receiving frame from the ground is not possible. It is a problem that becomes necessary.

  The present invention has been made in order to solve the above-described problem. At the same time, the lid can be firmly fitted so as to bite into the opening of the receiving frame, and at the same time, even after a strong pressing force acts, That is, an object of the present invention is to provide a lid structure that can be easily opened using the force of an operator or an opening / closing device such as an opening / closing handle.

  In order to achieve the above object, the present invention is embedded and used for underground structures, a receiving frame having a circular opening at the ground surface position, and a circular lid fitted so as to bite into the opening of the receiving frame, In the lid structure provided with the opening, the opening has an inner peripheral surface whose diameter decreases at a large rate as it goes downward from the ground surface position to the lower limit position, and a position having a diameter smaller than that of the lid at the lower limit position. And a lid stopper that protrudes in the center direction from the inner peripheral surface, and the lid is shaped along the inner peripheral surface of the opening and is fitted to the opening with a predetermined force. The side surface having a diameter for stopping the lid at a fixed position above the lower limit position of the inner peripheral surface, and the lid stopper portion so that the lid does not drop when fitted with a force stronger than the force. A bottom edge, and one of the lid and the opening Both are elastically deformed so that when the lid is fitted with the strong force, the lid is fitted to a position below the fixed position, and the height from the lower limit position to the fixed position is the bottom edge. Is set to a value that allows the lid to be opened with a predetermined force when it is in contact with the lid stopper.

  The radial thickness of the receiving frame is preferably increased as it goes downward to the lower limit position.

  According to the present invention, the lid fits tightly so as to bite into the opening of the receiving frame at the top of the steep slope. By adjusting the amount of the steep upper portion, a desired amount of the portion can be firmly fitted into the opening of the receiving frame regardless of the thickness of the lid. At the same time, the lid can be easily opened with a predetermined force because the lid does not drop below the lower limit position even when a strong pressing force is applied. As described above, the lid structure of the present invention can easily fit the lid with the opening of the receiving frame while always using a predetermined force even when used in an environment where a strong pressing force acts. Can be opened.

(A) is a perspective view of the lid structure according to the first embodiment of the present invention, (b) is a perspective view showing a state in which the lid structure is embedded in the ground. (A) is sectional drawing of the same lid structure, (b) is the elements on larger scale of sectional drawing, (c) is a top view of a receiving frame. The vector diagram which shows the force which acts on the receiving frame of a lid | cover.

  A lid structure according to an embodiment of the present invention includes a receiving frame having an opening and a lid fitted into the opening. The contact surface between the opening of the receiving frame and the lid is inclined so that the lid fits into the opening. The opening of the receiving frame has a lid stopper for stopping the lid from being lowered below the lower limit position lower than a fixed position where the lid stops when the lid is closed by its own weight or a predetermined force. The distance between the fixed position and the lower limit position is set to a value that can open the lid with a predetermined force when the bottom edge is in contact with the lid stopper. By adopting the above configuration, even if a strong force is applied to push the lid further downward from the fixed position, the lid does not fall below the lower limit position and can be opened with a predetermined force.

  FIG. 1A shows the lid structure 1 according to the first embodiment, and FIG. 1B shows the lid structure 1 in a state of being buried in the ground. The lid structure 1 is embedded and used for an underground structure, and includes a receiving frame 2 having a circular opening at the surface position, and a circular lid 3 fitted so as to bite into the opening of the receiving frame 2. Yes. The receiving frame 2 is connected to an underground structure such as an underground waterway, an underground passage, or a sewer.

  As shown in FIG.1 (b), the main-body part 2c of the receiving frame 2 is embedded and used in the ground. Only the edge 2a of the receiving frame 2 and the lid 3 appear on the ground surface.

  FIG. 2A shows a cross section of the receiving frame 2 and the lid 3. FIG. 2B shows an enlarged view of a portion where the inner peripheral surface 2 d of the opening 2 b of the receiving frame 2 is in contact with the side surface 3 a of the lid 3. FIG. 2C shows the receiving frame 2 as viewed from above.

  The diameter of the inner peripheral surface 2d of the receiving frame 2 decreases at a larger rate from the ground surface position P0 toward the lower limit position P1. The radial thickness D of the inner peripheral surface 2d of the receiving frame 2 increases as it goes from the ground surface position P0 to the lower limit position P1. The receiving frame 2 has a lid stopper 2e that protrudes from the inner circumferential surface 2d in the center direction at a lower limit position P1 of the inner circumferential surface 2d until it has a smaller diameter than the lid. As shown in FIG. 2 (c), the cover frame 2e has a ring or ring shape when viewed from above. Further, the lid stopper 2e secures the function of stopping the lid 3 so as not to be lowered below the lower limit position P1, while providing the deletion portion 2f intermittently along the circumference, thereby reducing the weight of the receiving frame 2. I am trying.

  The side surface 3 a of the lid 3 has a shape along the inner peripheral surface 2 d of the receiving frame 2. The lid 3 includes a bottom edge 3b that abuts against the lid stopper 2e so that the lid 3 does not drop when fitted with a force stronger than a predetermined force. The lid 3 has a diameter at which the bottom edge 3b stops at a fixed position P2 above the lower limit position P1 of the inner peripheral surface 2d of the receiving frame 2 when the lid 3 is fitted into the opening 2b of the receiving frame 2 using a predetermined force or its own weight. Have The height h1 (mm) from the lower limit position P1 to the fixed position P2 is a value larger than 0, and the lid 3 is determined in advance when the lid 3 is pushed down to a position where the bottom edge 3b contacts the lid stopper 2e. It is set to a value that can be opened with a strong force.

  The side surface 3a of the lid 3 is designed to have the same shape as the circular arc of a circle having a radius R, for example, 145 mm, whose center is located at a position h2 above the upper surface of the lid 3, for example, 2 mm, in the cross-sectional shape. . The inclination angle (hereinafter the same) α1 representing the acute angle of the intersection of the tangent line and the horizontal line at the substantially intermediate position between the ground surface position P0 and the lower limit position P1 of the inner peripheral surface 2d of the receiving frame 2 and the side surface 3a of the lid 3 The angle that fits in, for example, 50 degrees or more and less than 90 degrees, preferably 70 degrees or more and less than 90 degrees, is set to a specific angle, for example, 81 degrees. The inclination angle α2 of the bottom edge 3b in the vicinity of the lower limit position P1 is set to a specific angle within the range of 45 degrees or more and less than α1, for example 60 degrees. By adopting the above configuration, the lid 3 is fitted and fixed so as to bite into the inner peripheral surface 2d of the receiving frame 2 on the side surface 3a of the lid 3 in the vicinity of the inclination angle α1.

  The value of the height h1 is set based on experimental data on the relationship between the force required to open the lid 3 and the biting position. When the bottom edge 3b is in contact with the lid stopper 2e, it is necessary to lift the lid 3 using a force that is greater than the force required for ordinary work of a general worker. It is set to a value that can lift the lid 3 reliably (hereinafter referred to as a set value of the height h1) without damaging an opening / closing device such as a bar or an opening / closing handle used by the operator. For example, when a bar is inserted into the edge of the lid 3 and the lid 3 is opened by the lever principle, the value is set so that the lid 3 can be lifted reliably without breaking the bar. In a certain example, the set value of the height h1 was 1.5 mm.

  In the above example, the height h1 is most preferably a set value of 1.5 mm, but an upper limit value greater than 1.5 mm can be determined in consideration of manufacturing errors. If this upper limit value exceeds this value, it is a value at which a general worker cannot lift the lid 3 with his or her own force or with an opening / closing device such as a bar or an opening / closing handle. It is a value that requires a force greater than the force that can be exhibited by the operator, or a value that can be opened only by a force that may break the opening / closing device (hereinafter referred to as an upper limit value of the height h1). In the example in which the lid 3 was pry open using the bar, the upper limit value of the height h1 at which the lid 3 could be reliably opened without breaking the bar was 2 mm.

  In addition, as long as the set value of the height h1 and the upper limit value thereof satisfy the above-described requirements, for each lid structure 1, the power that can be assumed by the operator, whether or not the switchgear is used, and when it is used Is set to a preferable value in consideration of the strength of the switchgear, the diameter, shape, material, ease of deformation, and the like of the receiving frame 2 and the lid 3.

FIG. 3 shows the forces F ₁ 1, F ₂ 1, F ₃ 1 (kgf) that the lid 3 gives to the receiving frame 2 along the direction of gravity when the inclination angles α3, α4, α5 are 80 degrees, 45 degrees, and 10 degrees. ) (Hereinafter simply referred to as F1). Further, FIG. 3, the force _F 1 _{2, F 2} 2 giving a direction towards the outer periphery from the center of the lid 3, F 3 2 and (kgf), the force _F 1 3 acting in a direction to expand the diameter of the receiving frame 2, F ₂ 3 and F ₃ 3 (kgf) (hereinafter simply referred to as F3) are displayed as vectors. From this figure, it can be seen that the strongest force F3 acts in the direction of expanding the diameter of the receiving frame 2 when the inclination angle is 45 degrees. In the lid structure 1, an arc region surrounded by a dotted line 30 is used for the shape of the side surface 3 a of the lid 3.

  When a force F1 that pushes down the lid 3 in the direction of gravity (downward in the drawing) is applied to the side surface 3a of the lid 3, the force F3 in the outer circumferential direction indicated by the arrow A1 is simultaneously applied to the inner circumferential surface 2d of the receiving frame 2 by the force dispersion action. Add. In this case, the iron receiving frame 2 is elastically deformed so that the diameter of the opening 2b increases. Further, when a force is applied to the vicinity of the center of the lid 3, the center of the lid 3 is deformed so as to be recessed from the periphery, and the upper radius of the side surface 3 a of the lid 3 is reduced. As a result, the side surface 3 a of the lid 3 has a steep slope and bites into the opening 2 b of the receiving frame 2. However, the lid 3 does not fall below the lower limit position P1 due to the action of the lid stopper 2e even when a strong pressing force is applied. For this reason, the operator can easily open the lid 3 even after a strong pressing force is applied.

  The thickness of the lid 3 has a design lower limit value to ensure strength and weight. If the diameters of the side surface 3a of the lid 3 and the inner peripheral surface 2d of the receiving frame 2 decrease only in a straight line, all the side surfaces 3a of the lid 3 are fitted so as to bite into the inner peripheral surface 2d of the receiving frame 2. In this case, there is a large increase in the force required to lift the lid 3 which increases by fitting below the fixed position, and as a result, the set value of the height h1 and its upper limit value are small. When the set value of the height h1 and the upper limit value thereof are small values, the allowable manufacturing error is small and manufacturing is difficult. On the other hand, the diameter of the side surface 3a of the lid 3 is designed to decrease at a larger rate toward the lower limit position P1, and the opening of the receiving frame 2 is secured while ensuring the necessary thickness of the lid 3. The portion that fits into 2b is adjusted to a desired amount. By adopting this configuration, a desired amount of the portion can be firmly fitted into the opening of the receiving frame regardless of the thickness of the lid. As a result, the set value of the height h1 and the upper limit value thereof can be set to a relatively large value, and accordingly, a manufacturing tolerance represented by the difference between the set value of the height h1 and the upper limit value thereof is also obtained. Since it can be enlarged, manufacture becomes easy.

  When the diameter of the side surface 3a of the lid 3 is set to the above shape, the ratio of the force acting so as to push the inner peripheral surface 2d of the receiving frame 2 in the outer peripheral direction near the lower limit position P1 increases. However, since the inner peripheral surface 2d of the receiving frame 2 resists the force that expands in the outer peripheral direction, as shown in FIG. 2B, the thickness D increases as the opening 2b of the frame receiving 2 approaches the lower limit position P1. Therefore, the amount by which the lid 3 is pushed below the fixed position P2 is small.

  As described above, the lid 3 is adjusted to have a desired amount of a portion that fits into the opening 2b of the receiving frame 2 while ensuring a necessary thickness, and is lower than the fixed position P2. Even if it receives a strong force to push in, the amount pushed in can be reduced.

  For example, in the vicinity of the ground surface position P0 of the inner peripheral surface 2d of the receiving frame 2, there is a portion corresponding to the lid stopper 2e having an inclination angle α1 of 40 to 50 degrees, and the inclination angle α2 is below 60 to less than 90 degrees below it. Consider a comparative lid structure having a portion that fits in. In this comparative lid structure, when the lid is pushed down, a force for expanding the diameter of the opening is applied to a thin portion of the inner peripheral surface 2d of the receiving frame 2 near the ground surface position P0, and the diameter of the opening is widened. With respect to this comparative lid structure, the lid structure 1 has a portion that fits in the vicinity of the ground surface position P0 of the inner peripheral surface 2d of the receiving frame 2, and a thick portion near the lower limit position below the lid structure 1. It has a lid stopper 2e. The lid structure 1 of the present embodiment suppresses the expansion of the diameter of the opening 2b compared to the comparative lid structure, even when a strong force is applied to push the lid 3 below the fixed position. The amount pushed down below the position P2 (but above the lower limit position P1) can be reduced.

  The lid structure of the present invention is not limited to the configuration shown in the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the lid 3 may include one or a plurality of air holes in order to prevent the lid 3 from being lifted by wind blown from the underground structure.

  The lid structure of the present invention is not only for underground waterways, underground passages and sewerage channels, but also for connecting underground structures such as underground pipes in which, for example, optical fiber cables and telephone lines are buried, to the ground surface, in particular, roadways. It can be used effectively.

DESCRIPTION OF SYMBOLS 1 Lid structure 2 Receiving frame 2b Opening 2d Inner peripheral surface 2e Lid stop part 3 Lid 3a Side surface 3b Bottom edge P0 Ground surface position P1 Lower limit position P2 Fixed position h1 Height from lower limit position to fixed position

Claims (2)

In a lid structure comprising a receiving frame having a circular opening at a ground surface position, and a circular lid fitted so as to bite into the opening of the receiving frame, embedded and used for an underground structure,
The opening has an inner peripheral surface that decreases in diameter as it goes downward from the ground surface position to the lower limit position, and a central direction from the inner peripheral surface to a position that has a smaller diameter than the lid at the lower limit position. And a lid stopper protruding to
The lid has a shape along the inner peripheral surface of the opening, and a side surface having a diameter for stopping the lid at a fixed position above the lower limit position of the inner peripheral surface when fitted to the opening with a predetermined force; A bottom edge that contacts the lid stopper and prevents the lid from being lowered when fitted with a force stronger than the force,
One or both of the lid and the opening are elastically deformed so that when the lid is fitted with the strong force, the lid is fitted to a position below the fixed position,
The height from the lower limit position to the fixed position is set to a value that can open the lid with a predetermined force when the bottom edge is in contact with the lid stopper. Lid structure. The lid structure according to claim 1, wherein a thickness of the receiving frame in a radial direction increases toward a lower limit position.

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