Lid for underground structure

Abstract

To prevent a receiving frame from coming off an underground structure when internal pressure increases.SOLUTION: A lid for an underground structure includes a receiving frame 2 that is fixed to the upper end of the underground structure, a lid body 3 which closes the upper opening of the receiving frame 2 in an openable and closable manner, a first connecting member (41) which connects the lid body 3 to the receiving frame 2 so that the lid body 3 does not come off the receiving frame 2 when internal pressure that pushes lid body 3 upward increases, and second connecting members (51, 52) which connect the lid body 3 to the receiving frame 2 at a position away from the first connecting member (41). The first connecting member (41) includes a body part 48, a supported part 45 that is supported by the lower surface part of the lid body 3, and a connecting part 46 that connects the body part 48 and the supported part 45, the supported part 45 includes a shaft part 451 that is connected to the lower surface part of the lid body 3 and has a first axial direction A1, and the connecting part 46 includes an outer circumferential surface 461 and a groove (47) that is formed on the outer circumferential surface 461 so that the breaking strength of the first connecting member (41) is smaller than the breaking strength of the second connecting members (51, 52).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lid for an underground structure comprising a receiving frame fixed to the upper end of an underground structure and a lid body that closes the upper opening of the receiving frame in an openable and closable manner. [Background technology]

[0002] One example of the above-mentioned underground structure lid is disclosed in the following Patent Document 1. The underground structure lid of Patent Document 1 includes a receiving frame fixed to the upper end of the underground structure, a lid body that closes the upper opening of the receiving frame in an openable and closable manner, and a lock that locks the lid body so that it cannot be opened illegally. The lock includes a pin that is pivotally attached to a pivot part formed on the lower surface of the lid body, and an engagement protrusion that engages with a lock seat formed on the inner periphery of the receiving frame. The engagement protrusion engages with the lock seat when the lid body is slightly moved upward, thereby preventing the lid body from being opened (opened). This prevents outsiders from opening the lid body and illegally dumping foreign objects. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 62-159560 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned underground structure lid, when the internal pressure of the underground structure rises due to, for example, the inflow of rainwater, the increased internal pressure causes the lid body to rise from the receiving frame, releasing the internal pressure. That is, a gap is formed between the engagement protrusion of the lock and the lock seat of the receiving frame to allow the lid body to rise, and when the internal pressure rises, the lid body can rise from the receiving frame by a maximum amount equal to this gap. When the lid body rises, a gap is formed between the receiving frame and the lid body, and the internal pressure is released through this gap.

[0005] However, for example, if a large amount of rainwater flows in due to a torrential downpour and the internal pressure rises suddenly, the internal pressure may not be released even if the lid body rises to its limit. If this situation occurs, further internal pressure is applied to the lid body with the lock engaged with the lock seat, and a force is applied from the lid body via the lock that strongly pulls the frame upward. If the lock is too strong at this time, a large force that exceeds the guaranteed strength of the bolts that secure the frame to the underground structure may act on the frame, causing it to detach from the underground structure together with the lid body.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a cover for an underground structure that can prevent the receiving frame from detaching from the underground structure when internal pressure increases. [Means for solving the problem]

[0007] In order to solve the above problem, a lid for an underground structure according to one aspect of the present invention comprises a receiving frame fixed to the upper end of an underground structure, a lid body that closes the upper opening of the receiving frame in an openable and closable manner, a first connecting member that connects the lid body to the receiving frame so that the lid body does not detach from the receiving frame when the internal pressure increases and the lid body is pressed upward, and a second connecting member that connects the lid body to the receiving frame at a position away from the first connecting member, wherein the first connecting member includes a main body portion, a supported portion supported on the underside of the main body portion, and a connecting portion that connects the main body portion and the supported portion, wherein the supported portion includes an axial portion connected to the underside of the lid body and has a first axial direction, and the connecting portion includes an outer circumferential surface and a groove formed on the outer circumferential surface so that the breaking strength of the first connecting member is smaller than the breaking strength of the second connecting member.

[0008] According to the present invention, when the internal pressure rises and the lid body is pressed upward, the lid body is connected to the receiving frame by the connecting members (first and second connecting members), so that the lid body can be prevented from coming off the receiving frame. However, if the connection by such connecting members is unlimited, for example, when the internal pressure rises suddenly due to the inflow of a large amount of rainwater caused by a torrential rain, the lid body strongly pulls the receiving frame upward via the connecting members, and as a result, the fixing between the receiving frame and the underground structure is released, and the receiving frame may come off from the underground structure. In contrast, in the present invention, a groove is formed on the outer peripheral surface of the connection part of the first connecting member, so that the groove can reduce the breaking strength of the first connecting member to be lower than the breaking strength of the second connecting member. Therefore, the first connecting member can be broken before the second connecting member before the receiving frame comes off from the underground structure, and the internal pressure can be released. In this way, the internal pressure can be released while maintaining the connection between the lid body and the receiving frame via the second connecting member, so that the lid body can be prevented from coming off from the receiving frame even if the internal pressure rises suddenly.

[0009] Preferably, the recessed groove is a groove having a substantially flat bottom surface and a rectangular cross section.

[0010] In this way, when the groove has a rectangular cross-section, excessive stress concentration is less likely to occur compared to, for example, when the cross-section is V-shaped, so the effect of lowering the breaking strength of the first connecting member below the breaking strength of the second connecting member can be consistently obtained, making it easier to keep the breaking strength of the first connecting member close to the target value.

[0011] Preferably, the recessed groove includes a groove formed along a plane parallel to the first axial direction.

[0012] In this embodiment, the groove is formed along a plane parallel to the first axial direction, so that the direction in which the lid body is pressed upward intersects with the direction in which the groove is formed, and therefore, when the internal pressure suddenly increases, stress concentration occurs in the groove, making it easier for the first connecting member to break before the second connecting member breaks.

[0013] Preferably, the shaft portion includes a first shaft portion and a second shaft portion opposing each other in the first axial direction, the connection portion includes a first wall portion connecting the main body portion and the first shaft portion and a second wall portion connecting the main body portion and the second shaft portion, and the groove includes a first groove formed in the first wall portion and a second groove formed in the second wall portion.

[0014] In this embodiment, the connection portion includes a first wall portion connecting the main body portion and the first shaft portion, and a second wall portion connecting the main body portion and the second shaft portion, and a first groove is formed in the first wall portion and a second groove is formed in the second wall portion, so that at least one of the first wall portion and the second wall portion can be broken in the event of a sudden rise in internal pressure.

[0015] Preferably, the lid for underground structures further includes a blocking member that blocks a tool insertion hole formed in the lid body from the underside of the lid body to allow the insertion of an opening and closing tool, the blocking member being supported by the first connecting member so as to be slidable in the vertical direction between the first wall portion and the second wall portion, the first groove being a groove formed in a portion of the first wall portion that does not face the second wall portion, and the second groove being a groove formed in a portion of the second wall portion that does not face the first wall portion.

[0016] In this embodiment, the tool insertion hole formed in the lid body for inserting an opening / closing tool is blocked by the blocking member that can slide in the vertical direction, so that it is possible to suppress the inflow of rainwater, etc. from the tool insertion hole into the underground structure. Also, the blocking member is pushed downward only when necessary to open the tool insertion hole, and in that state, the lid body can be opened and closed. Furthermore, since the blocking member is disposed between the first wall portion and the second wall portion, and no groove is formed in the mutually opposing portions of the first wall portion and the second wall portion (i.e., the groove is formed in the mutually non-opposing portions), it is possible to prevent the blocking member from getting caught in the groove when sliding in the vertical direction, and the blocking member can be smoothly slid in the vertical direction.

[0017] Preferably, the blocking member includes a head blocking the tool insertion hole from the underside of the lid body, a body extending from the head in a second axial direction, and a pin protruding in a direction intersecting the second axial direction, and the main body of the first connecting member includes a body insertion hole allowing the body to slide in an up-down direction, a pin insertion hole allowing the pin to slide in an up-down direction, and a space portion in which the pin is movable as the body rotates about the second axial direction, and the space portion has an upward regulating portion that regulates upward movement of the pin.

[0018] In this embodiment, the blocking member can be easily assembled to the first connecting member. That is, the blocking member has a body and a pin, and a body insertion hole and a pin insertion hole through which the body and the pin can slide in the up and down direction are formed in the main body of the first connecting member. Therefore, when assembling the blocking member to the first connecting member, the body and the pin are inserted into the body insertion hole and the pin insertion hole, respectively, and the blocking member is pressed down until the pin reaches the space, and then the blocking member is rotated around the second axial direction of the body so that the pin is positioned below the upper regulating part of the space. This makes it possible to restrict the upward movement of the pin so that it does not come out of the main body of the first connecting member. In this way, the blocking member can be assembled to the first connecting member by inserting the body and the pin into the body insertion hole and the pin insertion hole, and then rotating the blocking member around the second axial direction of the body, thereby facilitating the assembly work of the blocking member. Effect of the Invention

[0019] As described above, the underground structure cover of the present invention can prevent the receiving frame from detaching from the underground structure when the internal pressure increases. [Brief description of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of a cover for an underground structure according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a top view of the above-mentioned underground structure cover. [Diagram 3]1 is an exploded perspective view of the lock mechanism (excluding the lock seat) in a disassembled state, seen obliquely from above. [Figure 4] FIG. 2 is a perspective view of the assembled lock mechanism (excluding the lock seat) as viewed obliquely from above. [Diagram 5] FIG. 2 is a bottom view of the lock mechanism (excluding the lock seat). [Figure 6] FIG. 2 is a cross-sectional view of the lock mechanism (excluding the lock seat). [Figure 7] 4 is a perspective view of the lock member of the lock mechanism as viewed obliquely from above. FIG. [Figure 8] 1A to 1C are three views of the lock member as viewed from three directions, where (a) is a top view, (b) is a front view, and (c) is a bottom view. [Figure 9] 9 is a diagram showing a part of the end surface taken along line IX-IX in FIG. 8(b). [Figure 10] 11 is a perspective view showing a state in which a blocking member is assembled to the lock member. FIG. [Figure 11] 5A and 5B are diagrams for explaining the movement of the body and pin of the closing member during assembly, in which (a) shows the initial state of assembly and (b) shows the later state of assembly. [Figure 12] 2 is a cross-sectional view showing the hinge mechanism in a section different from that of FIG. 1; [Figure 13] FIG. 2 is a perspective view of the hinge mechanism (excluding hinge seat 27 and claw seat 28) as viewed obliquely from below. [Figure 14] 11 is a cross-sectional view showing a state in which an opening / closing tool is inserted into a tool insertion hole of the lid body. FIG. [Figure 15] 11 is a cross-sectional view showing the state in which the lock member is tilted by an inserted opening / closing tool. FIG. [Figure 16] 4 is a cross-sectional view showing the state in which the lid body is pulled out above ground. FIG. [Figure 17] 1 and shows a state in which the lid body is lifted up due to internal pressure. FIG. [Figure 18] 4 is a cross-sectional view showing a state in which the lid body is opened due to the breakage of the lock member. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] [Overall configuration of underground structure cover] Hereinafter, an embodiment of the underground structure cover of the present invention will be described with reference to the drawings. In this specification, the underground structure cover is a general term for a cover that closes an opening of an underground structure in an openable and closable manner, and includes the following examples. --Large iron covers, manhole covers, manhole covers, and trench covers that close openings in sewer systems that connect underground buried objects, underground structural facilities, etc. to the ground. -- Iron covers for utility tunnels, iron covers for power transmission, and iron covers for power distribution to protect underground facility equipment and underground cables for power transmission or communication. --Fire hydrant covers, water control valve covers, gate valve covers, air valve covers, gas pipe covers, and water meter covers that function as opening and closing doors connecting buried conduits and their associated equipment below the road surface in water supply and gas piping to the ground.

[0022] 1 and 2 are a cross-sectional view and a top view of an underground structure cover 1 according to an embodiment of the present invention. As shown in the figure, the underground structure cover 1 includes a receiving frame 2, a cover body 3, a locking mechanism 4, and a hinge mechanism 5. The receiving frame 2 is a frame body that is circular in top view and fixed to the upper end of an underground structure (not shown). The underground structure is, for example, a cylindrical structure extending in the vertical direction that functions as a manhole through which workers can enter and exit. The cover body 3 is a member that is circular in top view and closes the upper opening 21 of the receiving frame 2 in an openable and closable manner. The locking mechanism 4 is a mechanism that prevents the cover body 3 from being opened illegally. The hinge mechanism 5 is a mechanism that hinges the cover body 3 to the receiving frame 2 so as to function as a fulcrum for the cover body 3 when the cover is opened. The locking mechanism 4 and the hinge mechanism 5 are arranged approximately 180° apart in the circumferential direction so as to face each other across the center of the cover body 3. The underground structure cover 1 is installed so that the upper surface of the cover body 3 is flush with the ground surface.

[0023] 1 and 2, the receiving frame 2 includes a flange 22 that is fastened to an underground structure via bolts (not shown), and a peripheral wall 23 that extends upward from the flange 22. A plurality of bolt holes 24 through which the bolts are inserted are formed in the flange 22. A lid support portion 25 that supports the lid main body 3 is formed at the upper end portion of the peripheral wall 23.

[0024] The lid body 3 has a tool insertion hole 31 formed at a position where the lock mechanism 4 is disposed. The tool insertion hole 31 is a hole for inserting an opening / closing tool 100 used in an unlocking operation for releasing the connection between the lid body 3 and the receiving frame 2 by the lock mechanism 4. The lid body 3 has a cylindrical hole seat 32 extending downward from the periphery of the tool insertion hole 31.

[0025] [Lock mechanism details] FIG. 3 is an exploded perspective view of the disassembled lock mechanism 4 (excluding the lock seat 26) seen from diagonally above. Also, FIGS. 4 to 6 are a perspective view, a bottom view, and a cross-sectional view showing the lock mechanism 4 (excluding the lock seat 26) in an assembled state. As shown in FIG. 1 and FIGS. 3 to 6, the lock mechanism 4 includes a lock member 41, a blocking member 42, a spring 43, and the lock seat 26 (FIG. 1). The lock member 41 is a member that connects the lid body 3 to the receiving frame 2 so that the lid body 3 does not come off from the receiving frame 2 when the internal pressure increases by pressing the lid body 3 upward, and is supported on the lower surface of the lid body 3. The blocking member 42 is a member that blocks the tool insertion hole 31 of the lid body 3 from the lower side, and is assembled to the lock member 41 in a state in which it can slide up and down. The spring 43 is a compression coil spring that urges the blocking member 42 upward relative to the lock member 41. The lock seat 26 is a protrusion formed integrally with the inner periphery of the receiving frame 2, and has a shape that allows it to engage with an engaging portion 481 (described later) of the lock member 41 when the internal pressure increases.

[0026] The lock member 41 integrally includes a main body portion 48 , a supported portion 45 supported on the underside of the lid main body 3 , and a connecting portion 46 connecting the main body portion 48 and the supported portion 45 .

[0027] The supported portion 45 has a shaft portion 451 connected to the lower surface of the lid main body 3, and has a first axial direction A1. Specifically, the supported portion 45 has a first shaft portion 451a and a second shaft portion 451b that face each other in the first axial direction A1. In this example, the first shaft portion 451a and the second shaft portion 451b are protruding shaft portions. The first shaft portion 451a and the second shaft portion 451b are connected to concave bearing portions (not shown) provided at two locations on the lower surface of the lid main body 3. Note that the concave shaft portion and the protruding bearing portion may be used. The bearing portions are provided at two locations facing each other across the tool insertion hole 31 in the lid main body 3, and the first shaft portion 451a and the second shaft portion 451b are respectively connected to the two bearing portions. As a result, the lock member 41 is attached to the underside of the lid main body 3 in a state in which it can swing in the radial direction of the lid main body 3.

[0028] The connection portion 46 has a first wall portion 46a that connects the main body portion 48 and the first shaft portion 451a, and a second wall portion 46b that connects the main body portion 48 and the second shaft portion 451b.

[0029] The main body 48 integrally has an engagement portion 481 that can engage with the lock seat 26 of the receiving frame 2, and a base 482 to which the engagement portion 481 is connected. The base 482 is formed in a block shape as a base that supports the first wall portion 46a and the second wall portion 46b.

[0030] The engaging portion 481 is a protrusion formed integrally with the surface of the base 482 facing the peripheral wall 23 of the receiving frame 2. The engaging portion 481 protrudes from the base 482 radially outward and upward of the lid body 3 so as to face the lock receiving seat 26 in the up-down direction. The engaging portion 481 is disposed so as to leave a predetermined vertical gap between the lock receiving seat 26 and the engaging portion 481 when the lid body 3 is closed to close the upper opening 21 of the receiving frame 2 (fitted into the lid support portion 25), as shown in FIG. 1. This gap corresponds to the floating allowance Fs (FIG. 17) of the lid body 3 described later.

[0031] The engagement portion 481 positioned as described above engages with the lock seat 26 of the receiving frame 2 when the internal pressure of the underground structure rises (details will be described later) causing the lid body 3 to rise (be pressed upward). This engagement prevents the lid body 3 from rising any further relative to the receiving frame 2. That is, the locking member 41 including the engagement portion 481 can limit the amount of rise of the lid body 3 due to an increase in internal pressure to a predetermined amount (floating distance Fs) or less. In other words, the locking member 41 has the function of restraining the lid body 3 from coming off the receiving frame 2 when the internal pressure rises. Such a locking member 41 corresponds to the "first connecting member" in this invention.

[0032] The blocking member 42 integrally has a head 421, a body 422 extending from the head 421 in a second axial direction B1 (Figure 6), and a pair of pins 423 (Figure 3) protruding from the lower end of the body 422 in a direction intersecting the second axial direction B1.

[0033] The head 421 constitutes the upper end of the blocking member 42, and has a protruding portion 421a, a seat portion 421b, and a pair of protruding pieces 421c. The protruding portion 421a is formed so as to protrude upward from the seat portion 421b. The seat portion 421b is formed in a ring shape so as to surround the periphery of the protruding portion 421a. The pair of protruding pieces 421c are formed so as to protrude from two points of the seat portion 421b toward the first wall portion 46a and the second wall portion 46b, respectively, when the blocking member 42 is assembled to the lock member 41 (specifically, between the first wall portion 46a and the second wall portion 46b). In addition, when the lock member 41, the blocking member 42, and the spring 43 are assembled to the lid main body 3, the head 421 is disposed so that the protruding portion 421a is located directly below the tool insertion hole 31 and the seat portion 421b is in close contact with the lower surface of the hole seat 32 around the tool insertion hole 31. As a result, the tool insertion hole 31 is closed by the head 421 .

[0034] The body portion 422 is a rod-shaped body extending in the second axial direction B1 from the protruding portion 421a of the head portion 421. The body portion 422 functions as a slide axis when the closing member 42 slides relative to the lock member 41 in the up and down direction.

[0035] FIG. 7 is a perspective view showing the lock member 41 alone. As shown in FIGS. 3, 4 and 7, the connection portion 46 of the lock member 41 includes an outer peripheral surface 461 and a groove 47 formed in the outer peripheral surface 461. Specifically, a first groove 47a is formed in the outer peripheral surface of the first wall portion 46a, and a second groove 47b is formed in the outer peripheral surface of the second wall portion 46b. The first groove 47a and the second groove 47b are formed along a plane A11 parallel to the first axial direction A1 at height positions between the main body portion 48 and the first shaft portion 451a and between the main body portion 48 and the second shaft portion 451b.

[0036] 7, the first wall portion 46a has an inner surface 46aa facing the second wall portion 46b, an outer surface 46ab opposite the inner surface 46aa, and a pair of side surfaces 46ac connecting the inner surface 46aa and the outer surface 46ab. The second wall portion 46b has an inner surface 46ba facing the first wall portion 46a, an outer surface 46bb opposite the inner surface 46ba, and a pair of side surfaces 46bc connecting the inner surface 46ba and the outer surface 46bb.

[0037] The first groove 47a is formed on the outer surface 46ab and a pair of side surfaces 46ac of the first wall portion 46a. That is, the groove 47 is formed in a portion of the first wall portion 46a that does not face the second wall portion 46b. The second groove 47b is formed on the outer surface 46bb and a pair of side surfaces 46bc of the second wall portion 46b. That is, the groove 47 is formed in a portion of the second wall portion 46b that does not face the first wall portion 46a.

[0038] In this way, the groove 47 is not formed on the inner surfaces 46aa and 46ba, which are the opposing portions of the first wall portion 46a and the second wall portion 46b (i.e., the groove is formed in the non-facing portions), so that it is possible to prevent the blocking member 42 from getting caught in the groove 47 when sliding in the vertical direction, and the blocking member 42 can be smoothly slid in the vertical direction.

[0039] Fig. 8(a)-(c) are a top view, a front view, and a bottom view showing the lock member 41 alone. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 8(b). As shown in Fig. 9, the recessed groove 47 is a groove having a substantially flat bottom surface 471 and a rectangular cross section.

[0040] The groove 47 as described above reduces the strength of the connection portion 46, in other words, the strength of the locking member 41 including the connection portion 46. When the cover body 3 is pressed upward due to an increase in the internal pressure of the underground structure, the engagement portion 481 of the locking member 41 engages with the lock receiving seat 26 of the receiving frame 2, and various forces such as tension, compression, and bending act on the locking member 41. When these forces become large, at least one of the first wall portion 46a and the second wall portion 46b breaks. In this specification, the force that breaks at least one of the first wall portion 46a and the second wall portion 46b (the connection portion 46) is defined as the breaking strength of the locking member 41. The breaking strength of the locking member 41 is reduced compared to the case without the groove 47 due to the effect of the groove 47 described above. In detail, the breaking strength of the locking member 41 is set to be smaller than the breaking strength of the engagement claw 52 of the hinge mechanism 5 described later.

[0041] As shown in FIG. 3, FIG. 4, FIG. 7, FIG. 8, etc., a pair of protrusions 462a is formed on the inner surface 46aa of the first wall portion 46a, and a pair of protrusions 462b is formed on the inner surface 46ba of the second wall portion 46b. The pair of protrusions 462a formed on the inner surface 46aa of the first wall portion 46a are formed to protrude from the inner surface 46aa toward the opposing second wall portion 46b and to extend in the vertical direction along both side edges of the inner surface 46aa. The pair of protrusions 462a are arranged at an interval in a direction perpendicular to both the first axial direction A1 and the vertical direction (in other words, in the radial direction of the lid body 3). The pair of protrusions 462b formed on the inner surface 46ba of the second wall portion 46b are formed to protrude from the inner surface 46ba toward the opposing first wall portion 46a and to extend in the vertical direction along both side edges of the inner surface 46ba. The pair of protrusions 462b are disposed with a gap therebetween in a direction perpendicular to both the first axial direction A1 and the up-down direction (in other words, the radial direction of the lid main body 3).

[0042] Between the pair of protrusions 462a, one of the pair of protrusions 421c formed on the head 421 of the blocking member 42 can be inserted. Also, between the pair of protrusions 462b, the other of the pair of protrusions 421c formed on the head 421 of the blocking member 42 can be inserted. That is, the blocking member 42 is assembled to the lock member 41 at an angular position where the pair of protrusions 421c are inserted between the corresponding pair of protrusions 462a, 462b (see Figs. 3 and 4). Note that the angle of the blocking member 42 here refers to the angle when the blocking member 42 is rotated around the second axial direction B1 of the body 422 of the blocking member 42. In this way, the pair of protrusions 462a, 462b that receive the pair of protrusions 421c between them play a role of regulating the rotation angle of the blocking member 42 while allowing the blocking member 42 to slide up and down.

[0043] As shown in Figures 3, 5 to 7, and 8(a) and (c), a trunk insertion hole 48a capable of receiving the trunk 422 of the closing member 42 is formed in the base 482 of the main body 48. The trunk insertion hole 48a is a hole having a cross-sectional shape (here, a substantially rectangular cross-sectional shape) corresponding to the trunk 422, and is formed so as to penetrate the base 482 in the vertical direction. By inserting the trunk 422 into the trunk insertion hole 48a, the closing member 42 is supported by the lock member 41 in a state in which it can slide vertically along the trunk insertion hole 48a.

[0044] As shown in Figs. 3, 4, and 7, spring seats 483 are provided on the upper surface of the base 482, protruding upward from two points around the body insertion hole 48a. Each spring seat 483 has the function of holding the spring 43 attached between the lock member 41 and the blocking member 42 in a fixed position. That is, the spring 43 is attached between the head 421 of the blocking member 42 and the base 482 of the lock member 41 in a state in which the spring 43 surrounds the body 422 of the blocking member 42. At this time, each spring seat 483 abuts against the lower end of the attached spring 43 from the inside (see Fig. 4). This positions the spring 43 and holds it in a fixed position.

[0045] The spring 43 attached in the above manner biases the closing member 42 upward relative to the lock member 41. That is, the closing member 42 is assembled to the lock member 41 in a state in which it is constantly biased upward by the repulsive force of the spring 43. As a result, during normal operation (when the lid is closed) when no lid opening operation, which will be described later, is performed, the head 421 of the closing member 42 is pressed from below against the hole seat 32 of the lid main body 3, thereby maintaining the tool insertion hole 31 of the lid main body 3 in a closed state (see FIG. 1).

[0046] As shown in Figures 3, 7, and 8(a), a pair of first slots 48b are formed in the base 482 of the main body 48 of the lock member 41, the pair being connected to two locations on the outer periphery of the trunk insertion hole 48a. Each of the first slots 48b is a groove dug to a predetermined depth from the upper surface of the base 482. The first slots 48b correspond to the "pin insertion hole" of the present invention.

[0047] The pair of first slots 48b have a shape capable of receiving the pair of pins 423 of the closing member 42. The first slots 48b are formed to extend in a direction intersecting the first axial direction A1 of the lock member 41 in a top view. The angular position of the first slots 48b is shifted from the angular position of the pin 423 (angular position parallel to the first axial direction A1) in a state in which the closing member 42 has been completely assembled to the lock member 41. In other words, the first slots 48b are connected to the barrel insertion hole 48a so as to be capable of receiving the pin 423 in a state in which the closing member 42 has been rotated around the second axial direction B1 of the barrel 422 such that the angular position of the pin 423 is shifted from the angular position parallel to the first axial direction A1.

[0048] 11, a space 48c is formed in the base 482 of the main body 48 of the lock member 41, which is connected to the pair of first slots 48b and allows the pin 423 to move as the body 422 of the closing member 42 rotates about the second axial direction B1. An upper restricting portion 48d is formed in the space 48c, which restricts the pin 423 from moving upward when the body 422 and the pin 423 are inserted into the body insertion hole 48a and the first slot 48b, respectively, and the closing member 42 is pressed down until the pin 423 reaches the space 48c, and then the closing member 42 is rotated about the second axial direction B1 so that the angular position of the pin 423 is parallel to the first axial direction A1.

[0049] 5, 6, and 8(c), a pair of second slots 48e are formed in the base 482 of the main body 48 of the lock member 41. The second slots 48e are connected to two locations on the outer periphery of the trunk insertion hole 48a and connected to the space 48c. Each of the second slots 48e is a groove dug to a predetermined depth from the lower surface of the base 482 to the space 48c.

[0050] The pair of second slots 48e, like the pair of first slots 48b described above, have a shape capable of receiving the pair of pins 423 of the blocking member 42. The second slots 48e are formed to extend in a direction parallel to the first axial direction A1 of the lock member 41 in a bottom view of the lock member 41. The angular position of the second slots 48e corresponds to the angular position of the pin 423 in a state in which the assembly of the blocking member 42 to the lock member 41 is completed. In other words, the second slots 48e are formed to allow the pin 423 to slide downward from the space portion 48c at an angular position where the protruding direction of the pin 423 corresponds to an angular position parallel to the first axial direction A1.

[0051] The first slot 48b and the second slot 48e described above are connected inside the base portion 482 of the main body portion 48 via a space 48c.

[0052] [Assembly procedure] FIG. 10 is a perspective view showing a state when the blocking member 42 is assembled to the lock member 41. As shown in this figure, when assembling the blocking member 42, first, the spring 43 is attached around the body 422. After that, the blocking member 42 is placed above the base 482 of the lock member 41 at an angular position intersecting with the first axial direction A1. Specifically, the position and angle of the blocking member 42 are adjusted so that the second axial direction B1 of the body 422 of the blocking member 42 coincides with the axis of the body insertion hole 48a of the base 482 and the protruding direction of the pin 423 coincides with the extending direction of the first slot 48b. Then, in this state, the blocking member 42 is pushed downward. As a result, the body 422 is inserted into the body insertion hole 48a and the pin 423 is inserted into the first slot 48b. FIG. 11(a) is a schematic diagram showing the state of the body 422 and the pin 423 inserted in this way.

[0053] The blocking member 42 is pushed downward until the pin 423 passes through the first slot 48b and reaches the space 48c. Next, in the state where the pin 423 reaches the space 48c in this way, the blocking member 42 is rotated around the second axial direction B1 of the body 422 until the pin 423 is in an angular position parallel to the first axial direction A1. That is, the blocking member 42 is rotated clockwise by a predetermined angle so that the pin 423 is located below the upper regulating portion 48d of the space. As a result, as shown in FIG. 5 and FIG. 11(b), the pin 423 moves from an angular position where it can slide up and down through the first slot 48b to an angular position where it can slide up and down through the second slot 48e through the space 48c. At this time, since the pin 423 is located below the upper regulating portion 48d, the upward movement of the pin 423 is regulated by the upper regulating portion 48d so that the pin 423 does not come out of the main body 48 of the lock member 41.

[0054] Through such a series of operations, the blocking member 42 is assembled to the lock member 41. That is, the blocking member 42 is assembled to the lock member 41 so as to be slidable in the up and down direction while the upward movement of the pin 423 is restricted so that the pin 423 does not come out of the base 482. In addition, the spring 43 is assembled in a compressed state between the head 421 of the blocking member 42 and the base 482 of the lock member 41.

[0055] [Details of hinge mechanism] FIG. 12 is a cross-sectional view showing the hinge mechanism 5 in a cut plane different from that of the cross-sectional view of FIG. 1, and FIG. 13 is a perspective view of the hinge mechanism 5 (excluding the hinge seat 27 and the claw seat 28) seen obliquely from below. As shown in FIGS. 1, 12, and 13, the hinge mechanism 5 includes a hinge member 51, a pair of engagement claws 52, the hinge seat 27 (FIG. 1), and the claw seat 28 (FIG. 12). The hinge member 51 is a member that connects the lid body 3 to the receiving frame 2. The pair of engagement claws 52 are members that connect the lid body 3 to the receiving frame 2 so that the lid body 3 does not come off from the receiving frame 2 when the internal pressure increases by pressing the lid body 3 upward. The hinge seat 27 has an annular shape through which the hinge member 51 can be inserted, and is a member that is formed integrally with the receiving frame 2. The claw seat 28 is a protrusion that is formed integrally with the receiving frame 2 as an engagement target for the pair of engagement claws 52.

[0056] The hinge member 51 has a support shaft 51a supported by a hinge mounting portion 33 (FIG. 13) formed on the underside of the lid body 3, a link portion 51b extending from the support shaft 51a toward the center of the lid body 3, and a hinge shaft 51c extending from the end of the link portion 51b opposite to the support shaft 51a while curving downward in an arch shape. The hinge shaft 51c is inserted through the annular hinge seat 27. A retaining portion 51d is protruding from the hinge shaft 51c located below the hinge seat 27 when the lid is closed. The retaining portion 51d is a ball-shaped protrusion for preventing the hinge shaft 51c from coming off upward from the hinge seat 27 except in a predetermined state (specifically, a state in which the lid body 3 is opened and rotated approximately 180° in the circumferential direction of the receiving frame 2).

[0057] Each of the pair of engagement claws 52 is attached to an engagement claw attachment portion (not shown) formed on the underside of the lid body 3, and is a member integrally having a base portion 52a protruding downward from the underside of the lid body 3 and an arm portion 52b protruding from the base portion 52a to the radially outward side of the lid body 3. When the lid body 3 is closed to close the upper surface opening 21 of the receiving frame 2, the arm portion 52b is formed to extend from the base portion 52a to a position below the claw receiving seat 28 so that its tip faces the claw receiving seat 28 of the receiving frame 2 in the vertical direction. In addition, each engagement claw 52 is provided so as to leave a predetermined vertical gap between it and the claw receiving seat 28. This gap corresponds to a floating margin Fs (FIG. 17) of the lid body 3 described later.

[0058] The engaging claw 52 in the above position engages with the claw seat 28 of the receiving frame 2 when the internal pressure of the underground structure increases and the lid body 3 is pressed upward (floats). This engagement restricts the lid body 3 from further floating relative to the receiving frame 2. That is, the engaging claw 52 has a function of restricting the amount of floating of the lid body 3 due to the internal pressure increase to a predetermined amount (floating allowance Fs) or less. Also, as described above, the hinge member 51 is inserted into the hinge seat 27 in a state where it is restricted so as not to come out of the hinge seat 27. In other words, the combination of the hinge member 51 and the engaging claw 52 has a function of restraining the lid body 3 to the receiving frame 2 at a position away from the lock member 41. Such a combination of the hinge member 51 and the engaging claw 52 corresponds to the "second connecting member" in this invention.

[0059] Here, when the lid body 3 is pressed upward (floats) due to an increase in the internal pressure of the underground structure or the like, the pair of engaging claws 52 engage with the claw seats 28, and various forces such as tension, compression, and bending act on each engaging claw 52. When these forces become large, at least one of the pair of engaging claws 52 breaks. In this specification, the force that breaks the engaging claws 52 is defined as the breaking strength of the engaging claws 52. The breaking strength of the engaging claws 52 is greater than the breaking strength of the locking member 41 described above.

[0060] That is, in this embodiment, grooves 47 for reducing the breaking strength are formed in the connection portion 46 of the lock member 41, specifically, the first groove 47a is formed in the first wall portion 46a, and the second groove 47b is formed in the second wall portion 46b, so that the breaking strength of the lock member 41 is made smaller than the breaking strength of the engagement claw 52. Such a difference in breaking strength can be created by appropriately adjusting the depth and width of the grooves 47 (47a, 47b). The breaking strength of the lock member 41 corresponds to the "breaking strength of the first connecting member" in this invention, and the breaking strength of the engagement claw 52 corresponds to the "breaking strength of the second connecting member" in this invention.

[0061] [Lid opening operation] Next, the procedure of the lid opening operation for opening the lid main body 3 will be described. As shown in FIG. 14, a dedicated opening / closing tool 100 is used for the lid opening operation. The opening / closing tool 100 has a substantially T-shaped tip 100a. The operator first inserts the tip 100a of the opening / closing tool 100 into the tool insertion hole 31 of the lid main body 3 from the outside (upper side). The tip 100a inserted into the tool insertion hole 31 abuts against the head 421 of the blocking member 42 blocking the tool insertion hole 31 from the lower side, and presses the head 421 downward. As a result, as shown in FIG. 14, the blocking member 42 is pressed downward against the repulsive force of the spring 43, and the head 421 (seat portion 421b) is separated downward from the hole seat 32 of the tool insertion hole 31.

[0062] Next, the operator rotates the opening / closing tool 100, and then moves it radially outward from the lid body 3 so that the substantially T-shaped tip 100a is in the position shown in FIG. 15. This causes the lock member 41 to swing in a direction in which the engagement portion 481 moves away from the lock receiving seat 26 of the receiving frame 2. That is, the lock member 41 swings in the direction shown by the arrow C1 in FIG. 15, with the shaft portion 451 (451a, 451b) connected to the lower surface portion of the lid body 3 as a fulcrum. As a result of this swing, the engagement portion 481 moves to a position where it does not engage with the lock receiving seat 26, and the lock mechanism 4 is unlocked. Next, the operator tilts the opening / closing tool 100 in the direction shown by the arrow C2 in FIG. 15. This releases the engagement between the lid body 3 and the receiving frame 2.

[0063] Next, the worker pulls up the opening / closing tool 100 obliquely upward while maintaining the unlocked state of the lock mechanism 4. This allows the lid main body 3 to be pulled out onto the ground, as shown in FIG.

[0064] [Effects when internal pressure increases] Next, the action when the internal pressure of the underground structure rises will be described. When the internal pressure of the underground structure rises due to the inflow of rainwater, etc., this increased internal pressure presses the lid body 3 upward, causing the lid body 3 to rise. FIG. 17 is a cross-sectional view showing the state in which the lid body 3 has risen in this way. As shown in this figure, as the lid body 3 rises, the engagement portion 481 of the lock member 41 engages with the lock receiving seat 26 of the receiving frame 2, and the engagement claw 52 of the hinge mechanism 5 engages with the claw receiving seat 28 of the receiving frame 2. This engagement restricts the lid body 3 from rising any further. In other words, the lid body 3 is held by the receiving frame 2 in a state where it is raised by a certain amount of floating allowance Fs, and the lid body 3 is prevented from coming off the receiving frame 2.

[0065] The floating of the lid body 3 as described above releases the internal pressure from the gap between the lid body 3 and the receiving frame 2, decreasing the internal pressure. When the internal pressure decreases, the lid body 3 returns to its original closed position, that is, to a position where it fits into the lid support portion 25 of the receiving frame 2 (see FIG. 1).

[0066] Here, for example, if a large amount of rainwater flows into the underground structure due to heavy rain, etc., and the internal pressure rises suddenly, the internal pressure may not be released even if the lid body 3 rises by the floating allowance Fs (to the limit). In such a case, the lid body 3 is pressed further upward in a state in which the locking member 41 and the engaging claw 52 are engaged with the receiving frame 2, that is, in a state in which the lid body 3 is connected to the receiving frame 2 by the locking member 41 and the engaging claw 52. When the lid body 3 is pressed upward, a force that pulls the receiving frame 2 upward acts on the receiving frame 2 from the lid body 3. At this time, if the connection by the locking member 41 and the engaging claw 52 is unlimited, the force that pulls the receiving frame 2 upward increases to a level that exceeds the connection strength between the receiving frame 2 and the underground structure, that is, the guaranteed strength of the bolt that connects the receiving frame 2 to the underground structure, and the receiving frame 2 may come off the underground structure.

[0067] In order to deal with the above-mentioned problems, in this embodiment, a first groove 47a is formed on the outer peripheral surface of the first wall portion 46a of the locking member 41, and a second groove 47b is formed on the outer peripheral surface of the second wall portion 46b. Since the first groove 47a and the second groove 47b cause a decrease in strength of the locking member 41, the grooves 47 (47a, 47b) are formed on the outer peripheral surface 461 of the connection portion 46 of the locking member 41, so that the breaking strength of the locking member 41 can be reduced to be lower than the breaking strength of the engagement claw 52. Therefore, before the receiving frame 2 is detached from the underground structure, the locking member 41 can be broken before the engagement claw 52, ​​and the internal pressure can be released. Specifically, as shown in FIG. 18, the cover body 3 rotates with the hinge member 51 as a fulcrum, and the upper opening 21 of the receiving frame 2 is opened, and the internal pressure can be released from the upper opening 21. In this way, the internal pressure can be released while maintaining the connection between the lid body 3 and the receiving frame 2 via the hinge member 51, so that the lid body can be prevented from coming off the receiving frame even if the internal pressure suddenly increases. Also, as described above, the receiving frame 2 is no longer pulled strongly upward, so that the receiving frame 2 can be prevented from coming off the underground structure.

[0068] Furthermore, the recessed groove 47 formed on the outer peripheral surface 461 of the lock member 41 (connection portion 46) is formed along a plane parallel to the first axial direction A1, so that the direction in which the lid body 3 is pressed upward intersects with the direction in which the groove is formed. Therefore, when the internal pressure suddenly increases, stress concentration occurs in the recessed groove 47, making it easier to break the first connecting member (lock member 41) before the second connecting member (hinge member 51 and engagement claw 52).

[0069] [Other effects] Next, other effects based on the configuration of this embodiment will be described. In this embodiment, the groove 47 is formed in a rectangular cross section with a substantially flat bottom surface, so that excessive stress concentration is less likely to occur compared to, for example, a V-shaped cross section of the groove. This makes it possible to stably obtain the effect of lowering the breaking strength of the lock member 41 below the breaking strength of the engagement claw 52, ​​and makes it easier to keep the breaking strength of the lock member 41 close to the target value.

[0070] In addition, in this embodiment, the connection portion 46 of the lock member 41 includes a first wall portion 46a connecting the main body portion 48 and the first shaft portion 451a, and a second wall portion 46b connecting the main body portion 48 and the second shaft portion 451b, and a first groove 47a is formed in the first wall portion 46a and a second groove 47b is formed in the second wall portion 46b, so that at least one of the first wall portion 46a and the second wall portion 46b can be broken in the event of a sudden rise in internal pressure.

[0071] In this embodiment, the tool insertion hole 31 for inserting the opening / closing tool 100 is formed in the lid body 3, and the blocking member 42 capable of blocking the tool insertion hole 31 is assembled to the lock member 41 so as to be slidable in the vertical direction. With this configuration, it is possible to prevent rainwater and the like from flowing into the underground structure through the tool insertion hole 31 when the lid is closed. Also, the blocking member 42 is pushed downward only when necessary to open the tool insertion hole 31, and in this state, the lid body can be opened and closed. Furthermore, since the blocking member 42 is disposed between the first wall portion 46a and the second wall portion 46b, and the groove 47 is not formed in the mutually opposing portions of the first groove 47a and the second wall portion 46b (i.e., the groove 47 is formed in the mutually non-opposing portions), it is possible to prevent the blocking member 42 from getting caught in the groove 47 when the blocking member 42 slides in the vertical direction, and the blocking member 42 can be smoothly slid in the vertical direction.

[0072] [Variations] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the following modifications may be made.

[0073] In the above embodiment, the lock member 41 is formed with two connection parts 46 (first wall part 46a and second wall part 46b), and the outer peripheral surface 461 of each wall part is formed with the groove 47 (first groove 47a and second groove 47b), but this is not limiting, and for example, the groove 47 may be formed only in the outer peripheral surface 461 of either the first wall part 46a or the second wall part 46b. Also, the lock member 41 may be formed with only one connection part 46.

[0074] In the above embodiment, the first groove 47a and the second groove 47b are formed along a plane parallel to the first axial direction A1, but this is not limited thereto, and for example, the grooves may be formed along a plane parallel to a direction that intersects the first axial direction A1 at a predetermined angle.

[0075] In the above embodiment, a groove 47 having a rectangular cross section and a substantially flat bottom surface 471 is formed in the lock member 41, but instead, a groove having, for example, an arc-shaped bottom surface may be formed in the lock member 41.

[0076] In the above embodiment, a pair (two) of pins 423 are formed at the lower end of the body 422 of the blocking member 42, but this is not limited to this, and one or more than three pins may be formed, and the pins may be formed at a location other than the lower end of the body 422.

[0077] In the above embodiment, the second slot 48e is formed in the base 482 of the lock member 41, but the second slot 48e is not essential. For example, the vertical dimension (thickness) of the base 482 may be reduced, and the first slot 48b may be formed to penetrate the base 482, and the second slot 48e may be omitted.

[0078] In the above embodiment, the combination of hinge member 51 and engagement claw 52 is equivalent to the second connecting member, but this is not limited thereto. For example, a portion capable of performing a function similar to that of engagement claw 52 may be integrally formed in hinge member 51, and the second connecting member may be composed of hinge member 51 alone, with engagement claw 52 being omitted. [Explanation of symbols]

[0079] 1 Lid for underground structures 2. Receiving slots 21 Top opening 3 Lid body 4 Locking mechanism 41 Lock member (first connecting member) 45 Supported part 451 Shaft A1 First axial direction 46 Connection 461 Outer surface 47 Groove A11: Plane parallel to the first axis direction 48 Main body 481 Engagement part 482 Base 48a Body insertion hole 48b First slot (pin insertion hole) 48c space section 48d Upper Regulation Department 42 Closure member 421 Head 422 Torso B1 Second axial direction 423 Pin 43 Spring 5 Hinge mechanism 51 Hinge member (second connecting member) 52 Engagement claw (second connecting member) 100 Opening and closing tools

Claims

1. A frame fixed to an upper end of the underground structure; a lid body that closes the top opening of the receiving frame in an openable and closable manner; a first connecting member that connects the lid body to the receiving frame so that the lid body does not come off from the receiving frame when the internal pressure increases and the lid body is pressed upward; a second connecting member that connects the lid body to the receiving frame at a position away from the first connecting member; The first connecting member includes a main body portion, a supported portion supported by a lower surface portion of the lid main body, and a connecting portion connecting the main body portion and the supported portion, The supported portion includes a shaft portion that is connected to a lower surface portion of the lid body and has a first axial direction, A lid for underground structures, wherein the connection portion includes an outer peripheral surface and a groove formed in the outer peripheral surface so that the breaking strength of the first connecting member is smaller than the breaking strength of the second connecting member.

2. The underground structure cover according to claim 1, The concave groove is a groove having a substantially flat bottom surface and a rectangular cross section, and is a cover for an underground structure.

3. The underground structure cover according to claim 1, The recessed groove includes a groove formed along a plane parallel to the first axial direction. Lid for underground structures.

4. The underground structure cover according to any one of claims 1 to 3, The shaft portion includes a first shaft portion and a second shaft portion opposed to each other in the first axial direction, the connection portion includes a first wall portion connecting the main body portion and the first shaft portion and a second wall portion connecting the main body portion and the second shaft portion, A cover for an underground structure, wherein the groove includes a first groove formed in the first wall portion and a second groove formed in the second wall portion.

5. The underground structure cover according to claim 4, The cover further includes a closing member that closes a tool insertion hole formed in the cover body from below the cover body to allow insertion of an opening / closing tool, the blocking member is supported by the first connecting member so as to be slidable in the up-down direction between the first wall portion and the second wall portion, the first recessed groove is a groove formed in a portion of the first wall portion not facing the second wall portion, A cover for an underground structure, wherein the second recessed groove is a groove formed in a portion of the second wall portion that does not face the first wall portion.

6. The underground structure cover according to claim 5, the closing member includes a head portion that closes the tool insertion hole from the underside of the lid body, a body portion that extends from the head portion in a second axial direction, and a pin that projects in a direction intersecting with the second axial direction, the main body portion of the first connecting member includes a trunk portion insertion hole through which the trunk portion can slide in a vertical direction, a pin insertion hole through which the pin can slide in a vertical direction, and a space portion through which the pin can move in association with rotation of the trunk portion about the second axial direction, A lid for underground structures, wherein the space portion has an upward regulating portion that regulates the upward movement of the pin.

Images