JP4855365B2 - Fall prevention device for underground structures - Google Patents

Description

  The present invention relates to a fall prevention device for an underground structure including a receiving frame on which a lid for an underground structure can be placed, and a fall prevention ladder provided so as to be raised and lowered with respect to the receiving frame. Underground structures include what are generally called manholes, such as underground buried objects in sewers, large iron lids that block openings through underground structures, etc., sewage culverts, and underground power and communications. As an openable and closable iron cover for protection of facility equipment and underground cables, an iron cover for power transmission, a power distribution cover, a buried conduit under the road surface in waterworks and gas pipes, and an open / close door that connects the accessory to the ground A general term for a fire hydrant lid, a water control valve lid, a gate valve lid, a gas valve lid, a gas pipe lid, a water meter lid, etc., and a receiving frame that supports these lids.

  As a safety measure for the opening of the underground structure, it has a fall prevention ladder that functions as an inner lid that prevents a person from falling when the lid for the underground structure is opened, and functions as a handheld when an operator moves up and down. For underground structures that have a locking function against internal pressure in order to prevent the fall prevention ladder as an inner lid from floating even if there is a fall prevention device for underground structures and sewage increases in the underground structure A fall prevention device is desired.

Regarding a conventional fall prevention device for an underground structure of this type, there is known a lock device that attaches a movable lock pin to a fall prevention ladder and locks it to a receiving frame for an underground structure (for example, see Patent Document 1). . However, in the above-described locking device, when opening the ladder for preventing the fall, the worker first moves the lock pin located on the tip side of the ladder to release the lock, and then releases the side of the ladder. It is necessary to enter the underground structure using a scaffold provided in the underground structure on the base end side of the ladder, and the work efficiency is not good. Workers who have come out of the underground structure have to close the ladder from the side, move to the tip side and manually lock it, and work efficiency is similarly poor. Also, in order to stably lock against internal pressure, it is preferable to provide locks at both ends of the fall prevention ladder, that is, at two locations. If you try to open the fall prevention ladder with the lock on the tip side unlocked, it is necessary to approach the opening as the fall prevention ladder rises. Is difficult. If the worker who unlocks the lock pin on the tip side of the fall prevention ladder and the worker who opens the fall prevention ladder on the side are separated, the working efficiency is further improved.
JP 2002-371575 A

  The present invention has been made to solve such a problem, and when the fall-preventing ladder is closed, it is securely locked against the internal pressure of the underground structure, and when the fall-preventing ladder is opened or closed, It is an object of the present invention to provide a fall prevention device for an underground structure that can efficiently perform undulation work at a safe position that is difficult to fall down.

  In order to achieve the above object, the invention according to claim 1 is provided with a receiving frame on which a lid for an underground structure can be placed, a support shaft on the base end side, and the support frame can be raised and lowered around the support shaft A fall prevention device for an underground structure provided with a fall prevention ladder, wherein the receiving frame has a stopper projecting on an inner peripheral surface, and the fall prevention ladder is an axis of the support shaft. A protruding end that is slidable in the direction and supported by the upper surface of the stopper in a lying state, and an engaging portion that engages with the lower surface of the stopper below the protruding end. The engagement is held by the urging force and can be released by sliding in a direction against the urging force when standing up.

  According to a second aspect of the present invention, in the fall prevention device for an underground structure according to the first aspect, a tapered surface is formed at a lower portion of the engaging portion, and the fall prevention ladder is When the taper surface slides in a direction against the urging force by a contact force that slides against the stopper, the engagement portion engages with the stopper when the engagement portion passes through the stopper and the overturning is completed. To match.

  According to a third aspect of the present invention, in the fall prevention device for an underground structure according to the first or second aspect, the ladder frame of the fall prevention ladder has a long hole formed in the longitudinal direction on the base end side. The support shaft is inserted into the elongated hole, and the support shaft is supported at a position lower than the attachment portion by a support bearing portion provided on an attachment portion formed to project from the inner peripheral surface of the receiving frame. When the falling prevention ladder is erected, the ladder frame is inclined toward the attachment portion, the ladder frame comes into contact with the attachment portion and descends, and the gap between the contact surface of the ladder frame and the elongated hole Is spread continuously toward the front end side of the ladder frame, and the ladder frame is sandwiched between the support shaft and the lower part of the support bearing portion by a wedge effect so that the falling prevention ladder is in an upright state. When the fall prevention ladder is held down, the support shaft is on the proximal end side of the long hole. By increasing the state located at the edge, and serves as a rotatable lodging direction.

  According to a fourth aspect of the present invention, in the fall prevention device for an underground structure according to the third aspect, the elastic body is a spring that has one end pressed against the support bearing portion and biases the support shaft. It is.

  According to a fifth aspect of the present invention, in the fall prevention device for an underground structure according to the third or fourth aspect, the ladder for fall prevention is arranged in parallel with a side frame projecting outward from the ladder frame. It is what has been.

  According to the first aspect of the present invention, it is possible to prevent a person from falling into the underground structure in a lying state with the fall-preventing ladder closed, and to be reliably locked against the internal pressure of the underground structure, thereby preventing the falling. When opening or standing the ladder, the operator can release the lock by sliding the entire fall prevention ladder from the side of the fall prevention ladder and remain in the same safe standing position that is difficult to fall. What is necessary is just to make the fall prevention ladder stand up, and it can continue to enter an underground structure as continuous operation | work, and can work safely and efficiently.

  According to the second aspect of the present invention, the fall prevention ladder is automatically locked with respect to the receiving frame when the fall prevention ladder is closed, that is, laid down, so that the locking reliability is maintained. , Can improve the work efficiency safely.

  According to the third aspect of the present invention, the fall prevention ladder is held in the open standing state by the wedge effect, so that the fall prevention ladder can be held by a worker when the worker moves up and down.

  According to the fourth aspect of the present invention, the fall prevention ladder can reliably hold the locked state to the receiving frame by the spring in the closed lying state.

  According to the fifth aspect of the present invention, since the side frame closes the opening of the underground structure in the lying state where the fall prevention ladder is closed, the human fall prevention effect can be further enhanced. Moreover, since the side frame serves as a handle when the fall prevention ladder is slid or raised, work efficiency can be further improved.

  Hereinafter, the whole structure of the fall prevention apparatus for underground structures which concerns on the 1st Embodiment of this invention is demonstrated with reference to FIG. The fall prevention device 1 for an underground structure includes a receiving frame 10 and a fall prevention ladder 20 inside thereof, and is installed at an opening of an underground structure (not shown). The receiving frame 10 is for placing a disc-shaped lid for an underground structure (not shown), and FIG. 1 is a plan view of the receiving frame 10 with the lid open. The fall prevention ladder 20 includes a ladder step 28 between the ladder frames 25 on both sides, and closes the opening of the underground structure to prevent a person from falling. The number of steps of the ladder steps 28 is not limited, and may be provided at an interval that can prevent a person from falling. The middle of each of the plurality of ladder steps 28 may be connected to the ladder frame 25 with a beam substantially parallel to increase the load bearing strength of the fall prevention ladder 20.

  The fall and standing of the fall prevention ladder 20 of the apparatus will be described with reference to FIG. 2A. The fall prevention ladder 20 includes a support shaft 21 on the base end side, and the support shaft 21 is pivotally provided on the receiving frame 10. The fall-preventing ladder 20 can be rotated around the support shaft 21 in the lying down direction and the standing direction. The ladder stage 28 prevents a person from falling when the fall-preventing ladder 20 is lying down, and is used to lift and lower the operator when standing.

  A lock in the fall state of the fall prevention ladder 20 will be described with reference to FIGS. In the fall-down ladder 20, the fall preventing ladder 20 has a protruding end portion 22 protruding above the tip end side of the ladder frame 25, and an engaging portion 23 protruding below the protruding end portion 22 at an interval. A stopper 12 protrudes from the inner peripheral surface 11 of the receiving frame 10 in a substantially horizontal inward direction, and the stopper 12 supports the protruding end 22 in a state where the falling prevention ladder 20 is lying down. The front end side of the ladder 20 is supported by the receiving frame 10. The stopper 12 engages with the engaging portion 23 at the same time, and even if an internal pressure is generated in the underground structure and buoyancy is applied to the fall prevention ladder 20, the fall prevention ladder 20 is prevented from rising and opening. And prevent people from falling. The vertical interval between the projecting end portion 22 and the engaging portion 23 is an interval that allows the stopper 12 to be sandwiched. The fall prevention ladder 20 is locked to the stopper 12 by the pinching of the stopper 12 by the protruding end portion 22 and the engaging portion 23. This lock is held by the urging force of the elastic body 24, and the state where the fall prevention ladder 20 is locked with respect to the receiving frame 10 is held. Note that the projecting end portion 22 and the engagement portion 23 are fixed to the ladder frame 25, have no movable portion, have a simple structure, and contribute to cost reduction.

  Release of the lock when raising the fall prevention ladder 20 will be described with reference to FIGS. 4 and 5. FIG. As shown in FIG. 4, the fall prevention ladder 20 is slidable in the axial direction of the support shaft 21. In the conventional fall prevention ladder, the worker opens from the front end side. However, in the fall prevention ladder 20 of the present invention, the worker slides the entire fall prevention ladder 20 from the side and locks it. Release and turn to stand from the side. In FIG. 5, in the lying down state, the stopper 12 and the engaging portion 23 are in a position where they are engaged and are in a locked state. When raising the fall prevention ladder 20, the engagement between the stopper 12 and the engagement portion 23 is released by sliding the entire fall prevention ladder 20 in a direction against the urging force of the elastic body 24. That is, the receiving frame 10 of the fall prevention ladder 20 is unlocked. By constructing the fall prevention device 1 for an underground structure in this way, one worker slides the fall prevention ladder 20 from the side, and then the fall prevention ladder 20 without changing the standing position. It is possible to stand up and subsequently enter the underground structure as a continuous operation, and work efficiently. Further, the fall prevention ladder 20 may be pulled and slid from the side in a direction away from the opening, and there is no possibility that the worker falls into the opening. Further, it is not necessary to approach the opening according to the standing of the fall-preventing ladder 20, and the standing work can be performed at a safe position where it is difficult to fall. A scaffold (not shown) is provided on the inner side below the opening of the underground structure on the base end side, and the worker enters the underground structure using the scaffold.

  Next, automatic locking when the fall prevention ladder 20 is laid down will be described with reference to FIGS. 6A to 6F. In FIG. 6A, the fall prevention ladder 20 rotates in the lying down direction, and the engaging portion 23 approaches from above the stopper 12. In FIG. 6B, the engaging portion 23 further approaches the stopper 12, and an oblique tapered surface 231 formed at the lower portion of the engaging portion 23 contacts the stopper 12. In FIG. 6C, the tapered surface 231 and the stopper 12 slide in contact with each other. The side where the stopper 12 contacts the tapered surface 231 is chamfered so as to facilitate sliding. A contact force is generated between the tapered surface 231 and the stopper 12. This contact force is due to the weight of the fall prevention ladder 20 and the inertial force of rotation. The fall prevention ladder 20 is rotated in the lying down direction while sliding in a direction against the urging force of the elastic body 24 by the contact force. In FIG. 6D, the engagement portion 23 passes downward while contacting the side surface with respect to the stopper 12. In FIG. 6E, the engagement portion 23 passes through the stopper 12, and the fall prevention ladder 20 slides in the urging direction by the urging force of the elastic body 24. In FIG. 6F, the fall of the fall prevention ladder 20 is completed, the engaging portion 23 engages with the stopper 12, and the fall prevention ladder 20 is automatically locked with respect to the receiving frame 10. The fall prevention ladder 20 is kept locked by the urging force of the elastic body 24. At the same time, the protruding end 22 is supported by the stopper 12. In addition, the upper surface of the stopper 12 is formed with a concave portion 121 having a shape corresponding to the shape of the lower surface of the projecting end portion 22, which contributes to the automatic positioning of the fall-preventing ladder 20 and the holding of the locked state. . The recess 121 is chamfered to prevent the protrusion 22 from being caught when sliding on the stopper 12 from the inside to the outside of the recess 121. A convex portion for positioning the fall prevention ladder 20 may be provided on the stopper 12 instead of the concave portion 121. As described above, the fall prevention ladder 20 slides temporarily and automatically in the unlocking direction when falling down, and automatically returns to the locking direction and locks against the receiving frame when the falling down is completed. Therefore, it can efficiently fall down and lock securely. In addition, the worker does not need to approach the opening having the stopper and is safe.

  The structure of the base end side of the fall prevention ladder 20 will be described with reference to the drawings. The entire fall prevention ladder 20 is slidable in the axial direction of the support shaft 21. In addition, the fall prevention ladder 20 is held by the worker when the worker falls up and down, so that the standing state needs to be stably maintained. In FIG. 8A, a long hole 26 is formed in the longitudinal direction on the base end side of the ladder frame 25 of the fall prevention ladder 20. The support shaft 21 is inserted through the long hole 26. An attachment portion 13 is formed so as to protrude from the inner peripheral surface 11 of the receiving frame 10, and a support bearing portion 14 is provided on the lower surface of the end of the attachment portion 13, and the support bearing portion 14 is lower than the attachment portion 13. Receive 21. In FIG. 7, the support bearing part 14 is provided with a bearing plate 142 having a shaft hole 144 at an end protruding to the tip side and a side plate 143 not having the shaft hole 144 on a flat support bearing part lower part 141. ing. The bearing plate 142 slidably receives the support shaft 21. The reason for not using the bearing plates 142 on both sides is to allow the fall prevention ladder 20 to slide. A convex portion 147 that engages with the end portion of the mounting portion 13 is formed on the upper end of the bearing plate 142 and the side plate 143, and a convex portion 146 that engages with a concave portion formed on the lower surface of the mounting portion 13 on the opposite upper side. Is formed. The support bearing portion 14 has a bolt hole 145 in the support bearing portion lower portion 141 and is bolted to the attachment portion 13. Note that the support bearing portion 14 may be integrally formed with the attachment portion 13. Each of the ladder frames 25 abuts on the same side of each of the two bearing plates 142, the support shaft 21 is urged toward the bearing plates 142 by the elastic body 24, and the ladder frame 25 is separated from the bearing plates 142. , The ladder frame 25 moves away from the bearing plate 142 against the urging force of the elastic body 24. The ladder frame 25 is in contact with the side of the bearing plate 142 in FIG. 1, and slides in the direction of the arrow away from the bearing plate 142 in FIG. When the ladder frame 25 is configured to contact the side of the bearing plate opposite to the side shown in FIG. 4, it slides in the direction opposite to the arrow in FIG. By this slide, the protruding end portion 22 and the engaging portion 23 on the front end side of the ladder frame 25 are separated from the stopper 12 and the lock is released.

  Next, the standing operation and holding of the standing state of the fall prevention ladder 20 will be described with reference to FIGS. 8A to 8D. In FIG. 8A, the worker rotates the fall prevention ladder 20 around the support shaft 21 in the upright direction, whereby the ladder frame 25 approaches the mounting portion 13. In FIG. 8B, the ladder frame 25 abuts on the attachment portion 13. At this time, the fall prevention ladder 20 is inclined toward the mounting portion 13. In FIG. 8C, the ladder frame 25 is lowered by its own weight while being in contact with the attachment portion 13. The support shaft 21 moves from the proximal end side of the long hole 26 to the distal end side. In FIG. 8D, the space | interval of the surface and contact | abutting with the attaching part 13 of the ladder frame 25 and the long hole 26 has spread continuously toward the front end side of the ladder frame 25, and the ladder frame 25 is the spindle 21. And the support bearing portion lower portion 141 of the support bearing portion 14 by a wedge effect. Furthermore, the ladder frame 25 is also supported by contact with the mounting portion 13. Therefore, the fall prevention ladder 20 is stably maintained in an upright state, and does not fall down even if an operator uses it on hand.

  The operation of causing the fall prevention ladder 20 to fall from the standing state will be described with reference to FIGS. 9A to 9D. In FIG. 9A, the fall prevention ladder 20 is held in an upright state by the wedge effect of the ladder frame 25. In FIG. 9B, when the fall prevention ladder 20 is raised against the wedge effect and gravity, the ladder frame 25 rises with the wedge effect between the support shaft 21 and the support bearing portion lower portion 141 eliminated. The support shaft 21 moves from the distal end side of the elongated hole 26 to the proximal end side. In the middle of ascending, the ladder frame 25 interferes with the support bearing portion 14 and cannot rotate. In FIG. 9C, the support shaft 21 is positioned on the proximal end side of the long hole 26, and the ladder frame 25 stops rising. In FIG. 9D, the ladder frame 25 can be rotated without interfering with the support bearing portion 14, and therefore the fall prevention ladder 20 can be rotated in the lying down direction.

  The support bearing portion 14 can also be used to hold one end of the elastic body 24. The support shaft 21 is formed with a small diameter portion having a small shaft diameter in a region of one end, and a cylindrical elastic body 24 is provided in the small diameter portion. One end of the elastic body 24 is pressed against the support bearing portion 14 and is fixed to the attachment portion 13 of the receiving frame 10 via the support bearing portion 14, and the other end biases the support shaft 21. The position where the elastic body 24 is provided may be either one of both ends of the support shaft 21, and which end is not limited. The material of the elastic body 24 may be, for example, an elastic resin and is not limited. However, for example, a metal spring is preferable from the viewpoint of cost and the like.

  The production method of the fall prevention device for an underground structure according to the present invention is not limited. For example, as shown in FIG. 1, the engaging portion 23, the ladder frame 25, the ladder step 28, and the like of the fall prevention ladder 20 may be integrally formed by casting. Low cost manufacturing is possible by integral molding. Further, for example, as shown in FIG. 10, in the fall prevention device 2 for underground structures, the engaging portion 33, the ladder frame 35, the ladder step 38, etc. of the fall prevention ladder 30 are used as individual constituent members such as bolts or rivets. You may manufacture by fastening with a fastening means. Thereby, for example, a material that is excellent in corrosion resistance but difficult to cast, such as stainless steel, can be used as a constituent member, and a material having corrosion resistance according to the use environment is used in a severe use environment due to salt damage or the like. be able to.

  The whole structure of the fall prevention apparatus for underground structures which concerns on the 2nd Embodiment of this invention is demonstrated with reference to drawing 11. FIG. A side frame 29 is juxtaposed to the outside of the ladder frame 25 of the fall prevention ladder 20. Since the side frame 29 further closes the opening of the fall prevention device 3 for underground structures, it is possible to more reliably prevent a person from falling. Further, since the side frame 29 serves as a handle when the fall prevention ladder 20 is raised and lowered, the raising and lowering work can be made more efficient. The side frame 29 may be integrally formed with the ladder frame 25.

  The method of fixing the side frame to the ladder frame is not limited, and the side frame 39 may be bolted to the ladder frame 35 as shown in FIG.

  The present invention is not limited to the configuration of each of the embodiments described above, and various modifications can be made without departing from the scope of the invention. For example, the constituent member of the fall prevention ladder is not limited to metal, and may be fiber reinforced resin. Further, the planar shape of the ladder frame is not limited to a linear shape, and may be a curved shape such as an arc.

The top view of the fall prevention apparatus for underground structures which concerns on the 1st Embodiment of this invention. 2A is a side view of one of the fall prevention ladders in the apparatus, and FIG. 2B is a side view of the other of the ladders. The front view of the front end side of the ladder. The top view of the apparatus of the state which slid the ladder. The front view of the front end side of the ladder explaining a locked state and an unlocked state. 6A to 6F are cross-sectional views taken along the line XX of FIG. 1 and illustrating a tipping side of the ladder. The perspective view of the support bearing part of the same apparatus. FIG. 8A to FIG. 8D are cross-sectional views on the base end side for explaining the standing operation of the ladder. FIG. 9A to FIG. 9D are cross-sectional views on the base end side for explaining the folding operation of the ladder. The top view of the fall prevention apparatus for underground structures which concerns on the modification of the 1st Embodiment of this invention. The top view of the fall prevention apparatus for underground structures which concerns on the 2nd Embodiment of this invention. The top view of the fall prevention apparatus for underground structures which concerns on the modification of the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fall prevention device 10 for underground structures 11 Receiving frame 11 Inner peripheral surface 12 Stopper 13 Attachment part 14 Support bearing part 20 Fall prevention ladder 21 Support shaft 22 Protruding end part 23 Engagement part 231 Tapered surface 24 Elastic body 25 Ladder frame 26 Long hole 29 Side frame 39 Side frame

Claims (5)

A receiving frame on which a lid for an underground structure can be placed;
A fall prevention device for an underground structure comprising a support shaft on the base end side, and a fall prevention ladder pivotally provided on the receiving frame so as to be able to undulate around the support shaft,
The receiving frame has a stopper projecting on the inner peripheral surface,
The fall prevention ladder is slidable in the axial direction of the support shaft, and engages with a projecting end portion supported by the upper surface of the stopper in a lying state and a lower surface of the stopper below the projecting end portion. The engagement portion is held by the urging force of the elastic body, and when erected, the engagement can be released by sliding in a direction against the urging force. A fall prevention device for underground structures. A tapered surface is formed at the lower portion of the engaging portion,
When the fall prevention ladder falls down, the taper surface slides in a direction against the urging force by a contact force that contacts and slides against the stopper, and the engagement portion passes through the stopper and falls down. 2. The fall prevention device for an underground structure according to claim 1, wherein the engaging portion engages with the stopper when completed. In the ladder frame of the fall prevention ladder, a long hole is formed in the longitudinal direction on the base end side,
The support shaft is inserted into the elongated hole,
The support shaft is supported at a position lower than the attachment portion by a support bearing portion provided in an attachment portion formed to protrude from the inner peripheral surface of the receiving frame,
When the fall prevention ladder is set up, it is inclined toward the mounting portion, and the ladder frame is lowered in contact with the mounting portion,
The interval between the surface on the contact side of the ladder frame and the long hole continuously extends toward the tip side of the ladder frame,
The ladder frame is sandwiched between the support shaft and the lower portion of the support bearing portion by a wedge effect to maintain the standing state of the fall prevention ladder,
The fall prevention ladder can be rotated in a fall direction by raising the support shaft to a state of being located at an end on a proximal end side of the long hole when lying down. The fall prevention device for underground structures according to claim 1 or claim 2.   The fall prevention device for an underground structure according to claim 3, wherein the elastic body is a spring whose one end is pressed against the support bearing portion and biases the support shaft.   5. The fall prevention device for an underground structure according to claim 3, wherein the fall prevention ladder has a side frame further jutting out outward from the ladder frame.

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