JP2012152316A - Fall prevention equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide fall prevention equipment for giving desired rotary resistance to a drum without any special adjustment and reliably preventing fall and absorbing shock.SOLUTION: A drum 4 and a ratchet wheel 7 are screw-coupled via a screw part 22b of a hollow cylinder 22. At the connection part, shock absorption members 26, 27 are inserted between the drum 4 and the ratchet wheel 7. When torque in the direction of drawing a lifeline 5 acts on the drum 4 with the ratchet wheel 7 locked by a lock nail 8, the drum 4 approaches the ratchet wheel 7 in the axis direction, and the shock absorption members 26, 27 are compressed and crushed.

Description

  The present invention relates to a fall-preventing device used in high-altitude work such as a construction site.

  2. Description of the Related Art Conventionally, in high-altitude work at a construction site or the like, an instrument that prevents a crash when an operator steps off is used. For example, the crash prevention device of Patent Document 1 includes a drum that is housed in a case and winds up a lifeline, a spring that biases the drum in the winding direction, and a ratchet wheel (ratchet internal gear) that is fixed in the case. And a locking claw that is provided on the drum and engages with the ratchet teeth of the ratchet wheel to lock the rotation of the ratchet wheel. In this fall prevention device, when the lifeline is pulled out of the case at a relatively slow speed during normal work, the lock claw does not engage with the ratchet teeth of the ratchet wheel, and the rotation of the drum is not locked. However, when an operator falls from a high place and the lifeline is pulled out rapidly, the lock claw engages with the ratchet teeth of the ratchet wheel, and the rotation of the drum is quickly locked. Loss of workers is prevented.

  By the way, in the fall prevention device as described above, when the rotation of the drum is locked by the lock claw when the worker is dropped, the pulling out of the lifeline stops suddenly, so that a big impact acts on the worker. In particular, when the lifeline is a non-stretchable wire rope, since the lifeline itself cannot absorb the impact, the impact acts on the worker as it is, which is a big problem.

  In relation to this, Patent Document 2 discloses a fall prevention device intended for a lighting fixture or the like, but having a configuration for absorbing an impact when dropped. In the device of Patent Document 2, a drum that winds a belt (corresponding to a lifeline) is rotatably accommodated in a case, and a ratchet wheel (ratchet gear) is attached to the case, while a lock claw (ratchet). Nail) is provided on the drum. And when the lighting fixtures fall and the belt (corresponding to the lifeline) is pulled out rapidly and the drum rotates at a high speed, the lock claw engages with the ratchet wheel, and the rotation of the drum is locked. Yes. Also, the brake shoe is pressed against the ratchet wheel to give rotational resistance. In addition, when the drum is locked by the engagement of the lock claw and the ratchet wheel as described above, when a load (torque in the belt pulling direction) exceeding a certain value is applied to the drum, the ratchet wheel Rotates gently, and the drum gradually feeds out the belt. Thereby, the impact which acts on a lighting fixture etc. is relieved.

Japanese Utility Model Publication No.7-1951 Utility Model Registration No. 3033362

  In Patent Document 2, a rotation resistance is applied to the ratchet wheel by pressing a brake shoe, and the ratchet wheel rotates only when a load (torque) greater than a certain value is applied. In this case, it is necessary to adjust the load (rotational resistance) when the ratchet wheel starts to rotate by tightening the brake shoe, but there is a problem that it is very difficult to correctly adjust to a predetermined value determined by design. As a result of adjustment, if the rotational resistance actually applied to the ratchet wheel is too small, the drum rotates at a considerably high speed with the lock claw and the ratchet wheel engaged, and there is a possibility that the crash cannot be prevented. . On the other hand, if the rotational resistance is too large, the drum may not rotate even if a large impact load is applied when the lock claw and the ratchet wheel are engaged. In this case, the impact load is not applied because the belt is not fed out at all. Can not be absorbed.

  An object of the present invention is to provide a fall prevention device capable of imparting a desired rotational resistance to a drum without special adjustment and capable of reliably carrying out fall prevention and shock absorption.

Means for Solving the Problems and Effects of the Invention

  A fall prevention device according to a first aspect of the present invention is a main body case, a main body frame enclosed in the main body case, a winding shaft fixed to the main body frame, and accommodated in the main body case. A drum rotatably attached to a shaft, a lifeline wound around the drum in a state of being fixed to the drum at one end, and drawn out from a drawer opening formed in the body case; and Winding attachment biasing means for biasing in the winding direction, a ratchet wheel having a plurality of ratchet teeth, connected to the drum and rotatably attached to the drum, and the main body case The ratchet wheel engages with the ratchet teeth of the ratchet wheel when the drum rotates in the direction of pulling out the lifeline at a predetermined speed or higher. A lock claw that locks the rotation of the ratchet wheel, and a shock absorbing member is interposed between the drum and the ratchet wheel at the connecting portion, and the shock absorbing member is in a locked state of the ratchet wheel by the lock claw In the method, when a torque in the pulling direction of the lifeline acts on the drum, a rotational resistance is applied to the drum while allowing the drum to rotate with respect to the ratchet wheel.

  In the fall prevention device of the present invention, when the operator falls and the lifeline is rapidly pulled out from the drum, the rotation of the ratchet wheel is locked by the lock claw, the rotation of the drum is stopped, and the lifeline is stopped from being pulled out. , The fall of workers is prevented. Furthermore, when the torque in the pulling direction of the lifeline acts on the drum due to the impact load when the ratchet wheel is locked, the drum tries to rotate with respect to the ratchet wheel. A rotational resistance is imparted to the drum by the impact absorbing member. As a result, the drum rotates at a slow speed and the lifeline is gradually pulled out, so that the impact at the time of dropping is absorbed.

  Here, the rotational resistance applied to the drum is determined by the shape and material of the shock absorbing member. Therefore, in order to provide a desired rotational resistance, it is only necessary to incorporate an impact absorbing member manufactured by determining conditions such as shape and material, and no special adjustment work is required. Therefore, the rotation resistance applied to the drum by adjustment does not vary, and the fall prevention and the shock absorption can be reliably performed.

  A fall prevention device according to a second aspect of the present invention is characterized in that, in the first aspect of the invention, the impact absorbing member is deformed to absorb a drop impact.

  According to the present invention, when an operator crashes, when the ratchet wheel is locked, a torque is applied to the drum in the pulling direction of the lifeline by an impact load, and the drum tries to rotate with respect to the ratchet wheel. When the shock absorbing member inserted between the two is deformed, rotational resistance is imparted to the drum. Thereby, the drop impact is absorbed. In this case, the rotational resistance applied to the drum is determined by the difficulty of deformation of the shock absorbing member (bending rigidity or torsional rigidity).

  The fall prevention device according to a third aspect of the invention is the first or second aspect of the invention, wherein when the ratchet wheel is locked by the lock claw and the torque in the pulling direction of the lifeline acts on the drum, The drum approaches the axial direction while rotating with respect to the ratchet wheel, and the impact absorbing member is compressed and crushed.

  According to the present invention, since the drum and the ratchet wheel are screwed together via the threaded portion, the torque in the pulling direction of the lifeline is applied to the drum by the impact load while the ratchet wheel is locked. Sometimes the drum approaches as it rotates relative to the ratchet wheel. At this time, the impact absorbing member inserted between the drum and the ratchet wheel is compressed and crushed, thereby imparting rotational resistance to the drum. In this case, the rotational resistance applied to the drum is determined by the difficulty of crushing the impact absorbing member.

  According to a fourth aspect of the present invention, there is provided the fall prevention device according to the third aspect, wherein when the drum approaches the ratchet wheel and the shock absorbing member is crushed by a predetermined amount, the further approach of the drum is restricted. It has the stopper to do.

  In the present invention, when the shock absorbing member is crushed to some extent, the approach of the drum to the ratchet wheel is restricted by the stopper and the drum does not rotate. Therefore, the lifeline is pulled out more than a certain amount after locking by the lock claw. Can be prevented.

  According to a fifth aspect of the present invention, there is provided the fall prevention device according to any one of the third and fourth aspects, wherein the first shock absorbing member and the second shock absorbing member are interposed between the drum and the ratchet wheel. The second shock absorbing member is inserted with a larger gap in the axial direction between the drum and the ratchet wheel than the first shock absorbing member. It is what.

  In the present invention, the “gap” in the axial direction between the shock absorbing member and the drum and the ratchet wheel is the width of the space where no other member is interposed between the shock absorbing member and the drum or the ratchet wheel. Point to. In the present invention, since the axial clearance between the drum and the ratchet wheel of the second shock absorbing member is larger than that of the first shock absorbing member, the first shock absorbing member is firstly used. After the member is crushed by a predetermined amount (by the gap), the second shock absorbing member is compressed and begins to be crushed, and the rotational resistance applied to the drum increases. Therefore, even when the first shock absorbing member alone does not sufficiently absorb the shock, the life shock can be prevented from being pulled out more than a certain amount while the remaining shock is absorbed by the second shock absorbing member.

  A fall prevention device according to a sixth aspect of the present invention is the invention according to any one of the third to fifth aspects, wherein the impact absorbing member is formed in a cylindrical shape, and is annular on at least one of an inner surface or an outer surface of the cylindrical impact absorbing member. A groove is formed.

  The portion where the annular groove of the cylindrical shock absorbing member is formed has a locally weak strength, and when the shock absorbing member is compressed, plastic deformation (bending) is first generated in the annular groove portion. . That is, since the position where the deformation is generated is determined, it can be always crushed in the same deformation mode, and the rotational resistance applied to the drum is unlikely to vary.

  According to a seventh aspect of the present invention, there is provided the fall preventing device according to the sixth aspect, wherein one annular inner surface groove is formed on the inner surface of the axially central portion of the shock absorbing member, and the axially opposite end portions of the shock absorbing member are formed. Two annular outer surface grooves are formed on the outer surface so as to sandwich the inner surface groove in the axial direction.

  Once the impact-absorbing member is compressed and plastic deformation occurs, the strength of the impact-absorbing member is suddenly reduced, so that the rotational resistance applied to the drum is also abruptly reduced and the impact-absorbing effect is drastically reduced. In the present invention, one inner surface groove is formed on the inner surface of the axial central portion of the cylindrical impact absorbing member, while two outer surface grooves are formed at both ends so as to sandwich the inner surface groove in the axial direction. It is formed. When the shock absorbing member is compressed in the axial direction, deformation occurs in each of the three grooves, and the cylindrical shock absorbing member has a shape bulging outward in the radial direction. Since such a shape develops strength against compression, the strength can be maintained for a certain time against compression after plastic deformation (bending) occurs in the grooved portion, A constant rotational resistance can be continuously applied.

  The fall prevention device according to an eighth aspect of the present invention is the invention according to any one of the third to seventh aspects, wherein the winding shaft is provided with axial movement of the ratchet wheel when the shock absorbing member is crushed. It is characterized in that a restricting part for restricting is provided.

  When the impact absorbing member that exists between the drum and the ratchet wheel is crushed, the ratchet wheel is loosened by that amount, and the position of the lock claw provided on the main body case side shifts and disengages. There is a risk that. In the present invention, since the restricting portion that restricts the movement of the ratchet wheel in the axial direction is provided on the winding shaft, it is possible to prevent the ratchet wheel from rattling and disengaging from the lock pawl.

It is a figure which shows the usage example of the fall prevention instrument which concerns on this invention. It is a disassembled perspective view of a fall prevention instrument. It is a front view of the fall prevention instrument of the state which removed the one side of the main body case. It is a side view of a fall prevention device. It is sectional drawing of the internal structure except the main body case of the fall prevention tool shown by FIG. FIG. 6 is a detailed view of a part A in FIG. 5, (a) shows a state before shock absorption, and (b) shows a state after shock absorption. It is sectional drawing of the impact-absorbing member which concerns on a change form. It is sectional drawing of the impact-absorbing member which concerns on another modification. It is sectional drawing equivalent to FIG. 6 of the fall prevention instrument which concerns on another modification. It is sectional drawing equivalent to FIG. 6 of the fall prevention instrument which concerns on another modification. It is a side view equivalent to FIG. 4 of the fall prevention instrument which concerns on another modification. It is a graph of a drop test result.

  Next, an embodiment of the present invention will be described. FIG. 1 is a diagram showing a usage example of the fall prevention device according to the present invention. As shown in FIG. 1, the fall prevention device 1 is hung from a structure on a construction site and suspended from above. Further, the fall prevention device 1 has a drum 4 (see FIGS. 2 and 5) for winding the lifeline 5 inside the main body case 2, and a hook 10 attached to the tip of the lifeline 5 drawn from the drum 4. Is fixed to a safety belt 11 attached to the waist of the operator. In this state, the worker performs work at a high place, and the lifeline 5 is pulled out of the main body case 2 or wound into the main body case 2 in accordance with the movement of the worker on the gantry 100. In the unlikely event that an operator steps off from the gantry 100 and falls, the lifeline 5 is quickly pulled out from the main body case 2, but immediately the rotation of the drum 4 is locked and the withdrawal of the lifeline 5 stops. This prevents workers from crashing.

  Next, the structure of the fall prevention device 1 will be described in detail. FIG. 2 is an exploded perspective view of the fall prevention device 1. 3 is a front view of the fall prevention device 1 with one side of the main body case 2 (case divided body 12 shown in FIG. 2) removed, and FIG. 4 is a side view of the fall prevention device 1. However, in FIG. 4, the main body case 2 is shown in cross section so that the structure inside the main body case 2 can be understood. 5 is a cross-sectional view of the internal structure of the fall prevention device 1 excluding the main body case 2 shown in FIG.

  As shown in FIGS. 2 to 5, the fall prevention device 1 includes a main body case 2, brackets 17 and 18 (corresponding to the main body frame of the present application), a winding shaft 3, a drum 4, and a wire rope. The lifeline 5, the mainspring 6, the ratchet wheel 7, and the lock claw 8 are provided.

  As shown in FIG. 2, the main body case 2 has a structure in which two case divided bodies 12 and 13 are coupled by a plurality of bolts. Hole portions 12a and 13a are formed in the upper portions of the case divided bodies 12 and 13, respectively, and a belt 15 for suspension is attached to the hole portions 12a and 13a via a connector 14, as shown in FIG. An opening forming member 16 is attached to the lower part of the main body case 2, and a drawer port 16 a for the lifeline 5 is formed by the opening forming member 16. Brackets 17 and 18 are respectively fixed to the two case division bodies 12 and 13 of the main body case 2, and both ends of the winding shaft 3 are fixed to these two brackets 17 and 18. That is, the winding shaft 3 is fixed to brackets 17 and 18 included in the main body case 2. Similar to the main body case 2, hanging holes 17 a and 18 a are formed on the upper portions of the two brackets 17 and 18, respectively.

  As shown in FIGS. 4 and 5, two flanges 20 and 21 are fixed to both ends in the width direction of the drum 4. Further, as shown in FIG. 5, a hollow cylinder 22 having a flange 22 a is fixed to the center of the drum 4, and the winding shaft 3 is inserted into the hollow cylinder 22, whereby the drum 4 and the hollow cylinder 22 are inserted. And can be rotated around the winding shaft 3. As shown in FIGS. 2 and 5, a threaded portion 22 b is formed on the outer peripheral surface of the distal end side portion of the hollow tube 22 with respect to the flange portion 22 a. One end of the lifeline 5 is fixed to the drum 4, and the lifeline 5 is wound between the two flanges 20 and 21 by rotating the drum 4. Further, the lifeline 5 is drawn out from the drum 4 by the drum 4 rotating in the direction opposite to the winding direction, and is drawn out from the drawer port 16 a of the main body case 2.

  A mainspring case 23 is fixed to one flange 21 of the drum 4 and can rotate integrally with the drum 4. The mainspring case 23 accommodates a mainspring 6 (winding urging means) made of various spring steels. The mainspring 6 has one end fixed to the mainspring case 23 and the other end fixed to the winding shaft 3, and urges the mainspring case 23 (drum 4) in the winding direction of the lifeline 5.

  The other flange 20 of the drum 4 is provided with a ratchet wheel 7 having a plurality of ratchet teeth 7a on the outer peripheral portion. The ratchet wheel 7 is fixed by a nut 24 and a joint plate 25 disposed on the inner side of the ratchet wheel 7, and the nut 24 is screwed with a screw portion 22 b of the hollow cylinder 22. That is, the drum 4 and the ratchet wheel 7 are screwed together by the hollow cylinder 22 and the nut 24 and can rotate integrally. Two cylindrical impact absorbing members 26 and 27 are mounted on the outer surface of the hollow cylinder 22, which is a connecting part between the drum 4 and the ratchet wheel 7, between the flange 22 a and the nut 24. . These two shock absorbing members 26 and 27 will be described later.

  As shown in FIGS. 3 to 5, the lock claw 8 is attached to the bracket 17 so as to be rotatable about a rotation shaft 28. As can be seen from FIG. 3, the lock claw 8 has claw portions 8 a and 8 b at both ends sandwiching the rotation shaft 28, and the lock claw 8 has a spring in a direction in which one claw portion 8 a contacts the ratchet wheel 7. 29 is urged to rotate. The one claw portion 8a is in contact with the outer peripheral surface of the ratchet wheel 7, and the ratchet wheel 7 is in the winding direction of the lifeline 5 (in the direction of arrow A in FIG. 3) and in the pulling out direction (in the direction of arrow B). In any case, the shape does not engage with the ratchet teeth 7a. On the other hand, when the ratchet wheel 7 rotates in the pulling direction of the lifeline 5 (arrow B direction) while the other claw portion 8b is in contact with the outer peripheral surface of the ratchet wheel 7, it has a shape that engages with the ratchet teeth 7a. ing.

  When the lifeline 5 is pulled out at a relatively slow speed and the rotational speed of the drum 4 is less than a predetermined speed, one claw portion 8a of the lock claw 8 is pressed against the ratchet wheel 7 by the biasing force of the spring 29. In this state, the ratchet wheel 7 rotates together with the drum 4 in the pulling direction (arrow B direction). At this time, the other claw portion 8b is separated from the ratchet wheel 7, and the rotation of the ratchet wheel 7 is not locked. On the other hand, when the operator crashes, the lifeline 5 is pulled out at a very high speed, and when the rotational speed in the pulling-out direction of the drum 4 exceeds a predetermined speed, the ratchet teeth 7a of the ratchet wheel 7 that rotates at a high speed. As a result, the one claw portion 8a is kicked up, and the other claw portion 8b overcomes the urging force of the spring 29 and comes into contact with the ratchet wheel 7 by the reaction. At this time, the other claw portion 8b is engaged with the ratchet teeth 7a, the rotation of the ratchet wheel 7 (drum 4) is instantaneously locked, and the withdrawal of the lifeline 5 is stopped.

  Next, the shock absorbing members 26 and 27 will be described. The shock absorbing members 26 and 27 are members for absorbing an impact load generated when an operator crashes and the rotation of the ratchet wheel 7 is locked, and is provided between the drum 4 and the ratchet wheel 7. It has been.

  6A and 6B are detailed views of a portion A in FIG. 5, in which FIG. 6A shows a state before shock absorption, and FIG. 6B shows a state after shock absorption. As shown in FIG. 6, two cylindrical impact absorbing members (first impact absorbing members) are provided between the flange portion 22 a of the hollow cylinder 22 fixed to the drum 4 and the nut 24 fixed to the ratchet wheel 7. 26, a second shock absorbing member 27) is inserted. Here, as described above, since the drum 4 and the ratchet wheel 7 are connected by screwing the hollow cylinder 22 and the nut 24, the rotation of the ratchet wheel 7 is locked by the lock claw 8 when the operator falls. After that, when a torque acts on the drum 4 in a direction in which the lifeline 5 is further pulled out by an impact load, the drum 4 rotates with respect to the ratchet wheel 7 and the ratchet wheel 7 along the winding shaft 3 (FIG. 6B). In the direction indicated by arrow R). At this time, the drum 4 approaches the ratchet wheel 7 while compressing and crushing the impact absorbing members 26 and 27 inserted between the drum 4 and the ratchet wheel 7, and rotational resistance is imparted to the drum 4. .

  Here, the rotational resistance applied to the drum 4 is determined by the resistance to crushing of the impact absorbing members 26 and 27 determined by the shape and material of the impact absorbing members 26 and 27. Therefore, in order to give the drum 4 a desired rotational resistance, it is only necessary to determine the shape and material of the shock absorbing members 26 and 27 and then incorporate these shock absorbing members 26 and 27. No special adjustment is required to give the drum 4 a desired rotational resistance.

  Further, the detailed configuration of the shock absorbing members 26 and 27 will be described. As shown in FIG. 6, of the two shock absorbing members 26 and 27, the first shock absorbing member 26 has a single annular inner groove 26 a formed on the inner surface of the central portion in the axial direction and the axial direction. Two annular outer surface grooves 26b are formed on the outer surfaces of both ends so as to sandwich the inner surface groove 26a in the axial direction. On the other hand, a flange portion 27 a is formed at one end portion of the second shock absorbing member 27.

  Then, as shown in FIG. 6A, the second shock absorbing member 27 is mounted on the outer peripheral surface of the hollow cylinder 22 in a state where the flange part 27a is in contact with the flange part 22a of the hollow cylinder 22, The first shock absorbing member 26 is mounted so as to cover the second shock absorbing member 27. The first shock absorbing member 26 has both end surfaces in contact with other members (the flange portion 27a of the second shock absorbing member 27 and the nut 24), whereas the second shock absorbing member 26 A predetermined gap d exists between the end surface of the 27 opposite to the flange portion 27 a and the nut 24. That is, the second shock absorbing member 27 is disposed with a large gap in the axial direction between the second shock absorbing member 27 and the ratchet wheel 7 (nut 24), as compared with the first shock absorbing member 26.

  When the torque in the pulling direction of the lifeline 5 acts on the drum 4 while the ratchet wheel 7 is locked by the lock claw 8, the first impact absorbing member 26 is compressed first while the drum 4 approaches the ratchet wheel 7. It is crushed. Here, the first impact absorbing member 26 is crushed by being first plastically deformed (bent) in a weak portion where one inner surface groove 26a and two outer surface grooves 26b are formed. That is, since the position where the deformation is generated is determined by the annular grooves 26a and 26b, it can be always crushed in the same deformation mode, and the rotational resistance applied to the drum 4 is unlikely to vary.

  In addition, once plastic deformation occurs in the impact absorbing member, the strength of the impact absorbing member is suddenly reduced, so that the rotational resistance applied to the drum 4 is also rapidly reduced, and the impact absorbing effect is drastically reduced. However, the first shock absorbing member 26 of the present embodiment is formed with a single inner groove 26a in the center and two outer grooves 26b so as to sandwich the inner groove 26a. When the shaft is compressed in the axial direction, deformation (bending) occurs in the three grooves 26a and 26b, respectively, so that the first shock absorbing member 26 swells radially outward as shown in FIG. 6B. It becomes a shape. Since such a shape develops strength against compression, the strength can be maintained for a certain period of time against compression after plastic deformation (bending) occurs in the portions where the grooves 26a and 26b are formed. The drum 4 can be continuously imparted with a certain rotational resistance.

  Further, when the first shock absorbing member 26 is compressed and crushed by the gap d shown in FIG. 6A, both axial ends of the second shock absorbing member 27 are in contact with the flange portion 22a of the hollow cylinder 22 and the nut 24. It becomes a state and begins to be compressed. That is, after the first shock absorbing member 26 is crushed by a certain amount, the second shock absorbing member 27 is compressed and begins to be crushed, so that the rotational resistance applied to the drum 4 is increased. Even when the shock absorption is not sufficiently performed by the member 26 alone, it is possible to prevent the lifeline 5 from being pulled out more than a certain amount while absorbing the remaining shock by the second shock absorbing member 27.

  The first shock absorbing member 26 to be compressed first needs to start crushing immediately after locking so that a large shock load immediately after the ratchet wheel 7 is locked can be quickly absorbed. It is preferably formed of a material having a relatively low strength (for example, an aluminum alloy such as duralumin). In addition to forming the annular grooves 26a and 26b as described above, it is preferable to reduce the thickness to some extent. On the other hand, the second shock absorbing member 27 to be compressed later absorbs (attenuates) the shock load that could not be absorbed by the first shock absorbing member 26 after the first shock absorbing member 26 absorbed the shock to some extent. However, since the function of suppressing the withdrawal of the lifeline 5 is required, it is stronger than the first shock absorbing member 26 so that it can be prevented from being crushed and a larger rotational resistance can be applied to the drum 4. It is preferably formed of a high material (for example, carbon steel, stainless steel, etc.), and a material having a slightly thicker wall is preferable.

  By the way, as described above, when the impact absorbing members 26 and 27 existing between the drum 4 and the ratchet wheel 7 are crushed, an axial backlash occurs in the ratchet wheel 7 to the main body case 2 side. There is a possibility that the position of the lock claw 8 provided is shifted and the engagement is disengaged. Therefore, in this embodiment, the winding shaft 3 is provided with a configuration for restricting the movement of the ratchet wheel 7 in the axial direction.

  Specifically, as shown in FIG. 6, a stepped portion 3 a is formed at one end portion (the right end portion in FIG. 4) of the winding shaft 3. A joint plate 25 for fixing the ratchet wheel 7 and the nut 24 is attached to the small diameter portion of the tip of the winding shaft 3 on the right side of the stepped portion 3a, and the left surface of the joint plate 25 is the stepped portion 3a. The movement of the ratchet wheel 7 to the left side in the figure is restricted by contacting the wheel. That is, since the stepped portion 3a formed on the winding shaft 3 functions as a restricting portion that restricts the movement of the ratchet wheel 7 in the axial direction (leftward), the ratchet wheel 7 rattles and the locking claw 8 and Is disengaged.

  The restricting portion is not limited to the stepped portion 3a. Instead of the stepped portion 3a, the winding shaft 3 is provided with a protrusion protruding radially outward, and this protrusion is the ratchet wheel 7 (nut 24). Alternatively, a configuration may be adopted in which the movement in the axial direction (left side) is restricted by engaging from the left side in the figure.

  Next, operation | movement of the fall prevention instrument 1 of this embodiment is demonstrated. As shown in FIG. 1, while the worker is working on the gantry 100, the lifeline 5 is pulled out from the drum 4 in the main body case 2, or the lifeline 5 is wound around the drum 4. At this time, since the lifeline 5 is pulled out at a relatively slow speed, the lock claw 8 is not kicked up by the ratchet teeth 7a, and the claw portion 8b does not engage with the ratchet teeth 7a. Is not locked.

  On the other hand, when the worker falls from the gantry 100, the lifeline 5 is pulled out from the main body case 2 at a very high speed, so that the ratchet wheel 7 rotates at a high speed integrally with the drum 4 and is thereby moved by the ratchet teeth 7 a. One claw portion 8a of the lock claw 8 is kicked up. Thereby, the other nail | claw part 8b of the lock nail | claw 8 engages with the ratchet tooth | gear 7a, and rotation of the ratchet wheel 7 is locked.

  When the rotation of the ratchet wheel 7 is locked, the rotation of the drum 4 is also stopped and the pulling out of the lifeline 5 is stopped, so that an impact load acts on the operator who has fallen. However, in the present embodiment, the drum 4 rotates in the pulling direction of the lifeline 5 while compressing and crushing the first shock absorbing member 26 interposed between the drum 4 and the ratchet wheel 7 while being compressed. Rotational resistance is applied to the drum 4 and the lifeline 5 is gradually pulled out, and the impact is absorbed. Further, when the first shock absorbing member 26 is crushed by a predetermined amount, the second shock absorbing member 27 starts to be compressed and a larger rotational resistance is applied to the drum 4, while absorbing the remaining shock load, It is prevented that the lifeline 5 is pulled out too much.

  In the fall prevention device 1 of the present embodiment, the take-up shaft 3 is fixed to the main body case 2, and the drum 4 and the ratchet wheel 7 can be rotated with respect to the fixed take-up shaft 3. Yes. On the other hand, the winding shaft 3 is rotatably supported with respect to the main body case 2, and the drum 4 and the ratchet wheel 7 are fixed to the winding shaft 3 (the winding shaft 3 and the drum 4). And a configuration in which the ratchet wheel 7 rotates integrally). However, this embodiment is used for preventing a worker who performs work at a high place from falling, and the lifeline 5 is, for example, a fairly long one that extends to several tens of meters. Therefore, when adopting a configuration in which the winding shaft 3 is rotatably supported as described above, in order to stably support the heavy winding shaft 3 around which the lifeline 5 is wound, The structure becomes large and complicated, for example, the bearings at both ends of the shaft 3 become large. Therefore, in the present embodiment, the take-up shaft 3 is fixed to the brackets 17 and 18, and the drum 4 and the ratchet wheel 7 can be rotated on the take-up shaft 3, whereby the take-up shaft 3 is taken up by the drum 4. Even if the length of the lifeline 5 is long, the structure of the instrument can be simplified.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

1] The shape and arrangement of the shock absorbing member can be changed as appropriate. For example, as shown in FIG. 7A, only the annular inner groove 26a may be formed in the shock absorbing member 26. As shown in FIG. 7A, if one inner surface groove 26a is formed in the axial central portion of the shock absorbing member 26, the radial direction when compressed in the axial direction as in the above embodiment. Since it deform | transforms so that it may bulge outside, strength can be expressed. Moreover, as shown in FIG.7 (b), only the outer surface groove | channel 26b may be formed. In addition, the number of the inner surface grooves 26a or the number of the outer surface grooves 26b can be changed as appropriate. Further, as shown in FIG. 7C, the inner surface groove 26a and the outer surface groove 26b may be formed at the same position in the axial direction, and the shock absorbing member 26 may be formed in a bellows shape. Further, as shown in FIGS. 8A to 8D, the inner surface groove 26a or the outer surface groove 26b may be a groove having an arcuate cross section. Or as shown in FIG.8 (e), the groove | channel may not be formed in both an inner surface and an outer surface.

  In the above embodiment, the second shock absorbing member 27 has one end abutting against the drum 4 (hollow cylinder 22), and there is a gap between the other end and the ratchet wheel 7 (nut 24) ( On the contrary, there may be a gap between the ratchet wheel 7 (nut 24) and the drum 4 (hollow cylinder 22).

  The impact absorbing member is not necessarily cylindrical, and a plurality of impact absorbing members may be arranged around the hollow cylinder 22 in the circumferential direction.

2] In the above-described embodiment, the two types of shock absorbing members 26 and 27 are provided. However, if only the first shock absorbing member 26 can sufficiently absorb the shock load, the second shock absorbing member 27 is omitted. May be.

  Alternatively, instead of providing a plurality of types of impact absorbing members, a stopper that restricts further approach of the drum when the impact absorbing member is crushed by a predetermined amount may be provided. For example, in the above-described embodiment, instead of the cylindrical second shock absorbing member 27, a cylindrical stopper with higher strength (high rigidity) that does not collapse even when compressed between the drum 4 and the ratchet wheel 7 is provided. May be. Further, the stopper does not need to be interposed between the drum 4 and the ratchet wheel 7 unlike the second shock absorbing member 27, and is fixed to other members such as the main body case 2 and the brackets 17 and 18, for example. Then, when the drum 4 approaches the ratchet wheel 7, the drum 4 may be installed at a predetermined position where it hits the drum 4 to prevent further approach. Since the stopper is provided in this manner, when the shock absorbing member is crushed to some extent, the further approach of the drum 4 to the ratchet wheel 7 is restricted by the stopper and the drum 4 does not rotate. It can prevent that an absorption member continues being crushed and a lifeline is pulled out more than fixed.

3] The shock absorbing member 26 inserted between the drum 4 and the ratchet wheel 7 in the above-described embodiment is crushed when the drum 4 approaches the ratchet wheel 7, thereby causing the drum 4 to have rotational resistance. However, it is also possible to adopt a configuration other than the above configuration.

  For example, it is possible to absorb the impact by the screw mechanism itself including the screw portion 22 b of the hollow cylinder 22 and the nut 24, which connects the drum 4 and the ratchet wheel 7. That is, as shown in FIG. 9, the screw portion 22b, which is a male screw, or the female screw hole of the nut 24 may be configured to have a tapered shape. A configuration in which 24 female screw holes are tapered is disclosed). In this case, as the drum 4 approaches the ratchet wheel 7 from the state of FIG. 9A and the screw portion 22b is screwed into the female screw hole of the nut 24 as shown in FIG. 4 is gradually given rotational resistance. In this embodiment, the screw portion 22b and the nut 24 correspond to the shock absorbing member of the present application, and the rotational resistance applied to the drum 4 is determined by the taper angle of the female screw hole of the screw portion 22b or the nut 24.

  In addition, as shown in FIG. 10, the drum 4 and the ratchet wheel 7 may be coupled by an impact absorbing member 30 that can be torsionally deformed, instead of being threadably coupled by a threaded portion. In this case, when the drum 4 is rotated with respect to the ratchet wheel 7 due to an impact load, the impact absorbing member 30 is twisted to give a rotational resistance to the drum 4. In this case, the rotational resistance applied to the drum 4 is determined by the torsional rigidity of the shock absorbing member 30.

4] In the above embodiment, the ratchet wheel 7 connected to the drum 4 so as to rotate integrally is locked by the lock claw 8 provided on the bracket 17 (main body frame) side (FIGS. 3A and 3B). 4), conversely, the lock claw 8 can be integrated with the drum 4 provided on the drum 4 side, while the ratchet wheel 7 is fixed to the bracket 17 side. . An example is given below.

  As shown in FIG. 11, the ratchet wheel 37 has ratchet teeth 37 a on the inner peripheral side, and the ratchet wheel 37 is fixed to the bracket 17. On the other hand, the lock claw 38 is disposed on the inner side of the ratchet wheel 37 so as to be engageable with the ratchet teeth 37 a of the ratchet wheel 37. The lock claw 38 is attached to a base plate 31 that is rotatable with respect to the take-up shaft 3, and the base plate 31 is screwed and connected to a screw portion (not shown) on the drum 4 side by a nut 32. Thus, the lock claw 38 can rotate integrally with the drum 4 in a state where it is not engaged with the ratchet wheel 37. Similarly to the above-described embodiment, the lock claw 38 engages with the ratchet teeth 37a of the ratchet wheel 37 when the rotational speed of the drum 4 exceeds a predetermined speed. Here, as in the above-described embodiment, when the rotation speed of the drum 4 is increased, the lock pawl 38 is engaged with the ratchet teeth 37a when the other end is strongly kicked up. (Refer FIG. 3) may be sufficient, but the thing of the structure engaged with the ratchet tooth | gear 37a by displacing outside by a centrifugal force may be sufficient.

  In this configuration, a shock absorbing member (for example, the shock absorbing member 26 of the above-described embodiment) is provided between the connecting portion between the drum 4 and the lock claw 38, that is, the screw portion on the drum 4 side and the nut 32 on the lock claw 38 side. , 27 (see FIG. 6), or the tapered screw mechanism (see FIG. 9) of the modified form described above is inserted. When the lock claw 38 is engaged with the ratchet wheel 37 and the rotation of the drum 4 is locked, when the torque is applied to the drum 4 in the pulling direction of the lifeline 5 due to the impact load, the drum 4 is moved to the lock claw 38 ( While rotating toward the base plate 31), rotation resistance is applied to the drum 4 by the impact absorbing member between the drum 4 and the lock claw 38.

5] The lifeline 5 is not limited to a wire rope, and a long body (for example, a belt) other than the wire rope may be employed.

(Verification of impact absorption effect)
Next, it verified by experiment about the impact absorption effect of the fall prevention instrument provided with the impact-absorbing member of this invention. Here, the verification was performed using an impact absorbing member 26 having one arcuate inner groove 26a at the center and two arcuate outer grooves 26b on both sides thereof as shown in FIG. 8 (d). Then, a drop test was performed with a weight of 120 kg in accordance with the test conditions defined by the “Safety Belt Structure Guidelines” (TR-No. 35) issued by the National Institute for Occupational Safety and Health. The result is shown in FIG.

  With the safety belt structure guideline, when a drop test is performed using a drop body (weight) having a mass of 85 kg, the drop body can be held, the maximum impact load does not exceed 8.0 kN, and the drop distance is 2 It is required not to exceed 0.0m. On the other hand, as shown in FIG. 12, in this test, the maximum impact load was about 4 kN, and the fall distance was 1.1 m. In other words, even in tests under stricter conditions than the test set by the safety belt structure guideline (weight of this test: 120 kg> falling body set by the guideline: 85 kg), the values required by the safety belt structure guideline are satisfied. From this, it is understood that the fall prevention device of the present invention has a very high impact absorbing effect.

DESCRIPTION OF SYMBOLS 1 Fall prevention device 2 Main body case 3 Winding shaft 3a Stepped part 4 Drum 5 Lifeline 6 Spring spring 7 Ratchet wheel 7a Ratchet tooth 8 Lock claw 16a Drawer port 17, 18 Bracket part 22b Screw part 24 Nut 26 1st shock absorption member 26a Inner surface Groove 26b outer surface groove 27 second shock absorbing member 30 shock absorbing member 37 ratchet wheel 38 lock claw

Claims (8)

A body case,
A main body frame enclosed in the main body case;
A winding shaft fixed to the body frame;
A drum housed in the body case and rotatably attached to the winding shaft;
A lifeline that is wound around the drum in a state of being fixed to the drum at one end and drawn out from a drawer port formed in the main body case,
Winding attachment biasing means for biasing the drum in the winding direction of the lifeline;
A ratchet wheel having a plurality of ratchet teeth, connected to the drum and attached to the take-up shaft so as to rotate integrally with the drum;
A locking claw that is provided on the main body frame and engages with the ratchet teeth of the ratchet wheel and locks the rotation of the ratchet wheel when the drum rotates in the direction of pulling out the lifeline at a predetermined speed or higher;
In the connecting portion between the drum and the ratchet wheel, an impact absorbing member is inserted between the two,
The shock absorbing member allows the drum to rotate with respect to the ratchet wheel when torque in the pulling direction of the lifeline is applied to the drum in a locked state of the ratchet wheel by the lock claw. A fall prevention device, characterized by imparting rotational resistance to the body.   The fall prevention device according to claim 1, wherein the impact absorbing member is deformed to absorb a drop impact. The drum and the ratchet wheel are screwed together via a screw part,
In the locked state of the ratchet wheel by the lock claw, when the torque in the pulling direction of the lifeline acts on the drum, the drum approaches the axial direction while rotating with respect to the ratchet wheel, and the impact The fall prevention device according to claim 1 or 2, wherein the absorbing member is compressed and crushed.   The fall prevention according to claim 3, further comprising a stopper for restricting further approach of the drum when the drum approaches the ratchet wheel and the shock absorbing member is crushed by a predetermined amount. Instruments. A first shock absorbing member and a second shock absorbing member are inserted between the drum and the ratchet wheel,
The second shock absorbing member is disposed with a larger gap in the axial direction between the drum and the ratchet wheel than the first shock absorbing member. Item 5. The fall prevention device according to Item 3 or 4.   6. The crash according to claim 3, wherein the impact absorbing member is formed in a cylindrical shape, and an annular groove is formed on at least one of an inner surface and an outer surface of the cylindrical impact absorbing member. Stopper device. One annular inner surface groove is formed on the inner surface of the central portion in the axial direction of the shock absorbing member,
The fall prevention device according to claim 6, wherein two annular outer surface grooves are formed on outer surfaces of both end portions in the axial direction of the shock absorbing member so as to sandwich the inner surface groove in the axial direction.   The winding shaft is provided with a restricting portion for restricting movement of the ratchet wheel in the axial direction when the shock absorbing member is crushed. The described fall prevention device.

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