Energy absorption mechanism for ropes

Abstract

To provide an energy absorbing mechanism for a rope capable of exhibiting high impact energy absorbing performance to an impact applied to the rope and adjusting the absorbing performance of the impact energy.SOLUTION: An energy absorbing mechanism 20 for a rope is provided on a guard fence 10 for receiving load impact by using the rope 16, and absorbs impact energy applied to the rope. The energy absorbing mechanism 20 comprises a cylindrical housing 22, a mounting part 26 to be attached to a fixed object fixed to the foundation, and a belt-like rigid member 30 having one end fixed to the housing, folded back in the housing, extended while contacting with an inner surface of the housing, and having the other end extended from an opening of the housing. The other end of the rigid member is connected to the rope with the other end pulled outward from the housing when an impact load is applied to the rope.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an energy absorption mechanism for a rope, and more particularly to an energy absorption mechanism for a rope that absorbs impact energy applied to a rope stretched over a protective fence that captures falling rocks and the like. [Background technology]

[0002] Conventionally, protective fences have been installed on mountain slopes to protect adjacent roads, railways, residences, etc. from natural disasters such as landslides and rockfalls. Protective fences are generally constructed by suspending ropes or nets between multiple posts erected at intervals.

[0003] When a guardrail receives an impact load from a rockfall or the like, the rope or net stretches to absorb the impact energy. To improve the ability to absorb impact energy, a guardrail that uses ropes is equipped with an energy absorption mechanism at the end of the rope, and when a tensile force greater than a predetermined value is applied to the rope, the energy absorption mechanism absorbs the impact energy and reduces the impact load acting on the rope.

[0004] As an example of such an energy absorption mechanism, Patent Document 1 describes a shock absorber that generates frictional resistance between itself and the rope to absorb impact energy. This shock absorber has a main body made of steel plate bent into a U-shape, and with the rope sandwiched between the main body, both ends of the U-shape of the main body are tightened with fastening bolts. The main body is secured to a predetermined installation location using a locking member while gripping the rope. With this shock absorber, when a falling rock hits the rope and a tensile force greater than a predetermined value is applied, the rope slides against the gripping force of the main body, which generates frictional resistance at the contact surface between the rope and the main body, absorbing the impact energy.

[0005] Patent Document 2 also describes an energy absorption mechanism that absorbs impact energy by plastically deforming a portion of a component. This energy absorption mechanism has a steel band-shaped rigid member. This rigid member is wrapped around a cylindrical pin member within a rectangular tubular housing and folded back in a U-shape, with the length from the folded part to one end being shorter than the length to the other end. A stopper member that can abut against the pin member is attached to the end of the rigid member that is farther from the folded part. Both ends of the pin member are fixed to a housing that surrounds the area around which the rigid member is wrapped. The housing is locked to a predetermined installation location using a locking member. A rope is connected to the end of the rigid member that is closer to the folded part (rope connection end).

[0006] In this energy absorption mechanism, when a tensile force equal to or greater than a predetermined value acts on the rope and pulls the rope connection end of the rigid member, plastic deformation occurs in the rigid member, causing the area of ​​the rigid member wound around the pin member to move toward the stopper attachment end of the rigid member. As a result of this plastic deformation, the distance from the folded portion of the rigid member to the rope connection end increases, and the distance to the end where the stopper member is attached decreases. When the stopper member then abuts against the pin member, the plastic deformation of the rigid member stops. The impact energy received by the rope is absorbed by this plastic deformation of the rigid member. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-313828 [Patent Document 2] Patent No. 6906100 Summary of the Invention [Problem to be solved by the invention]

[0008] A structure that absorbs energy by plastically deforming a rigid member, such as the energy absorption mechanism described in Patent Document 2, can achieve higher energy absorption performance than a structure that absorbs energy solely through frictional resistance. However, when a guardrail captures a heavy rockfall at high speed, an impact load of several tons acts on the rope when the rockfall hits, and so sufficient energy absorption performance cannot always be ensured even if the rigid member is plastically deformed. Therefore, there has been a demand for the development of an energy absorption mechanism with higher impact energy absorption performance.

[0009] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide an energy absorption mechanism for a rope that can obtain high impact energy absorption performance against an impact applied to the rope. [Means for solving the problem]

[0010] In order to achieve the above object, the energy absorption mechanism for a rope according to claim 1 comprises: A rope energy absorption mechanism is provided on a safety fence that receives load impacts using a tensioned rope and absorbs impact energy applied to the rope, a cylindrical housing having at least one open end; an attachment portion for attaching the housing to either a fixed object fixed to the ground or a rope; One end is fixed to the housing. ,before a strip-shaped rigid member whose other end extends from the opening of the housing; a rigid member having a folded portion folded back in a U-shape within the housing, the outer surface of the folded extension portion being the portion on the other end side from the folded portion, being installed in a state where it is in contact with the inner wall surface of the housing; and, and The other end of the rigid member is connected to either the fixed object or the rope in a state where the other end is pulled outward from the housing when an impact load is applied to the rope.

[0011] With this configuration, when the safety fence catches a falling rock or the like and an impact load acts on the rope, the folded-back extension portion of the rigid member (the portion of the rigid member from the folded-back portion toward the other end) that is in contact with the inner wall surface of the housing slides along the inner wall surface of the housing and is pulled outward. At this time, the impact energy is absorbed by the frictional resistance between the rigid member and the inner wall surface of the housing. Furthermore, as the other end of the rigid member is pulled, plastic deformation occurs in the rigid member, changing the position of the U-shaped folded-back portion within the housing, and this plastic deformation absorbs the impact energy. In this way, this energy absorption mechanism can absorb impact energy through the frictional resistance and plastic deformation generated in the rigid member, thereby achieving high impact energy absorption performance. Furthermore, compared to conventional systems that plastically deform the rigid member via a fixed pin member, the initial load required for the energy absorption mechanism to operate can be reduced, allowing for smooth and stable absorption of impact energy from the initial operation.

[0012] The invention described in claim 2 is the energy absorption mechanism for a rope described in claim 1, The present invention is characterized by comprising a friction increasing means provided on at least one of the housing and the rigid member for increasing the friction force between the rigid member and the inner wall surface of the housing.

[0013] According to this configuration, the friction increasing means increases the frictional force between the folded extension portion of the rigid member and the inner wall surface of the housing, thereby achieving higher impact energy absorption performance.

[0014] The invention described in claim 3 is the energy absorption mechanism for a rope described in claim 2, The friction increasing means is Inner wall surface of Contact The aforementioned Folded extension part outer surface of The housing Inner wall surface The device is characterized by including a pressing means capable of pressing against the surface and capable of adjusting the pressing force.

[0015] With this configuration, when the safety fence catches a falling rock or the like and an impact load acts on the rope, the folded-back extension portion of the rigid member slides on the inner wall surface of the housing while receiving a pressing force from the pressing means and is pulled outward from the housing. This increases the frictional resistance between the rigid member and the inner wall surface of the housing, improving energy absorption performance. Furthermore, the magnitude of the frictional resistance generated between the rigid member and the inner wall surface of the housing, i.e., the amount of energy absorbed, can be easily changed by adjusting the magnitude of the pressing force from the pressing means.

[0016] The invention described in claim 4 is the energy absorption mechanism for a rope described in claim 3, The pressing means is a friction resistance plate disposed opposite the inner wall surface of the housing with the rigid member interposed therebetween; and a fastening member capable of fastening the friction resistance plate to the housing with a force of any magnitude.

[0017] With this configuration, the folded extension portion of the rigid member is sandwiched between the frictional resistance plate and the inner wall surface of the housing and fastened by the fastening member, and in this state, when the other end of the rigid member is pulled and the energy absorption mechanism is activated, frictional resistance forces are generated between the rigid member and the inner wall surface of the housing and between the rigid member and the frictional resistance plate. The magnitude of the frictional resistance force (the amount of energy absorbed) can be adjusted as appropriate by changing the contact area between the frictional resistance plate and the rigid member, the material of the frictional resistance plate, and the fastening force of the fastening member, thereby widening the adjustment range of energy absorption performance.

[0018] The invention described in claim 5 is the energy absorption mechanism for a rope described in any one of claims 2 to 4, The friction increasing means is opposed to the inner wall surface of the housing of the rigid member. outside the surface and / or the housing of the rigid member The aforementioned The high friction resistance layer is provided on the inner wall surface facing the folded extension portion and has a higher friction resistance than the rigid member and / or the housing.

[0019] According to this configuration, when the other end of the rigid member is pulled outward from the housing, a high friction resistance layer is provided between the folded extension portion of the rigid member and the inner wall surface of the housing, which increases the friction resistance force generated when the rigid member slides on the inner wall surface of the housing, resulting in higher impact energy absorption performance.

[0020] The invention described in claim 6 is the energy absorption mechanism for a rope described in any one of claims 1 to 5, The rigid member is The aforementioned The plate is characterized in that it is formed so that the thickness increases from the folded portion toward the fixed one end.

[0021] According to this configuration, the thickness of the rigid member gradually increases in the region where the rigid member undergoes plastic deformation, so that when the energy absorption mechanism is activated and plastic deformation occurs that changes the position of the folded portion of the rigid member, the amount of energy absorbed by the plastic deformation gradually increases, thereby achieving higher energy absorption performance.

[0022] The invention described in claim 7 is the energy absorption mechanism for a rope described in any one of claims 1 to 6, The housing has an inner wall surface that comes into contact with the rigid member that is inclined so that the area of ​​the closed cross section decreases toward the open one end.

[0023] According to this configuration, when the energy absorption mechanism is activated and plastic deformation occurs that changes the position of the folded portion of the rigid member, the radius of curvature of the folded portion of the rigid member decreases along the inclined inner wall surface of the housing, i.e., the amount of energy absorbed during plastic deformation gradually increases, thereby improving energy absorption performance.

[0024] The invention described in claim 8 is the energy absorption mechanism for a rope described in any one of claims 1 to 7, The rigid member has one end fixed to the housing and The aforementioned In the region between the folded portion and the inner wall surface of the housing, outside The rigid member has a surface having a plurality of notches extending in the width direction of the rigid member.

[0025] With this configuration, when the energy absorption mechanism is activated, plastic deformation occurs in the folded portion of the rigid member, causing it to move toward one end, but because multiple notches are formed on the surface of the area where this plastic deformation occurs, the rigid member can be folded sequentially along the notches into a neat U-shape. This makes it possible to prevent the rigid member from being folded into an unintended shape during plastic deformation, which would otherwise reduce its energy absorption performance.

[0026] The invention described in claim 9 is the energy absorption mechanism for a rope described in any one of claims 1 to 8, The rigid member is provided in the housing. The aforementioned Folded part Inner surface of and when actuated, The aforementioned The housing is characterized by including a pin member that moves toward the opening within the housing while contacting the inner surface of the folded portion.

[0027] According to this configuration, when the energy absorption mechanism is activated and the rigid member undergoes plastic deformation, the rigid member can be bent into a U-shape along the circumferential surface of the pin member, thereby preventing buckling from occurring at the folded portion.

[0028] The invention described in claim 10 is the energy absorption mechanism for a rope described in any one of claims 1 to 9, The rigid member includes at least The aforementioned The present invention is characterized in that it is made up of a plurality of strip plate materials that are stacked separably in the area where the folded portion is formed.

[0029] According to this configuration, by configuring one rigid member with a plurality of strip plate materials, the thickness of one strip plate material can be reduced, making the rigid member more easily deformable. [Effects of the Invention]

[0030] According to the rope energy absorption mechanism of the present invention, when an impact load acts on the rope, the folded-back extended portion of the rigid member in contact with the inner wall surface of the housing slides along the inner wall surface of the housing and is pulled out to the outside of the housing, thereby achieving high impact energy absorption performance due to the accompanying plastic deformation of the rigid member and the frictional resistance force generated between the rigid member and the inner wall surface of the housing. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a schematic diagram showing a safety fence equipped with an energy absorption mechanism for a rope according to the present invention. [Figure 2] FIG. 1 is a perspective view showing a first embodiment of an energy absorption mechanism. [Figure 3] FIG. 2 is a longitudinal cross-sectional view of the energy absorption mechanism taken along the length direction. [Figure 4] FIG. 2 is a cross-sectional view along the length of the energy absorption mechanism. [Figure 5] FIG. [Figure 6] FIG. 5 is a cross-sectional view of the energy absorption mechanism taken along line AA in FIG. 4. [Figure 7A] 10A and 10B are diagrams illustrating the operation of the energy absorption mechanism. [Figure 7B] 10A and 10B are diagrams illustrating the operation of the energy absorption mechanism. [Figure 8] FIG. 10 is a perspective view showing a second embodiment of the energy absorption mechanism. [Figure 9] FIG. 4 is a vertical cross-sectional view showing a second embodiment of the energy absorption mechanism. [Figure 10] FIG. 10 is a vertical cross-sectional view showing a third embodiment of the energy absorption mechanism. [Figure 11] FIG. 10 is a vertical cross-sectional view showing a fourth embodiment of the energy absorption mechanism. [Figure 12A] FIG. 10 is a vertical cross-sectional view showing a fifth embodiment of an energy absorption mechanism. [Figure 12B] FIG. 10 is a perspective view showing a modified example of the rigid member 30. [Figure 13] FIG. 10 is a vertical cross-sectional view showing a sixth embodiment of the energy absorption mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0032] (First embodiment) FIG. 1 is a schematic diagram showing a safety fence 10 equipped with a rope energy absorption mechanism 20 according to the present invention. Note that the drawings used to explain the present invention are schematic diagrams in which the essential components are exaggerated and the dimensions of the components are not precisely depicted. The safety fence 10 is installed on the ground G below a slope and prevents damage by capturing falling rocks, collapsing earth, avalanches, etc. and absorbing impact loads using multiple ropes 16 suspended from multiple support posts 12. The safety fence 10 shown in FIG. 1 includes a column row 11 consisting of multiple support posts 12-1 to 12-4 and multiple ropes 16-1 to 16-9 suspended in multiple stages at predetermined intervals in the vertical direction on the column row 11. The rope energy absorption mechanism 20 absorbs impact energy applied to the rope 16. In this embodiment, an energy absorption mechanism 20 is attached to each rope 16.

[0033] The pillars 12 are embedded in the ground G and erected at predetermined intervals in the horizontal direction (left-right direction) of the mountain slope to form a pillar row 11. Each rope 16 is stretched in a continuous line along the pillar row 11. FIG. 1 shows, as an example, a pillar row 11 consisting of four pillars 12-1 to 12-4. In the following explanation, the two pillars 12-1 and 12-4 located at the extreme ends of the pillar row 11 will be referred to as terminal pillars, and the pillars 12-2 and 12-3 erected between the two terminal pillars 12-1 and 12-4 will be referred to as intermediate pillars.

[0034] Each support 12 is formed in a cylindrical shape and has a plurality of rope holders 13 attached to its outer periphery at intervals in the vertical direction. The holders 13 maintain the vertical spacing of the ropes 16 and can be formed, for example, by welding both ends of a U-shaped metal fitting to the outer periphery of the support 12. By inserting each rope 16 into the inside of each holder 13, the spacing between the multiple ropes 16 can be maintained.

[0035] The outer circumferential surfaces of the intermediate supports 12-2 and 12-3 are provided with locking portions 14 for locking the ends of the ropes 16. The locking portions 14 can be formed, for example, by U-shaped metal fittings with both ends welded to the outer circumferential surfaces of the intermediate supports 12-2 and 12-3.

[0036] Spacing members 18-1 to 18-3 are installed between each support pillar 12 to maintain the vertical spacing of each rope 16. Spacing members 18 are rod-shaped members that are long in the vertical direction (longitudinal direction), and have rope holding holes 18a through which each rope 16 is inserted at predetermined intervals along the length. In the illustrated example, a plurality of U-shaped metal fittings are welded to the outer circumferential surface of the rod-shaped main body at predetermined intervals, and the ropes 16 are inserted into the rope holding holes 18a formed by these U-shaped metal fittings. In the illustrated example, the lower end of spacing member 18 is fixed to the ground G using base 18b, but this is not limited thereto, and the lower end may be spaced apart from the ground G and floating.

[0037] A plurality of ropes 16 are arranged in multiple stages at predetermined intervals in the vertical direction on the column row 11. Each rope 16 is suspended on the slope mountain side of the column row 11, with both ends 16a, 16b folded back from the mountain side to the valley side at the end columns 12-1, 12-4, one end of the rope 16 being anchored to the anchoring portion 14 of the intermediate column 12-2 or 12-3 via the energy absorption mechanism 20, and the other end of the rope 16 being anchored to the anchoring portion 14 of the intermediate column 12-2 or 12-3 without the energy absorption mechanism 20.

[0038] The rope 16 may be a high-strength wire rope formed by twisting together wires made from hard steel wires as specified in JIS G 3506. Wires made from hard steel wires are less susceptible to plastic deformation than wires made from soft steel wires as specified in JIS G 3505, and have high tensile strength and spring properties. The wire diameter of the rope 16 may be, for example, about 10 to 25 mm, preferably 18 mm or more, and the tensile strength of the rope 16 may be, for example, 500 to 2000 N / mm 2 Each rope 30 is suspended from the column row 11 and passed through the holder 13 of the column 12 and the rope holding hole 18a of the spacing member 18, thereby maintaining the vertical spacing.

[0039] Although not shown, the protective fence 10 may also have a structure in which a net is stretched over the rockfall capture surface on which the multiple ropes 16 are suspended. The net may be made of wire mesh, rope, or a combination of these. Wire mesh nets include nets with diamond-shaped or circular mesh, while rope nets include well-known nets such as nets made of ropes crossed in a lattice pattern or nets formed by linking multiple rings. The upper and lower edges of the net can be connected to the uppermost and lowermost ropes 16-1, 16-9 using wires or the like.

[0040] Next, the energy absorption mechanism 20 will be described in detail. FIG. 2 is a perspective view showing a first embodiment of the energy absorption mechanism 20. FIG. 3 is a longitudinal cross-sectional view of the energy absorption mechanism 20 shown in FIG. 2, taken along the longitudinal direction, and FIG. 4 is a transverse cross-sectional view of the energy absorption mechanism 20 along the longitudinal direction. Here, the longitudinal direction of the energy absorption mechanism 20 is the X direction in FIG. 2, the vertical direction is the Y direction in FIG. 2, and the horizontal direction is the Z direction in FIG. 2. The energy absorption mechanism 20 is attached to the end of the rope 16 to absorb impact energy received by the rope 16. The energy absorption mechanism 20 includes a cylindrical housing 22 with at least one open end, an attachment portion 26 for attaching the housing 22 to the ground G or a fixed object fixed to the ground G, a strip-shaped rigid member 30, friction increasing means, and stopper members 28A and 28B. The friction increasing means is provided in at least one of the housing 22 and the rigid member 30 and increases the frictional force between the rigid member 30 and the inner wall surface of the housing 22. In this embodiment, the friction increasing means is a pressing means 40 that can press the rigid member 30 against the inner surface of the housing and that can adjust the pressing force. The pressing means 40 includes a friction resistance plate 42 and a fastening member 44. Note that Fig. 4 shows the mounting portion 26 in a non-sectional state.

[0041] The housing 22 is formed of a highly rigid metallic material such as steel (e.g., SS material), and in this embodiment, is formed in the shape of a rectangular tube having a hollow rectangular cross section surrounded by four rectangular side walls (first side wall 22a, second side wall 22b, third side wall 22c, and fourth side wall 22d). The length of the housing 22 is appropriately set depending on the length to which the rigid member 30 is deformed when the energy absorption mechanism 20 is activated, i.e., the amount of impact energy that can be absorbed by the energy absorption mechanism 20. As an example, the size (outer diameter dimensions) of the housing 22 can be 100 mm in vertical width (dimension in the Y direction) and 100 mm in horizontal width (dimension in the Z direction), and the length (dimension in the X direction) of the box in which the rigid member 30 is housed can be 1 m.

[0042] One end of the housing 22 is open, and the other end is provided with an attachment piece 24 to which the attachment portion 26 is attached. In the following description, the end of the housing 22 on the open side is also referred to as the opening end 23a, and the end to which the attachment portion 26 is attached is also referred to as the attachment end 23b. In this embodiment, the attachment piece 24 is formed by bending a portion of a plate-like member that forms the second side wall 22b and the fourth side wall 22d, and is formed in a plate shape that protrudes from the cylindrical main body of the housing 22 in the axial direction (X direction).

[0043] The mounting portion 26 is used to mount the housing 22 to the support 12, which is a fixed object fixed to the ground G, and may be, for example, a locking member such as a shackle. As shown in FIG. 1 , in this embodiment, the mounting end 23b of the housing 22 is locked to the intermediate support 12-2 or 12-3 of the protective fence 10 using the mounting portion 26.

[0044] In addition, the end of the rope 16 may be structured to be engaged with an anchor (a fixed object fixed to the ground G) embedded in the ground G, and in such a case, one end of the housing 22 can be attached to the anchor using an attachment portion 26 so that the energy absorption mechanism 20 is interposed between the anchor and the rope 16.

[0045] The rigid member 30 is a strip-shaped member made of a relatively rigid metallic material, such as a steel plate, and has a folded portion 34 folded back into a U-shape within the housing 22. The rigid member 30 is preferably plated on its surface to improve corrosion resistance; for example, a steel plate plated with zinc, aluminum, or magnesium can be used. As shown in FIGS. 2 and 3 , one end of the rigid member 30 is fixed to the housing 22, folded back into a U-shape within the housing 22, and extends while contacting the inner surface of the housing 22, with the other end extending from the opening of the housing 22. The other extended end of the rigid member 30 is connected to the rope 16 in a state in which it is pulled when an impact load is applied to the rope 16. The thickness, width, and length of the rigid member 30 can be set as appropriate; for example, the thickness can be 3 mm to 15 mm, preferably 8 mm to 13 mm, and the width can be 60 mm to 100 mm. The length of the rigid member 30 is set appropriately depending on the length of the housing 22. For example, a rigid member 30 having a length of 1.5 m can be used for a housing 22 having a length of 1 m.

[0046] In the following description, the fixed end of the rigid member 30 will be referred to as the fixed end 31, and the end protruding from the housing opening will be referred to as the movable end 32. The folded extension portion of the rigid member 30 refers to the portion of the rigid member 30 that extends in the X direction from the folded portion 34 to the movable end 32. As will be described later, when the movable end 32 is pulled and moves toward the rope 16, the rigid member 30 undergoes plastic deformation so that the folded portion 34 moves toward the fixed end 31 inside the housing 22.

[0047] The fixed end 31 of the rigid member 30 is fixed to the inner wall surface near the opening of the housing 22 using a fixing member 29. In this embodiment, a bolt and nut are used as an example of the fixing member 29. The folded portion 34 of the rigid member 30 is located near the mounting end 23b of the housing 22, and as shown in FIG. 3, the outer peripheral surface of the rigid member 30 contacts two opposing inner wall surfaces of the housing 22 (the inner wall surfaces of the first side wall 22a and the third side wall 22c). The end of the rope 16 is connected to the movable end 32 of the rigid member 30 using a connecting member 39 such as a shackle.

[0048] 5 is a perspective view of the rigid member 30 housed in the housing 22. The rigid member 30 has a long hole 36 and a plurality of notches 38 formed on the surface facing the inner wall surface of the housing 22 in the region between the one end fixed to the housing 22 and the folded-back portion 34.

[0049] 3, the elongated hole 36 is a hole through which the shaft of the fastening bolt 45 constituting the pressing means 40 passes, and has a width dimension slightly larger than the outer diameter of the shaft. The elongated hole 36 is formed in the center of the rigid member 30 in the width direction, and extends long in the length direction of the rigid member 30.

[0050] A plurality of notches 38 are formed on the surface of the rigid member 30 from the folded portion 34 toward the fixed end 31. The notches 38 extend long in the width direction of the rigid member 30, and are formed at intervals along the length of the rigid member 30. In the example shown in Fig. 5, the notches 38 are formed on both sides of the elongated hole 36, but in areas where the elongated hole 36 is not formed, notches 38 may be formed that extend continuously across the width direction of the rigid member 30.

[0051] A portion of the folded extension portion of the rigid member 30 is pressed against the inner wall surface of the housing 22 by a pressing means 40. The pressing means 40 is disposed in the region between the folded portion 34 and the movable end 32 of the rigid member 30 within the housing 22, and is capable of pressing a portion of the rigid member 30 against the inner wall surface of the housing 22 with any amount of force.

[0052] 6, the pressing means 40 of this embodiment includes a friction resistance plate 42 disposed opposite the inner wall surface of the third side wall 22c of the housing 22 with the rigid member 30 interposed therebetween, and a fastening member 44 capable of fastening the friction resistance plate 42 to the housing 42 with a force of any magnitude. In this embodiment, a fastening bolt 45 and a fastening nut 46 are used as an example of the fastening member 44.

[0053] The friction resistance plate 42 is formed in a flat plate shape and serves to increase the friction resistance generated between the rigid member 30 and the pressing means 40 and housing 22 when the movable end 32 of the rigid member 30 moves. The friction resistance plate 42 can be made of, for example, a resin material, a metal material, or the like. The size of the friction resistance plate 42 can be selected appropriately so that the area that overlaps with the rigid member 30 in the installed state is large or small. A circular through-hole 43 is formed in the center of the friction resistance plate 42, through which the shank of the fastening bolt 45 passes.

[0054] The friction resistance plate 42 is fastened to the housing 22 using a fastening bolt 45 and a fastening nut 46, with the folded-back extension portion of the rigid member 30 interposed between the friction resistance plate 42 and the inner wall surface of the housing 22. In this pressing means 40, the force pressing the rigid member 30 against the housing 22 can be adjusted by changing the fastening force of the fastening member 44. As described above, the fastening bolt 45 passes through the elongated hole 36 of the rigid member 30, and in the initial state of the energy absorption mechanism 20 shown in FIGS. 2 to 4, the fastening bolt 45 is located at the end of the elongated hole 36 on the movable end 32 side of the rigid member 30. In the following description, the end of the elongated hole 36 on the movable end 32 side will also be referred to as the "first end 36a of the elongated hole 36," and the end of the elongated hole 36 on the fixed end 31 side will also be referred to as the "second end 36b of the elongated hole 36."

[0055] The stopper members 28A, 28B restrict the range of plastic deformation of the rigid member 30, and are fixedly installed on the inner surface side of the rigid member 30 within the housing 22. The stopper members 28A, 28B are fixedly installed in the longitudinal direction (X direction) of the housing 22, between the folded portion 34 and the fixed end 31 of the rigid member 30 accommodated within the housing 22, at positions spaced apart from the folded portion 34 toward the fixed end 31. In this embodiment, the first stopper member 28A and the second stopper member 28B are installed in a pair in the vertical direction (Y direction) within the housing 22, and the second stopper member 28B is located between the folded portion 34 of the rigid member 30 and the pressing means 40, in the vicinity of the pressing means 40. In this embodiment, the stopper members 28A, 28B are formed of rod-shaped members that penetrate from the second side wall 22b to the fourth side wall 22d within the housing 22, and in the illustrated example, are configured by a bolt that penetrates the housing 22 and extends in the Z direction and a nut that fixes the bolt to the housing 22. The second stopper member 28B is configured, for example, to be arranged in a state of not contacting the folded-back extension portion of the rigid member 30, so that when the energy absorption mechanism 20 is activated, the folded-back extension portion of the rigid member 30 can pass between the second stopper member 28B and the housing 22 and be pulled toward the rope 16.

[0056] As shown in Fig. 1, the above-mentioned energy absorption mechanism 20 has the housing 22 attached to the attachment portion 14 of the support post 12 using the attachment portion 26. Furthermore, the end of the rope 16 is connected to the movable end portion 32 of the rigid member 30 using a connecting member 39. The rope 16 is stretched over the support post row 11 of the protective fence 10. In the initial state where no tensile force due to falling rocks or the like is acting on the rope 16, the energy absorption mechanism 20 is in the initial state shown in Fig. 3.

[0057] When a falling rock or the like 16 strikes the protective fence 10, an impact load acts on the rope 16, and a tensile force equal to or greater than a predetermined value acts on the rope 16, as shown in FIG. 7A , the movable end 32 of the rigid member 30 is pulled by the rope 16, increasing the length of its protrusion from the housing 22. Specifically, the folded, extended portion of the rigid member 30 slides on the inner wall surface of the housing 22 while receiving a pressing force from the pressing means 40, and is pulled outward from the housing 22. At this time, the friction resistance plate 42 and the fastening member 44 of the pressing means 40 are fixed to the housing 22, and the fastening bolt 45 of the pressing means 40, which penetrates the rigid member 30, moves toward the second end 36b within the elongated hole 36 of the rigid member 30. Furthermore, as the movable end 32 of the rigid member 30 is pulled, plastic deformation occurs in the rigid member 30, changing the position of the U-shaped folded portion 34 within the housing 22.

[0058] 5, in this embodiment, the rigid member 30 has notches 38 formed in the region where it undergoes plastic deformation, and therefore the rigid member 30 can be bent sequentially along the notches 38. This makes it possible to prevent the rigid member 30 from being bent into an unintended shape and reducing its energy absorption performance when it undergoes plastic deformation due to an impact load.

[0059] 7B, as the plastic deformation of rigid member 30 progresses, folded portion 34 abuts against stoppers 28A, 28B, thereby stopping the plastic deformation of rigid member 30. This applies a braking force to rope 16 that stops the pulling movement of rope 16.

[0060] In the above-described energy absorption mechanism 20, impact energy can be absorbed by the frictional resistance between the rigid member 30 and the inner wall surface of the housing 22. Furthermore, because the rigid member 30 is pressed against the housing 22 by the pressing means 40, the frictional resistance between the rigid member 30 and the housing 22 can be increased, thereby improving the impact energy absorption performance. Furthermore, the energy absorption mechanism 20 can also absorb impact energy by plastic deformation of the rigid member 30. In this way, the energy absorption mechanism 20 can absorb impact energy by the frictional resistance and plastic deformation generated in the rigid member 30, thereby achieving high impact energy absorption performance.

[0061] Furthermore, the magnitude of the frictional resistance force generated between the rigid member 30 and the inner wall surface of the housing 22, i.e., the amount of energy absorbed, can be easily changed by adjusting the magnitude of the pressing force applied by the pressing means 40. Specifically, the pressing force acting on the rigid member 30 can be increased or decreased by increasing or decreasing the fastening force applied by the fastening members 44. In this way, with the energy absorption mechanism 20 of this embodiment, the impact energy absorption performance can be changed without changing the design of the rigid member 30.

[0062] In this embodiment, the pressing means 40 is composed of the friction resistance plate 42 and the fastening member 44, but the pressing means 40 may not have the friction resistance plate 42 and may be composed of only the fastening member 44. Even in this case, the magnitude of the friction resistance force generated between the rigid member 30 and the inner wall surface of the housing 22 can be adjusted by adjusting the tightening force of the fastening member 44.

[0063] Furthermore, in the energy absorption mechanism 20 of this embodiment, the initial load when the energy absorption mechanism 20 operates can be reduced compared to a conventional structure in which a rigid member is plastically deformed via a pin member fixed to a housing, so impact energy can be absorbed smoothly and stably from the initial operation. Furthermore, while conventional structures cannot control the magnitude of the braking force, the energy absorption mechanism 20 of this embodiment, as described above, can control the magnitude of the braking force by controlling the frictional force using the tightening force of the fastening members 44.

[0064] Furthermore, when the friction resistance plate 42 is provided in addition to the fastening member 44 as in this embodiment, a large frictional resistance force can also be generated between the rigid member 30 and the frictional resistance plate 42, thereby further improving the energy absorption performance. Furthermore, the magnitude of the frictional resistance force (the amount of energy absorbed) can be appropriately adjusted by changing the contact area between the frictional resistance plate 42 and the rigid member 30, the material of the frictional resistance plate 42, and the tightening force of the fastening member 44, thereby widening the adjustment range of the energy absorption performance.

[0065] Furthermore, after operation has finished, the energy absorption mechanism 20 can be reused by replacing only the plastically deformed rigid member 30. In a conventional structure in which a fixed pin member is used to plastically deform a rigid member, it was necessary to replace not only the rigid member but also the entire assembly, including the pin member and the housing that secures it. However, the energy absorption mechanism 20 of this embodiment reduces the number of replacement parts, thereby reducing maintenance costs.

[0066] (Second embodiment) Next, a second embodiment of the energy absorption mechanism 20 will be described with reference to Figures 8 and 9. In this embodiment, the housing 22 is provided with buckling prevention means 50 that is movable while abutting against the folded portion 34 of the rigid member 30 when the rigid member 30 undergoes plastic deformation. Note that, in the embodiment shown in Figures 8 and 9, other configurations are similar to those of the first embodiment described above, and therefore description thereof will be omitted here.

[0067] The buckling prevention means 50 is provided in the housing 22 and includes a cylindrical pin member 52 that abuts against the inner surface of the folded portion 34 of the rigid member 30, and a guide member for moving the pin member 52 along the length direction of the housing 22. The guide member includes a guide hole 54 formed in the housing 22, and a support shaft 56 that passes through the guide hole 54 and supports the pin member 50.

[0068] The guide holes 54 are formed in pairs in the second side wall 22b and the fourth side wall 22d of the housing 22, and are through holes that extend linearly in the longitudinal direction of the housing 22. The support shaft 52 supports both ends of the pin member 52 while passing through the pair of guide holes 54. The pin member 52 is disposed within the housing 22 so that its peripheral surface abuts against the folded portion 34 of the rigid member 30.

[0069] In the energy absorption mechanism 20 equipped with the above-described buckling prevention means 50, when the energy absorption mechanism 20 is activated and plastic deformation occurs in which the position of the folded portion 34 of the rigid member 30 shifts, the pin member 52 is pushed by the folded portion 34 of the rigid member 30 and moves along the guide hole 54 toward the open end 23a of the housing 22 while abutting against the folded portion 34, as shown by the arrow in Figure 9. Because the rigid member 30 is bent into a U-shape along the circumferential surface of the pin member 52 during plastic deformation, buckling at the folded portion 34 can be prevented.

[0070] (Third embodiment) Next, a second embodiment of the energy absorption mechanism 20 will be described. FIG. 10 is a longitudinal cross-sectional view similar to FIG. 3, showing a third embodiment of the energy absorption mechanism 20. In this embodiment, the rigid member 30 is composed of a plurality of strip plate materials 30A, 30B that are separably stacked. In FIG. 10, two strip plate materials 30A, 30B are shown as the rigid member 30, but the number of strip plate materials 30A, 30B may be three or more. In the embodiment shown in FIG. 10, the configuration other than the rigid member 30 is the same as in the first embodiment described above, and therefore description thereof will be omitted here.

[0071] Like the rigid member 30 of the first embodiment, each strip plate 30A, 30B has a fixed end 31, a folded portion 34, and a movable end 32. Each strip plate 30A, 30B has a slot 36 through which a fastening bolt 45 passes and a plurality of notches 38. Here, of the two strip plate materials 30A, 30B, the strip plate in contact with the housing 22 is referred to as the first strip plate 30A, and the strip plate disposed inside it is referred to as the second strip plate 30B. As shown in FIG. 10 , the first strip plate 30A and the second strip plate 30B are spaced apart at the folded portion 34 and are stacked in contact between the fixed end 31 and the folded portion 34 and at the folded extension portion. The end of the rope 16 is connected to the movable end 32 of each strip plate 30A, 30B using a connecting member 39. The strip plate materials 30A, 30B have approximately the same length and width. The thickness of each strip plate material 30A, 30B may be the same, or may be set to different thicknesses such that the first strip plate material 30 is thicker or thinner than the second strip plate material 30B. The thickness of each strip-shaped member 30A, 30B may be, for example, 2 mm to 5 mm.

[0072] In the energy absorption mechanism 20 of this embodiment, the rigid member 30 is formed from a plurality of strip plate materials 30A, 30B, which allows the thickness of each strip plate material 30A, 30B to be thin, thereby encouraging each strip plate material 30A, 30B to bend sequentially into a perfect U-shape during plastic deformation. Furthermore, by spacing the folded portions 34 apart, it is possible to prevent the folded portions 34 from interfering with each other during plastic deformation and hindering deformation.

[0073] (Fourth embodiment) Next, a fourth embodiment of the energy absorption mechanism 20 will be described. Fig. 11 is a vertical cross-sectional view similar to Fig. 3, showing the third embodiment of the energy absorption mechanism 20. In this embodiment, high friction resistance layers 27, 37 having high friction resistance are provided on the inner wall surface of the housing 22 and the surface of the rigid member 30. Note that the other configurations of the embodiment shown in Fig. 11 are the same as those of the first embodiment described above, and therefore will not be described here.

[0074] The high friction resistance layers 27, 37 each constitute a friction increasing means for increasing the friction resistance force between the rigid member 30 and the housing 22. In this embodiment, a first high friction resistance layer 27 having a higher friction resistance than the inner wall surface of the housing 22 is provided on the inner wall surface of the housing 22 facing the folded extension portion of the rigid member 30, i.e., the inner wall surface of the third side wall 22c, and a second high friction resistance layer 27 having a higher friction resistance than the surface of the rigid member 30 facing the inner wall surface of the housing 22 is provided on the surface of the rigid member 30 facing the inner wall surface of the housing 22.

[0075] The first and second high friction resistance layers 27, 37 are each made of a material different from that of the housing 22 and the rigid member 30. The first and second high friction resistance layers 27, 38 can be made of a metal material such as aluminum or a resin material that is softer than the surfaces of the housing 22 and the rigid member 30 to which they are attached. The second high friction resistance layer 37 has an elongated hole 37a formed in a region overlapping with the elongated hole 36 of the rigid member 30, through which the fastening bolt 45 passes.

[0076] In the energy absorption mechanism 20 of this embodiment, when the movable end 32 of the rigid member 30 is pulled outward from the housing 22, the first and second high friction resistance layers 27, 37 can increase the friction resistance force generated when the rigid member 30 slides on the inner wall surface of the housing 22, thereby achieving higher impact energy absorption performance.

[0077] The high friction resistance layers 27, 37 may be provided only on either the rigid member 30 or the housing 22. In this embodiment, the high friction resistance layers 27, 37 may be formed by roughening the surfaces of the rigid member 30 or the housing 22.

[0078] (Fifth embodiment) Next, a fourth embodiment of the energy absorption mechanism 20 will be described. Fig. 12A is a vertical cross-sectional view similar to Fig. 3, showing the fourth embodiment of the energy absorption mechanism 20. In the embodiment shown in Fig. 12A, the configuration other than the rigid member 30 is the same as that of the first embodiment described above, and therefore description thereof will be omitted here.

[0079] The rigid member 30 of this embodiment is formed so that its thickness increases from the folded portion 34 toward the fixed end 31. The region where the thickness increases is preferably at least the region where the rigid member 30 undergoes plastic deformation when the energy absorption mechanism 20 is activated, i.e., the region from the folded portion 34 toward the fixed end 31 where the stopper 28A is disposed. In the illustrated example, the rigid member 30 is formed so that its thickness gradually increases toward the fixed end 31. For example, the thickness can be increased by approximately 0.2 mm to 3 mm, preferably approximately 0.5 mm to 2 mm, at the position of the stopper 28A relative to the thickness of the folded and extended portion. Note that in FIG. 12A, the increase in thickness is emphasized for ease of understanding.

[0080] In this way, by gradually increasing the thickness of the rigid member 30 in the region where the rigid member 30 undergoes plastic deformation, when the energy absorption mechanism 20 is activated and plastic deformation occurs that changes the position of the folded portion 34, the amount of energy absorbed by the plastic deformation gradually increases, thereby achieving higher energy absorption performance.

[0081] FIG. 12B is a perspective view showing a modified example of the rigid member 30 in the fifth embodiment. As shown in the example, the rigid member 30 may be formed so that its thickness is increased by stacking one or more plate materials from the folded portion 34 toward the fixed end 31. In the example shown, three plate materials 33A, 33B, and 33C of different lengths are stacked to increase the thickness of the rigid member 30. In the example shown, the width of each plate material 33A to 33C is set to the same dimension as the width of the rigid member main body having the folded portion 34, but the width dimension may be smaller than that of the rigid member main body. The thickness of the stacked plate materials 33A to 33C is preferably thinner than the base material of the rigid member 30 on which the folded portion 34 is formed. Furthermore, the thickness of each plate material 33A to 33C may be the same or different. It is preferable to provide a notch 38 on the surface of the stacked plate materials 33A to 33C, which makes it easier to bend the rigid member 30 into a U-shape during plastic deformation. In the illustrated example, the plate materials 33A to 33C are laminated on the outer surface of the rigid member body (the surface facing the inner wall surface of the housing 22), but they may also be laminated on the inner surface of the rigid member body, or on both the outer and inner surfaces.

[0082] (Sixth embodiment) Next, a fifth embodiment of the energy absorption mechanism 20 will be described. Fig. 13 is a vertical cross-sectional view similar to Fig. 3 showing the fifth embodiment of the energy absorption mechanism 20. In this embodiment, the shape of the internal space of the housing 22 is different from that of the first embodiment. Note that in the embodiment shown in Fig. 13, the configuration other than the housing 22 is the same as that of the first embodiment described above, and therefore description thereof will be omitted here.

[0083] In this embodiment, the housing 22 has an inner wall surface that comes into contact with the rigid member 30 that is inclined so that the area of ​​the closed cross section decreases toward the open end (open end 23a). In the illustrated example, the inner wall surface of the third side wall 22c that comes into contact with the folded-back extension portion of the rigid member 30 is inclined so that the opening area on the open end 23a side decreases. Alternatively or in addition to this, the inner wall surface of the first side wall 22a that comes into contact with the rigid member 30 may be inclined so that the area of ​​the closed cross section decreases.

[0084] In this embodiment, when the energy absorption mechanism 20 is activated and plastic deformation occurs that changes the position of the folded portion 34 of the rigid member 30, the rigid member 30 deforms so that the radius of curvature of the folded portion 34 gradually decreases along the inclined inner wall surface of the housing 22. This allows the amount of energy absorption of the rigid member 30 to gradually increase, thereby improving the energy absorption performance of the energy absorption mechanism 20.

[0085] As shown in the above-described embodiments, in the energy absorption mechanism 20 according to the present invention, the operating load of the energy absorption mechanism 20 can be easily controlled by appropriately changing the shape and structure of the rigid member 30, the pressing means 40, and / or the housing 22. In the conventional energy absorption mechanism described in Patent Document 2, the operating load is large initially and then decreases, resulting in large variations in the initial load even with the same shape and structure. In contrast, in the energy absorption mechanism 20 according to the present invention, the initial load can be reduced to suppress variations, and the operating load can be controlled to be approximately uniform or to gradually increase during the operation of the energy absorption mechanism 20.

[0086] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the invention.

[0087] For example, the pressing means 40 and the first and second high-friction resistance layers 27, 37, which are friction-increasing means, are optional, and the energy absorption mechanism may be configured without the friction-increasing means. The energy absorption mechanism 20 according to the present invention may also be configured by combining the above-described embodiments. For example, the first and second high-friction resistance layers 27, 37 can be applied to the embodiment shown in FIG. 12A, 12B, or 13, and the rigid member 30 shown in FIG. 12A or 12B may be applied to the embodiment shown in FIG. 13.

[0088] Furthermore, for example, the energy absorption mechanism 20 may have a structure in which the end of the rope 16 is connected to the mounting portion 26, and the movable end 32 of the rigid member 30 is attached to a fixed object fixed to the ground G using a connecting member 39 or the like. [Explanation of symbols]

[0089] 10 Protective fence 11 column row 12 pillars 16 Rope 18 Spacing member 20 Energy absorption mechanism for ropes 22 Housing 26 Mounting part 27 First high friction resistance layer (friction increasing member) 28A, 28B Stopper member 30 Rigid member 31 Fixed end 32 Movable end 34 Folded section 36 long hole 38 Cutting 37 Second high friction resistance layer (friction increasing member) 40 Pressing means (friction increasing means) 42 Friction resistance plate 44 Fastening members 45 Fastening bolt 46 Fastening nut 50 Buckling prevention means G Ground

Claims

1. A rope energy absorption mechanism is provided on a safety fence that receives load impacts using a tensioned rope and absorbs impact energy applied to the rope, a cylindrical housing having at least one open end; an attachment portion for attaching the housing to either a fixed object fixed to the ground or a rope; a rigid member in the shape of a strip, one end of which is fixed to the housing and the other end of which extends from the opening of the housing, the rigid member having a folded portion folded back in a U-shape within the housing, the outer surface of the folded extension portion being the portion of the rigid member from the folded portion to the other end side being in contact with the inner wall surface of the housing; and An energy absorption mechanism for a rope, characterized in that the other end of the rigid member is connected to either the fixed object or the rope in a state in which the other end is pulled outward from the housing when an impact load is applied to the rope.

2. 2. The energy absorption mechanism for a rope according to claim 1, further comprising a friction increasing means provided on at least one of the housing and the rigid member for increasing the friction force between the rigid member and the inner wall surface of the housing.

3. 3. The energy absorption mechanism for a rope according to claim 2, wherein the friction increasing means includes a pressing means capable of pressing the outer surface of the folded extension portion of the rigid member that contacts the inner wall surface of the housing against the inner wall surface of the housing, and the pressing force is adjustable.

4. The pressing means is a friction resistance plate disposed opposite the inner wall surface of the housing with the rigid member interposed therebetween; 4. The energy absorption mechanism for a rope according to claim 3, further comprising a fastening member capable of fastening the friction resistance plate to the housing with a force of any magnitude.

5. The energy absorption mechanism for a rope according to any one of claims 2 to 4, characterized in that the friction increasing means includes a high friction resistance layer provided on an outer surface of the rigid member facing the inner wall surface of the housing and / or on an inner wall surface of the housing facing the folded-back extension portion of the rigid member, the high friction resistance layer having greater friction resistance than the rigid member and / or the housing.

6. The energy absorption mechanism for a rope according to any one of claims 1 to 5, characterized in that the rigid member is formed so that its plate thickness increases from the folded portion toward the fixed one end.

7. The energy absorption mechanism for a rope according to any one of claims 1 to 6, characterized in that the inner wall surface of the housing that comes into contact with the rigid member is inclined so that the area of ​​the closed cross section of the housing becomes smaller toward the open one end.

8. The energy absorption mechanism for a rope according to any one of claims 1 to 7, characterized in that the rigid member has a plurality of notches extending in a width direction of the rigid member on an outer surface facing the inner wall surface of the housing in a region between the one end fixed to the housing and the folded-back portion.

9. 9. The rope energy absorption mechanism according to any one of claims 1 to 8, characterized in that it further comprises a pin member that is provided in the housing, has a cylindrical shape with a peripheral surface that abuts against the inner surface of the folded-back portion of the rigid member, and that, when activated, moves within the housing toward the opening while abutting against the inner surface of the folded-back portion.

10. The energy absorption mechanism for a rope according to any one of claims 1 to 9, characterized in that the rigid member is composed of a plurality of strip plate materials that are separably stacked at least in the area where the folded portion is formed.

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