AU2004200724B2 - Energy absorbing device - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S):: Peter Michael Fitzgerald ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys Level 10, 10 Barrack Street,Sydney, New South Wales, Australia, 2000 INVENTION TITLE: Energy absorbing device The following statement is a full description of this invention, including the best method of performing it known to me/us:- P.\WPDOCS\ARSISPECIE\122ZO361_ Pic FiugeeldIs1SPA do.410MlO 00 -1- ;Z ENERGY ABSORBING DEVICE The present invention relates generally to energy absorbing devices and more particularly to a height safety device for use in the event of a fall, to increase the time over which energy is absorbed by, for example, anchor points and cable.

It is known that lengthening the time over which an impact occurs to a body alleviates damage and injuries to the body, as it reduces the maximum force that is imparted to the body. Examples may be found in situations such as, for example, passenger vehicle accidents, falls from heights, and other transportation accidents such as with trains, and the like. Some solutions exist for arresting falls in a manner which alleviate injuries, however, are complex in design, use exotic materials, and are expensive.

The present invention seeks to alleviate one or more of the abovementioned disadvantages.

According to one aspect of the present invention there is provided a clamping assembly for mounting the device to a structure the clamping assembly comprising two clamping arms adapted to clamp at least a part of the structure therebetween; a bearing member associated with one of the clamping arms said bearing member including a bearing surface; a collapsible member which is adapted to bear against the bearing surface of the bearing member; a load support member mounted for displacement relative to bearing member under a load applied thereto, said load support being operatively connected to the collapsible member such that when a load in a load range is applied to said load support the collapsible portion can deform in an elastic fashion and when a load in excess of the load range is applied the collapsible portion can deform in a plastic fashion.

In one form the collapsible member may comprise a base wall having two spaced apart props extending laterally from the base wall, the ends of said legs remote from said base wall being adapted to operatively bear against said bearing surface, said load support member being operatively connected to said base wall.

P %WPDOCS'ARS SPECIEI 2220361_Pw, F.gaIdl1SPAdo4A)82008 00

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Each clamping arm may comprise a structure receiving section and a mounting t flange, the mounting flanges of said clamping arms being securable together by one or more fastening elements at least part of one of the flanges defining the bearing member.

The load support device may comprise an elongated rod one end portion thereof being operatively connected to the collapsible member and having a stop thereon which acts on the collapsible member under a load applied to the load support device.

Each clamping arm includes a channel-shaped portion which is adapted to receive at least part of the structural member therein, and at least one said mounting flange which extends laterally from the channel-shaped section. Each clamping arm may comprise two mounting flanges which extend laterally from opposite sides of the channel shaped section.

Preferably the clamping arms are elongated members having opposed ends wherein said channel shaped portion and said mounting flanges extend from one said end portion to the other, said collapsible member being disposed generally intermediate the ends of the flange of one of the clamping arms and wherein fasteners are adapted to be secured to the flanges towards the ends thereof.

The fasteners may be in the form of bolts and cooperating nuts which pass through apertures in the flanges of the clamping arms. An eye bolt may be operatively connected to the load support member and is adapted to have attached thereto safety lines or cables.

A plurality of collapsible members may be provided which are arranged together in a nested relationship.

According to another aspect of the present invention there is provided an energy absorbing device including: a chassis, the chassis including a bearing section; a collapsible portion mounted on the bearing section; support means for a load, the support means including a support connection spaced from the bearing section wherein under a selected P:\WPDOCS\LMB\LAer MiI04\Spmirk.tiousI2220361 fltgaald.dm-24 February. 2004 -2load range, elastic deformation of the collapsible portion occurs, and in excess of that load range, the collapsible portion plastically collapses, the support connection collapsing towards the bearing section.

Preferably the bearing section is in the form of a plate section, for the purpose of spreading the load and alleviating a pull-through failure.

The plate section may incorporate a clamp section in order to clamp to structural roof members including rafters. The clamp section may be in the form of operatively connected top-hat sections, the top-hat sections including a hollow section and flanges on either side thereof. Two similar top-hat sections are provided to clamp to a structural member, the flange sections when clamped being generally abutting or at least adjacent with the hollow section accommodating the rafter. The two top-hats form a clamp by being held together through the flanges by bolted connections.

In other embodiments, the plate section is fastened to the structural members directly, by passing fasteners through the plate and into the structural member. This may occur in the case of metal purlins.

The collapsible section may be in any suitable one-shot deforming or crumpling form, and is preferably a generally saddle-shaped section, having two end portions operatively connected to the bearing section at each end portion.

Preferably, the saddle-shaped sections include 2 spaced-apart props, and a support wall connected at corresponding ends of the props and extending therebetween. In preferred forms, the props are perpendicular to the support wall. In one embodiment radiused arms are provided at the connection between support wall and props, and the saddle-shaped section is formed from a length of Rectangular Hollow Section, cut along two opposed walls.

In preferred forms, the or each saddle-shaped section is welded at their ends to the P:\WPDOCS\LMB\Lcster Milla\Spemications\12220361 fgiald.dm-24 Febmuay. 2004 -3bearing section, by, for example, spot welding, slot welding, or drill-and-plug welding.

Preferably, operative connections are in the form of through holes in the bearing section and collapsible portion. The through holes are preferably collinear, and the hole in the saddle section is preferably disposed generally in the center of the saddle, when traversing between its ends.

The chassis may be constructed from any suitable material, including metals, preferably steel or weldable alloys thereof.

Preferably, support means are in the form of, for example, eye bolts for the purpose of attaching safety lines or cables so that a person or object may be secured to the collapsible portion, the eye bolts preferably passing through the collinear through holes, and secured by nuts and washers.

In preferred forms, one or more saddle-shaped sections are provided, and nested, so that collapse threshold and behaviour may be altered and controlled. Also, the relative strengths and thicknesses of the component props and walls of the saddle-shaped sections may vary. In this way, an outer saddle which generally supports the static load, may be the strongest and thickest of the saddles, which, during collapse, to then impact with thinner and thus weaker saddle sections to provide some further arrest of, for example, a fall.

In order to enable a clearer understanding of the invention, drawings of exemplary embodiments are provided, and in those drawings: Figure 1 is a front elevation view of the device; Figure 2 is a front elevation view of a second embodiment of the device, being for heavier loads than that shown in Figure 1; Figure 3 is a front elevation view of a third embodiment of energy absorbing P\\fPDOCSXARS.SPECIE\I2220)361Pc F.Ugald I ISPA dx4MM)008 00 -4device, being for heavier loads than those shown in Figures 1 and 2; Figure 4 is a bottom plan view of an alternate arrangement of the device, where the collapsible portion includes nested or clustered saddles; Figure 5 is a front elevation view of the device in situ, clamped to a structural member; Figure 6 is a side elevation view of the embodiment shown in situ in Figure Figure 7 is an underside isometric view of the embodiment shown in Figure 5 and Figure 6; Figure 8 shows results of testing of the embodiment shown in Figures 1 and 5 7.

Referring to Figure 1 there is shown an energy absorbing fall arresting device generally indicated at 10 having a chassis 12, the chassis 12 having a bearing section in the form of a plate 14 and a collapsible portion 16. The collapsible portion 16 is in the form of a saddle shaped section 18 having two ends 17 and 19 and operatively connected by welding at its ends 17 and 19 to the bearing section 14. A support wall 15 is connected to props 21 and 23 at ends and 27, so that the support wall 15 is spaced from the bearing section, to provide a crumpling distance. Props 21 and 23 are perpendicular to support wall Operative connections in the form of collinear through holes 26 and 28 are provided to connect load support means 31. The through hole 28 is of a diameter smaller than the outside diameter of nut and washer 24 so that a support connection 25 is provided to assist with supporting load 39. Hole 28 is generally in the center of the saddle section 18, the centre being half the distance from end 17 to end 19.

A securing point is provided in the form of eye bolt 22, which passes through collinear holes 26 and 28 and retained by nuts and washers 24. The securing point is for P:\WPDOCS\LMB\Leser Mill fSpificaions12220361 irLzgarald.doc-24 February, 2004 securing loads and potential loads 39 such as a worker on a roof, via, for example, chains, carabiners, webbing (all not shown).

The plate 414 in Figures 5 to 7 is integral with a clamp section 490 in order to clamp to structural roof members including rafters 450. The clamp section 490 is in the form of operatively connected top-hat sections 470 and 472, the top-hat sections including hollow sections 474 and 476 respectively and flanges 478, 480, 482 and 484, each on either side of the hollow sections. Two similar top-hat sections 470 and 472 are provided to clamp to the structural member 450, the flange sections 478 484 when clamped being generally abutting or at least opposed or adjacent with the hollow sections 474 and 476 accommodating the rafter 450. The two top-hats form a clamp by being held together through the flanges by bolted connections, bolts 445, 422 and 442.

Other embodiments of the energy absorbing device are shown in Figures 2-7, and like numerals depict like parts in those Figures. Collapsible sections (116, 216, etc) is shown in the form of nested saddle-shaped sections (118, 220, etc), the arrangement of which affects collapse behaviour. There are provided examples of parallel nests (Figure 4) and series nests (Figures 2 and 3).

In use, referring to Figure 6, for example in height safety, the chassis 412 as depicted in Figure 5 is secured by clamping to a structural member 450 by bolts 440, 442, 445 and in some cases eye bolt 422, all passing through bearing section 414. The eye 452 of the eye bolt 422 generally points downwards or along a roofline (towards the ground when a worker is working above ground). A worker wearing a harness would pass a securing device such as for example a carabiner (not shown) through eye 452, and connect the carabiner to the harness via ropes or cables. Should the worker loose their footing and fall, the rope and harness would arrest their fall before striking the ground, because the worker is anchored to a structural member 450 through the bearing structure 414. The energy absorbing device would also alleviate injury in the fall, wherein the impact load through the eye bolt 422 and nut and washer 424 causes the saddle 418 to plastically collapse, after a selected load has been reached. This lengthens impact time and reduces P kWPDOCSARSSPECIE'I 222061-Pcie Fiupgald_ I nSPAdm4)MI208 00 -6maximum impact force imparted to the body of the worker.

In the case of multiple saddles (Figs 2 we first turn to series nesting (Figs 2 and The first saddle may collapse when a selected load is exceeded, the first saddle deforming generally until the support wall 115 contacts or abuts the second support wall 115a, 215a. The load is then taken by the second saddle 220. It may be that the second saddle collapses immediately thereafter, after some elastic deformation of the second saddle. This allows some addition load dissipation. The process is repeated for the third (Ni saddle if installed.

The parallel nesting case is shown in Figure 4 wherein all load is generally simultaneously taken by all four saddles 318, 318A, 320, 320A, providing additional strength.

Testing of the device shown in Figures 1 and 5 -7 has yielded results such as for example those shown in the graph of Figure 8.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Finally, it is to be understood that various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention.

Claims (11)

1. A fall arresting device comprising: a clamping assembly for mounting the device to a structure the clamping assembly comprising two clamping arms adapted to clamp at least a part of the structure therebetween; a bearing member associated with one of the clamping arms said bearing member including a bearing surface; a collapsible member which is adapted to bear against the bearing surface of the bearing member; a load support member mounted for displacement relative to the bearing member under a load applied thereto, said load support being operatively connected to the collapsible member such that when a load in a load range is applied to said load support the collapsible portion can deform in an elastic fashion and when a load in excess of the load range is applied the collapsible portion can deform in a plastic fashion.

2. A device according to claim 1 wherein said collapsible member comprises a base wall having two spaced apart props extending laterally from the base wall, the ends of said legs remote from said base wall being adapted to operatively bear against said bearing surface, said load support member being operatively connected to said base wall.

3. A device according to claim 1 or claim 2 wherein each said clamping arm comprises a structure receiving section and a mounting flange, the mounting flanges of said clamping arms being securable together by one or more fastening elements at least part of one of the flanges defining the bearing member.

4. A device according to any preceding claim wherein said load support device comprises an elongated rod one end portion thereof being operatively connected to the collapsible member and having a stop thereon which acts on the collapsible member under a load applied to the load support device.

A device according to any preceding claim wherein each said clamping arm PAWPDOCS ARSISPECIE1I 2220361 jPe Frugld I USPA doMAI2(X)8 00 -8- includes a channel-shaped portion which is adapted to receive at least part of the structural Smember therein, and at least one said mounting flange which extends laterally from the channel-shaped section.

6. A device according to claim 5 wherein each clamping arm comprises two said mounting flanges which extend laterally from opposite sides of the channel shaped section.

7. A device according to claim 5 or claim 6 wherein the clamping arms are elongated members having opposed ends wherein said channel shaped portion and said mounting flanges extend from one said end portion to the other, said collapsible member being disposed generally intermediate the ends of the flange of one of the clamping arms and wherein fasteners are adapted to be secured to the flanges towards the ends thereof.

8. A device according to claim 7 wherein the fasteners are in the form of bolts and cooperating nuts which pass through apertures in the flanges of the clamping arms.

9. A device according to any preceding claim wherein an eye bolt is operatively connected to the load support member and is adapted to have attached thereto safety lines or cables.

A device according to any preceding claim wherein there is provided a plurality of collapsible members which are arranged together in a nested relationship.

11. A fall arresting device substantially as hereinbefore described with reference to the accompanying drawings.