To protect workers that have to work at heights, lifelines coupled to safety harnesses donned by a worker are typically used. If a fall event occurs, the lifeline coupled to a support structure limits the fall of the worker. Injury to the worker can occur when the fall distance, before the lifeline becomes taut, is significant. Energy absorbers have been added to lifeline systems to provide a less abrupt stop to help reduce or prevent injuries. An energy absorber absorbs some of the kinetic energy of the falling body.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an effective and efficient and energy absorbing system that fits in a relatively small package.
The above-mentioned problems of current systems are addressed by embodiments of the present invention and will be understood by reading and studying the following specification. The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the invention.
In one embodiment, an energy absorber is provided. The energy absorber includes a first energy absorbing webbing, a second energy absorbing webbing and a plurality of connecting fibers. The plurality of connecting fibers couple at least a portion of the first energy absorbing webbing to at least a portion of the second energy absorbing webbing. The plurality of connecting fibers are configured and arranged to form at least two different tear strength areas in the at least one portion of the first energy absorbing webbing coupled to the at least one portion of the second webbing. The at least two different tear strength areas having select tear strengths.
In another embodiment, another energy absorber is provided. The energy absorber includes a first energy absorbing webbing, a second energy absorbing webbing, a plurality of connecting fibers and first and second attaching webbings. The first energy absorbing webbing has a length that is defined between a first end and a second end. The first energy absorber further has a first mid portion that is centrally located between the first end and the second end. The second energy absorbing webbing is positioned along the length of the first energy absorber. The second energy absorbing webbing has a length that is defined between a first and second end. The second energy absorbing webbing has a second mid portion that is centrally located between the first and the second end of the second energy absorbing webbing. The second mid portion of the second energy absorbing webbing is aligned with the first mid portion of the first energy absorbing webbing. The plurality of connecting fibers connect the first energy absorbing webbing to the second energy absorbing webbing. In particular, the plurality of connecting fibers connect the first energy absorbing webbing to the second energy absorbing webbing between respective first ends of the first and second energy absorbing webbings and the respective mid portions and between respective second ends of the first and second energy absorbing webbings and the respective mid portions. The plurality of connecting fibers are configured and arranged to form at least two different tear strength areas in the first and second energy absorbing webbings. The first attaching webbing is coupled to the first mid portion of the first energy absorber and the second attaching webbing is coupled to the second mid portion of the second energy absorber.
In still another embodiment, a lifeline system is provided. The lifeline system includes a lifeline and an energy absorber. The lifeline is configured and arranged to be coupled between a support structure and a safety harness. The lifeline includes a back strap portion and an energy absorber system. The energy absorbing system includes a first webbing, a second webbing, a first attaching webbing, a second attaching webbing and connecting fibers. The second webbing is coupled along a first webbing length of the first webbing. The first attaching webbing is coupled between a first mid portion of the first webbing and a first end of the back strap portion of the lifeline. The second attaching webbing is coupled between a second mid portion of the second webbing and a second end of the back strap portion of the lifeline. The second mid portion of the second webbing is aligned with the first mid portion of the first webbing forming first and second webbing connection portions of generally equal lengths on either side of the respective first and second mid portions of the first and second webbings.
The connecting fibers couple the first webbing to the second webbing. The connection fibers form a first tear strength area, a second tear strength area and a transition tear area in each of the first and second webbing connection portions of the first and second webbings. The first tear strength area has a tear strength less than the tear strength of the second tear strength area. The transition tear strength area has a tear strength between the first tear strength and the second tear strength. Each first tear strength area is positioned adjacent an associated first and second mid portion of the first and second webbings. The transition tear strength area is further positioned between the first and second tear strength areas.
The present invention can be more easily understood and further advantages and uses thereof will be more readily apparent, when considered in view of the detailed description and the following figures in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the present invention. Reference characters denote like elements throughout Figures and text.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the inventions may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the claims and equivalents thereof.
Embodiments of the present invention provide an energy absorbing system to reduce or prevent an injury when an associated lifeline becomes taut during a fall event. Embodiments of the present invention absorb energy by tearing apart a pair of webbings that are connected together. The pair of webbings are coupled together by connecting fibers. In one embodiment, the energy absorber is a two phase energy absorber having at least two different tear strength areas. A side perspective view of a portion of a lifeline assembly 100 of one embodiment is illustrated in
Referring to
As illustrated by the arrow A in
The differing tear strength areas 410a, 410t and 410b are designed to control the rate of tear while maintaining the integrity of the energy absorption system during a fall event. In one embodiment, the tear strength area 410a tears apart at less of a force than tear strength area 410b. Tear strength area 410t provides a transition between the tear strength of area 410a and area 410b. The transition area 410t helps prevent either of the first and second webbings 223 and 220 from themselves ripping apart which could happen at an abrupt tear strength change point. The tear strengths in the tear strength areas 410a, 410t and 410b can vary depending on the intended use and the desired energy absorption of the device. In one example embodiment, the force needed to tear the webbings 223 and 220 apart from each other in tear strength area 410a is approximately in a range of 500 lbs to 900 lbs, while the force needed to tear the webbings 223 and 220 apart from each other in tear strength area 410b is in a range of approximately 1400 lbs to 1800 lbs. In one embodiment, the force needed to tear the webbings 223 and 220 apart from each other in tear strength area 410a is approximately 500 lbs, while the force needed to tear the webbings 223 and 220 apart from each other in tear strength area 410b is approximately 1600 lbs. In another embodiment, the force needed to tear the webbings 223 and 220 apart from each other in tear strength area 410a is under 800 pounds while the force needed to tear the webbings 223 and 220 apart from each other in tear strength area 410b is under 1700 pounds. Further, in an example embodiment, webbings 220 and 223 have a width of approximately 1.35 inches with the mid portions 220c and 223c of the webbing being approximately 6 inches long and each side 210a and 210b of the energy absorbing webbing 210 having a first tear strength area 410a length of approximately 5 inches, a transition tear strength area 410t of approximately 0.75 of an inch and a second tear strength area 410b length of approximately 15.375 inches. The width of the webbings 223 and 220 and the lengths of the tear strength areas 410a, 410t and 410b are selected depending on the application. Moreover, the tear strengths can be selected to achieve a desired outcome or to conform to standards set by OSHA, ANSI or any other regulating body.
Different methods can be used to achieve the different tear strength areas 410a, 410t and 410b. For example, referring to
In use, if a fall event should occur, once the lifeline 104 becomes taut, the second attachment webbing 204 coupled to the mid portion 223c of the second energy absorbing webbing 223 holds the mid portion 223c at a relatively static location in relation to a support structure. The first attachment webbing 202 that is coupled to the mid portion 220c of the second energy absorbing webbing 220 pulls the mid portion 220c down with the falling of the safety harness donned by the worker. The first and second energy absorbing webbings 220 and 223 are then pulled apart starting in the respective first tear areas 410a, 440a of the respective first and second sides 210a and 210b of the energy absorbing webbing 210. The tearing or pulling of the fibers 400, 420 to separate the first and second webbings 220 and 223 from each other absorbs energy. If the fall event has not been completed at the end of the respective first tear strength area 410a, 440a, the first and second webbings 220 and 223 begin to separate in the respective transition tear strength areas 410t, 440t. Since, the tear strength is higher in the transition tear strength area, more energy will be absorbed. If the fall event has still not been completed at the end of the transition tear strength areas 410t, 440t, the first and second webbing's 220 and 223 begins to separate in the respective second tear strength area 410b, 440b. Since, the tear strength is even higher in the second tear strength area 410b, 440b even more energy is absorbed. If the fall event is still not completed at the end of the respective second tear strength area 410b, 440b, the first and second energy absorbing webbings 220 and 223 will be totally separated. However, since the back strap portion 206 of the lifeline 104 is also coupled between the first attachment webbing 202 and the second attachment webbing 204 (as illustrated in
Referring to
In this embodiment, a central non-connected area 514 is included. In one embodiment, the first tear strength areas 512a and 512b have a tear strength that is less than the tear strength of the second tear strength areas 510a and 510b. Moreover, the third tear strength areas 512a and 512b that lead to the central non-connected area 514 have a tear strength that is less than the second tear strength areas 510a and 510b. The third tear strength areas 512a and 512b are ramped down sections to the central non-connected area 514. These ramped down sections 512a and 512b prevent instantaneous webbing shock in the first and second webbings 502 and 504 as the webbings 502 and 504 become separated. Webbing shock could damage the overall strength of the strip of webbing 502 and 504. The mid portion 502c and 504c of the first and second webbings 502 and 504 can be folded up or rolled up and positioned in an energy absorbing housing, such as energy absorbing housing 102 shown in
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
This Application claims priority to U.S. Provisional Application Ser. No. 61/552,498 same title herewith, filed on Oct. 28, 2011, which is incorporated in its entirety herein by reference.
Number | Date | Country | |
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61552498 | Oct 2011 | US |