US20240352671A1

US20240352671A1 - Fuse assembly having inline trigger for controlled failure and rope systems containing the same

Info

Publication number: US20240352671A1
Application number: US18/642,928
Authority: US
Inventors: Dustin HEINS; James R. Plaia; Chad HISLOP; Anthony KOVICH; John HUGHSON; Michael BOTTERBUSCH; Anu MURTI; Vinh HUYNH; Danielle STENVERS
Original assignee: Samson Rope Technologies Inc
Current assignee: Samson Rope Technologies Inc
Priority date: 2023-04-24
Filing date: 2024-04-23
Publication date: 2024-10-24
Also published as: WO2024224284A1

Abstract

A fuse assembly for rope systems. A catch is a rope segment having a certain failure strength. An accompanying trigger component has a predetermined failure point which can be less than the failure strength of the catch, acting as a sacrificial element to reveal the potential risk of rope recoil. In one embodiment, the catch includes connecting ends, and the trigger is remote from the catch. In other embodiments the trigger includes the connecting ends and the catch is separate from but works cooperatively with the trigger. Additional hold components can accompany the system, as well as first and second chafe protection layers.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of U.S. Provisional Application Ser. No. 63/497,800, filed Apr. 24, 2023, and U.S. Provisional Application Ser. No. 63/509,974, filed Jun. 23, 2023, the entire contents of both of which are incorporated herein by reference.

BACKGROUND

This disclosure is directed to rope fuse assemblies and more particularly to rope fuse assemblies having an inline trigger that provides for controlled failure of a rope system containing the fuse assembly.
Ropes are used in many high-tension applications, including vessel mooring, marine towing, and ground-based towing and vehicle recovery. It is well understood that a mooring line parting event, also referred to as recoil, can pose a significant safety risk. The reason is linked to the fact that any mooring line subjected to tension will stretch. This is readily apparent as a stretched line that is released will pull back in the direction of tension-rapidly. High modulus polyethylene (HMPE) and even steel wire, mooring lines experience a similar if less extreme stretching when subjected to tension. This stretching stores energy within the mooring ropes as the distance between the moving vessel and mooring point increases. If a tensioned line breaks, all of the stretched rope components connected in series are now free to return to their original length and will immediately attempt to do so. This release of stored energy results in the parted ends recoiling away from the break location as the stretched components rapidly relax.
As a result of cumulative damage from external forces from environmental exposure, abrasion and ordinary use, these ropes are subject to potential failure which can lead to recoil having catastrophic results when that failure occurs while the rope is under tension and in use. As such, deterioration must be monitored during routine inspection. Routine inspections, however, do not eliminate the risk of recoil.
There is a need then for rope fuse assemblies, and rope systems that include a fuse assembly, that act as a sacrificial element that fail in a known, controlled way under predetermined conditions, and further, for embodiments which protect these sacrificial elements from abrasion and wear, independent of the rope itself, to further lessen the risk of recoil.

SUMMARY

Comprehended is a fuse assembly, e.g., for rope systems, comprising: a catch having a central portion and at least one catch end, the at least one catch end transitioning from the central portion, the at least one catch end defining a connection point for the fuse assembly, the catch having a failure strength; a trigger, the trigger having a predetermined failure point; and, wherein the trigger is connected to the central portion and thereby remote from the at least one connection point such that solely the catch terminates at the at least one connection point. In one embodiment the trigger is a localized, weak segment of rope generally co-linear with the central portion having its failure point be less than the failure strength of the catch. In another embodiment, the catch includes an extension segment, the extension segment not in tension with the central portion, thereby apart from the trigger when the trigger is in a non-sacrificed state, i.e., the fuse assembly is in an intact state.
It is further comprehended that the trigger includes the connection points rather than the catch transitioning into the connection points. Here, the fuse assembly comprises: a trigger, the trigger having a trigger rope segment and at least one trigger end, the at least one trigger end transitioning from the trigger rope segment to define a connection point for the fuse assembly, the trigger having a predetermined failure point; a catch cooperating with the trigger; and, wherein the trigger is separate from the catch.
It is further comprehended that the fuse assembly includes a third, hold rope component. Here, the fuse assembly comprises: a catch having at least one end, the at least one catch end defining a connection point for the fuse assembly, the catch having a failure strength; a trigger, the trigger having a predetermined failure point, the trigger being separate from the catch and external thereto; and, a hold component, the hold component having a hold strength, the hold strength greater than the predetermined failure point, the hold component having a length greater than both the catch and the trigger such that the hold component is of unequal tension to the catch and the trigger, and wherein upon stretching or failure of both the trigger and the catch, the hold component maintains continuity of the fuse assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary embodiment of the fuse assembly in elevation with the catch being an extension segment.

FIG. 2 a shows an exploded, elevation view of an alternative embodiment of the fuse assembly with the trigger being a spliced-in segment and the catch being a longer loop of rope.

FIG. 2 b shows an elevation view of the similar trigger of FIG. 2 a but with a chafe protection layer.

FIG. 3 shows an elevation view of an alternative embodiment of the fuse assembly with the trigger including a hardware component.

FIG. 4 shows an elevation view of an alternative embodiment of the fuse assembly, largely in schematic form, with the trigger being a slipping splice within a single fabricated structure.

FIG. 5 shows an exploded, elevation view of an alternative embodiment of the fuse assembly including three components.

FIG. 6 shows a perspective view of the instant fuse assembly installed between a mainline and a tail of a rope system extending from a vessel.

FIG. 7 shows a perspective view of the instant fuse assembly installed between a pendant and a mainline of a tug.

FIG. 8 a shows an exploded, elevation view of the instant fuse assembly with a secondary chafe protection layer.

FIG. 8 b shows the same embodiment of FIG. 8 a but in partially assembled, cooperative form.

FIG. 9 a shows a partial perspective view of a fuse assembly main body connected to dock hardware and with the secondary chafe protection at the connection end.

FIG. 9 b shows a perspective view of the fuse assembly of FIG. 8 b in fully-assembled form with all chafe protection layers and connected to dock hardware.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referencing then FIGS. 1-9 b, exemplary embodiments are directed to fuse assemblies 1, and rope systems that include a fuse assembly 1, that act as a sacrificial element that fail in a known, controlled way under predetermined conditions. The fuse assembly 1 has a trigger 6, e.g., an inline trigger 6, designed to fail within a predetermined range of strain energy, as well as a catch 2 that manages energy release upon trigger 6 actuation, thereby providing a controlled failure of the overall rope system that reduces safety hazards, such as recoil, which would be present if the rope system failed without the use of the fuse assembly 1.
Advantageously, exemplary embodiments permit isolation of the trigger 6 from the fuse assembly's connection points 5. As a result, the trigger 6 is less likely to be damaged or fail prematurely as a result of normal use. Additionally, exemplary embodiments provide a wide variation of where the fuse assembly 1 is incorporated into the rope system and does not need to be at the terminal end of a rope system as seen in conventional recoil control solutions.
As noted, the fuse assembly 1 in accordance with exemplary embodiments includes at least a trigger 6 and a catch 2. The trigger 6 establishes a maximum tension that can be applied to the fuse assembly 1, and by extension, to the rope system of which the fuse assembly 1 is a part. The trigger 6 can be any mechanism that provides a predetermined failure point and, in some embodiments, at a predetermined location, and at a predetermined tension, which may be selected based on a particular desired design load and which may depend on the ultimate application. Means by which the predetermined failure point might be determined included, but are not limited to, referencing the working load limit for the rope, or a specified maximum fraction of the system's strength as called out in a relevant industry specification. The ultimate application may include safety and equipment risks that would be incorporated into these maximum tension calculations. Then, the tension for any component can be designed and adjusted to maximize functionality while meeting safety requirements.
With particular reference to FIG. 1 , in some embodiments the fuse assembly 1 includes a catch 2 having a central portion 3 and at least one catch end 4, e.g., two catch ends 4. The catch 2 has a known failure strength. The catch ends 4 transition from the central portion 3 to thereafter terminate and define a connection point 5 for the fuse assembly 1. This connection point 5 allows the fuse assembly 1 to be attached to a rope system or deck hardware 23. At least one connection point 5 allows for integration into the rope system, although typically required would be two connection points 5. The connection points 5 here are shown as eye loops, although not limited thereto. “Rope system” means the ropes themselves or portions thereof, e.g., a pendant 18, mainline 19, tail 20 and/or, depending on the location within the system, for attaching to a mooring bollard or chock or any deck hardware 23 (see FIGS. 9 a, 9 b ). In FIG. 1 , the fuse assembly 1 further includes a trigger component, or trigger 6, provided here as a trigger rope segment 7 spliced at each of its two trigger ends 8, transitioning into central portion 3 of catch 2. In this manner, trigger 6 is a localized, weak segment of rope generally co-linear with the central portion 3, as shown, i.e., sharing a similar central axis to catch 2 although not directly attached to connection points 5.
As further illustrated, the catch 2 includes loops at each end, thereby forming the connection points 5. It will be appreciated that while shown as having two loops, as above, a single loop or even no loops may be employed as the connection points 5 in the catch 2 depending on the manner in which the fuse assembly 1 is connected into the overall rope system. The catch 2 may be a continuous length of synthetic or other rope material in which the loops are formed as spliced eyes or as a cow hitch connection, for example. Note here the trigger 6 is connected to the central portion 3 and thereby remote from the at least one connection point 5, i.e., not directly connected to connection points 5, such that solely the catch 2 terminates at the at least one connection point 5. Such remoteness of the trigger 6 along the catch 2 in this embodiment better ensures integrity of the fuse assembly 1 and may allow for more configurations of the trigger 6 along the catch 2.
The trigger 6 may be a weaker rope with respect to the catch 2 as a result of material selection, diameter, braid angle, or any other characteristic such that the trigger 6 forms the localized weak point of the fuse assembly 1. Alternatively, or in combination, the rope segment forming the trigger 6 may be manufactured with cut strands to induce a localized weak point. It will further be appreciated that the localized weak point may be any predetermined point along the length of the trigger 6 or may be designed to actuate at one of the trigger ends 8 of the trigger 6, for example, by slipping from the splice made with the central portion 3 of the catch 2. In either case, the position of the trigger 6 within the fuse assembly 1 provides a known, predetermined point of failure of the assembly at the location of the trigger 6. In some embodiments, the trigger 6 may be of equal, similar, or even greater strength than the failure strength of the catch 2.
In this embodiment, the catch 2 includes an extension segment 9 that is not in tension during normal operation of the fuse assembly 1 prior to a failure event. Once the trigger 6 is actuated (i.e., breaks), the catch 2 lengthens as the additional length of the extension segment 9 is taken up and pulls taut, and holds, at least temporarily, continuity of the rope system in which the fuse assembly 1 is used. Of note is that being the extension segment 9 is not in tension with the central portion 3 of catch 2, the extension segment 9 is thereby “apart”, i.e., un-connected and separate from the trigger 6 when the trigger 6 is in a non-sacrificed state, i.e., the fuse assembly 1 is in a non-reactive or intact state.
With particular reference to FIG. 2 a , shown is an embodiment wherein, instead of the catch 2 terminating to form the connection points 5, here the trigger 6 has at least one trigger end 8 which transition into the connection points 5. The trigger 6 has a trigger rope segment 7 and at least one trigger end 8. The trigger end 8 transitions from the trigger rope segment 7 to define a connection point 5 for the fuse assembly 1. As above, the trigger 6 has a predetermined failure point. FIG. 2 a is largely schematic showing the catch 2 exaggeratedly surrounding trigger 6. The catch 2 here cooperates with the trigger 6, thus the trigger 6 is separate from the catch 2. “Cooperates” means the trigger 6 travels around the catch 2 partially in an x-y plane and abuts, intertwines centrally or otherwise works with the catch and does not necessarily cylindrically and entirely envelope the trigger 6 as would a tubular jacket. See FIG. 2 b , for example. As above, the catch 2 has a failure strength which can be greater than the predetermined failure point of the trigger 6, although not required.
Again, FIG. 2 a is largely schematic in that it shows the catch 2 separate and exploded from the trigger 6 although the two would be abutting each other or at least cooperatively arranged. It further illustrates the fuse assembly 1 in which the trigger 6 is a continuous rope segment having spliced eye loops as the connection points 5, with the trigger 6 including a localized weak segment 21 in which that portion of the trigger 6 can been braided or twisted to a different degree and/or having cut strands and which is isolated from connection points 5 that, along with the catch 2, provide the connection points 5 for attachment of the fuse assembly 1 into the greater rope system.
As shown in this embodiment, the catch 2 is a separate rope component, shown here as a loop that extends the length of the fuse assembly 1. The loop that forms the catch 2 may be constructed by splicing one end of a continuous rope segment to an opposing end of that same segment. While the catch 2 and trigger 6 are cooperatively arranged to form the fuse assembly 1, unlike the embodiment described in FIG. 1 , the catch 2 is not physically spliced or otherwise directly connected to the trigger 6.
In some embodiments, the catch 2 is not in tension prior to failure of the trigger 6. In other embodiments, the catch 2 may be sized so that both the trigger 6 and the catch 2 are simultaneously in tension during normal operation, but the trigger 6 is formed of a rope having a lower elongation of failure. Upon trigger 6 activation, the catch 2 remains in tension, absorbing the additional strain through elongation as a result of its higher elasticity/elongation to failure.
As above, it will be appreciated that the catch 2 is shown in an exaggerated manner to better illustrate the catch 2 as a continuous loop (such as splicing a continuous rope segment back onto itself), but that in operation, extended portions of the loop would ordinarily be collapsed to be in close proximity to the trigger 6 as seen in the inset of FIG. 2 b . Therefore, in combination, at least a main body 17 of the fuse assembly 1 may include both the trigger 6 and catch 2, for example, contained within a chafe 14 to give the outward appearance of a singular device, while the resulting ends of the catch 2 provide partial loops that, in conjunction with the trigger loops, provide connection points 5 for the fuse assembly 1 with the rope system. It will further be appreciated that the loops/connection points 5 of trigger 6 and catch 2 may also be contained within a chafe 14, 15 to provide a more uniform appearance and to facilitate use.
FIG. 3 schematically illustrates a fuse assembly 1 that has a trigger 6 that is a piece of hardware, termed herein rigid hardware component 10. “Rigid” means of a flexibility other than that of rope, being a semi-rigid, substantially rigid or completely rigid material component, such as a plastic or metal bar. Rigid hardware component 10 includes at least one hardware connection location 11 and may further include one or more weak points 12. The weak point 12 is shown here as a notch 12 defined therein, generally medially, but the weak point 12 can be any weakening attribute causing the rigid hardware component to, by design, pre-maturely break, such as a longer slit, perforation, shape modification or the like. The catch 2 is looped through, e.g., a hole, or otherwise connected directly to the trigger 6 at hardware connection location 11. In another embodiment, the catch 2 is in tension from the connection points 5 to the loop on each side of the trigger 6. In another embodiment, the catch 2 has separate eyelets within the extension segment 9, as shown. As tension is applied to the fuse assembly 1 during operation, the ends of the trigger 6 are pulled away from one another at the hardware connection location 11. The trigger 6 begins to fail from the weak point 12, as the tension exceeds the yield strength of the rigid hardware component 10. When the tension exceeds the ultimate force, the rigid hardware component 10 breaks and the trigger 6 is actuated. The strain is absorbed by the catch 2 via the extension segment 9 in a manner similar to that described with respect to FIG. 1 . “A” as used in the claims, especially as it relates to this embodiment, means one or more.
FIG. 4 schematically illustrates a fuse assembly 1 in which the trigger 6 and catch 2 are part of a single fabricated structure. This figure is schematic to exaggeratively depict slipping splice 13, although the slipping splice 13 does not consist of separated segments. Here, the catch 2 is constructed of two different continuous rope segments that are spliced into one continuous length, each segment having a spliced eye loop at one end forming the at least one connection point 5. The opposite ends of the rope segments extend to be co-linear with one another and are spliced with a slipping splice 13 such that the slipping splice 13 forms the trigger 6. Note the trigger 6 is still remote from the (at least one) connection point 5 because the connection point 5 transitions from the rope segments of the catch 2. At a predetermined tension, the trigger 6 is activated as the slipping splice 13 begins to slip, thus gradually. As a result, the two rope segments pull away from one another, absorbing the strain through work as the catch 2 length gradually grows from point a to b. At a second predetermined tension, the slipping splice 13 is under enough compression that the two rope segments no longer slip past one another and instead are held in a fixed relationship to one another. Accordingly, the two segments slip and thereby increase in length without complete failure of the slipping splice 13.
FIG. 5 schematically illustrates a fuse assembly 50, according to yet another exemplary embodiment, here in an exploded view, using a separate hold component 16. A trigger 6 is formed of a continuous rope segment having preferably two spliced eye loops forming trigger end 8 and which is designed to fail at a predetermined tension or failure point, all in a manner as previously described. A catch 2 is also formed of a continuous rope segment, also having two spliced eye loops forming catch end 4. In this embodiment, the catch 2 is provided having a same length as the trigger 6 but external thereto, so the two are simultaneously in tension, but in which the catch 2 might have a higher elongation to failure than the trigger 6. “External” means the trigger 6 is not contained within any jacket of the catch 2 but is separate, yet abutting or otherwise working cooperatively therewith, similar to FIG. 2 a . Upon failure of the trigger 6, the catch 2 stretches, resulting in work that absorbs strain energy.
In this embodiment, a hold component 16 is provided as a third continuous rope segment and also having spliced eye loops. Although schematically depicted as being of generally equal length to the catch 2, the hold component 16 would preferably be longer in length than both the trigger 6 and the catch 2. In the preferred embodiment, the hold component 16 has a hold strength which is greater than both the failure strength (of the catch 2) and the predetermined failure point (of the trigger 6). All components would work cooperatively and be intertwined (similar to FIG. 2 b ). The hold component 16 maintains continuity and retains full system strength even after trigger activation and provides stability in the event of a failure of the catch 2, which may be intentional to the design of the fuse assembly 1 or as a backstop for an additional safety measure in the event of an unanticipated failure of the catch 2.
Fuse assemblies, in accordance with exemplary embodiments, can be used in a wide variety of rope systems and advantageously can be used in such systems for mooring and tug/marine towing applications that include a mainline and a terminal rope, such as a tail and/or pendant.
That said, FIG. 6 illustrates a rope system in a mooring application that includes a mainline 19 extending from a vessel, a fuse assembly 1, and a tail 20, each in series. Moreover, the various rope components of the rope system may further include hardware elements as part of their connection to one another. In some embodiments, the fuse assembly 1 may be integrated directly into the terminal end of the tail 20 or even the mainline 19, although the sacrificial and thus disposable nature of the fuse assembly 1 is such that, in many cases, it may be desirable to provide the fuse assembly 1 as a separate component so that the other components of the rope system may remain in service after replacement of a new fuse assembly 1.
As further illustrated in FIG. 6 , the fuse assembly 1 is shown as a separate component of the rope system and is positioned intermediate the mainline 19 and the tail 20, the tail 20 being a terminal rope. One of the advantages of exemplary embodiments is the ability to support multiple different configurations in which the fuse assembly 1 may be installed at any location along the rope system. Advantageously, this allows the fuse assembly 1 to be positioned away from cleats, bollards and other hardware used on the dock and/or the vessel that are high contact/high wear locations that may increase the likelihood of damage and/or premature actuation of the trigger. The fuse assembly 1 is designed for the trigger 6 to actuate at a predetermined tension that is less than the maximum safe tension of the tail 20, mainline 19 other terminal rope component along the rope system that might fail, even when damaged. However, actuation of the trigger 6 at less than its design load, such as may occur from weakening from excess handling of the fuse assembly 1, is also undesirable. Exemplary embodiments give greater control over positioning of the fuse assembly 1, and thus more reliable operation.
FIG. 7 illustrates a rope system in a tug application in which a fuse assembly 1 is located in series intermediate a pendant 18, i.e., the terminal rope in this particular application, attached to a vessel under tow and a mainline 19 extending from a tug. As illustrated, the fuse assembly 1 is shown as an individual element of the rope system, although it could, for example, be integrated into the proximal end of the pendant 18 where the pendant 18 couples to the mainline 19.
FIGS. 8 a through 9 b schematically illustrate an exemplary embodiment similar to that described earlier with respect to FIGS. 2 a and 2 b but which further highlight chafe protection layers 14, 15.
As described earlier, the catch 2 is constructed from a material having a low modulus and high elongation. It will be appreciated that such low modulus, high elongation materials for use in forming the catch 2 may include undrawn or substantially undrawn fibers, such as, for example, those described in U.S. Pat. No. 8,365,646, which is incorporated herein by reference.
In embodiments incorporating such fibers, or in the aforementioned embodiments, it may be desirable to enclose the entirety of the fuse assembly 1 within a chafe or first chafe protection layer 14 (See FIG. 9 b ) over main body 17 (here exposed in FIG. 9 a ). Moreover, the ends of the fuse assembly 1 that provide connection points 5 to deck hardware 23 via the partial catch loops and trigger loops tend to be subject to heightened handling and stress, such as when connected to another rope via a cow hitch or similar connection. In order to better protect the fibers of the catch 2 from crush effects as a result of those end connections, some presently preferred embodiments employ one or more additional layers of chafe protection, termed herein secondary chafe protection layer 15 wrapped around the ends of the catch 2 under the typically more expansive first chafe protection layer 14 that covers the entire assembly (see FIG. 8 a , meant only to detail this secondary layer 15 and at connection point 5). As a result, the connection points 5 formed by the catch 2 have at least two layers of protection 14, 15 (FIG. 9 b ), which reduces crushing or other damage from handling that may have a tendency to induce some elongation of the undrawn fibers in those regions of the catch 2 and which could, in turn, result in decreasing the amount of elongation available to the catch 2 during operation.
FIG. 9 b therefore provides an example of a reduction to practice of the embodiment described with respect to FIGS. 8 a through 9 a in a more assembled view and as would be used in the field.
In summary, components of the trigger 6 may include, for example, a rope segment, a hardware element, or even a slipping splice, all by way of example. The trigger 6 is constructed so that if a predetermined maximum acceptable tension for the rope system is exceeded, the trigger fails in a preplanned fashion and location within the rope system.
Once the trigger 6 has acted to limit the tension applied to the rope(s) as a result of the failure, the catch acts to contain or absorb the remaining strain energy within the rope system, helping prevent recoil as a result of the trigger's actuation.
It may be advantageous for the fuse assembly 1 to retain sufficient strength to permit continuity of the overall rope system. This function may also be accomplished by the catch 2, although it will be appreciated that in some cases, the separate hold component 16 may be provided to perform that function, particularly if the catch 2 is also designed to fail as part of containing the excess strain energy. For example, in some embodiments, it is contemplated that multiple trigger 6, catch 2 and/or hold components 16 be employed, permitting the fuse assembly 1 to actuate at one tension, catch, actuate at a second tension, catch, and so on until an ultimate hold component 16 remains intact.
As for material, the trigger 6 of the fuse assembly 1 may be composed of one or more ropes, subcomponents of a rope, other fiber-based fabricated structures, such as fiber chain, and/or hardware. The trigger's activation mechanism may be accomplished through the choice of material, such as a particular synthetic composition used in forming one or more strands of a rope trigger and/or from intentional cuts or reduced strand counts formed in a localized area. Other examples of trigger mechanisms that may be employed include a rope, or fabricated structure using rope, in which a short length of the rope is braided or twisted differently than the rest of the trigger element to create a designated location of weakness along the length of the trigger component. In other embodiments, the trigger component may be designed to fail at a splice location, such as where one or more ends of the trigger is spliced with the catch. In still other embodiments, the trigger component may be a hardware device, for example, of a metal or polymer material, that is fabricated to fail as the material's yield strength is exceeded and break at a predetermined tension that exceeds the material's ultimate strength. For example, a clevis pin or shackle bolt may be machined with a notch in the tensioning region such that failure of the pin or bolt is the trigger actuation. It will be appreciated that regardless of the specific mechanism of trigger actuation, the trigger 6 is positioned within the fuse assembly 1 so that the failure location of the trigger 6 is remote and thereby isolated from the fuse assembly's connection points 5 to other elements of the rope system.
In each case, the trigger 6 is designed such that it actuates at a pre-determined tension to prevent application of tension exceeding that limit, providing an engineered weak point for the overall rope system. As such, the trigger 6 component (as well as the fuse assembly 1 of which it is a part) can intentionally be positioned within the rope system such that the location of a failure in the rope system is also pre-determined.
It will be appreciated that the trigger 6 may also be designed so that the connection points 5 to the overall rope system do not affect the actuation tension of the trigger 6. That is, the trigger 6 may be constructed such that the triggering tension is not affected by bends, twists, or connection methods used to connect the fuse structure to the overall rope system. This may be accomplished such that trigger activation happens at a force lower than a calculated strength which accounts for strength deductions resulting from bends, twists, or connection methods. One approach, for example, is to require the fuse assembly-to-overall rope system connection to be through shackles or similar hardware to ensure a bend radius of the trigger does not cause an unanticipated localized weak location.
As to the aforementioned catch 2, the catch 2 may be composed of one or more ropes, subcomponents of a rope, or other fiber-based fabricated structures, such as fiber chain. The catch 2 is constructed to absorb or contain strain energy released when the trigger actuates, limiting application of tension on the overall system. As shown, the catch 2 may accomplish this function by having an extended length segment that was not in tension prior to trigger actuation but comes into tension as a result of that actuation, and/or the catch being constructed of a material that undergoes high elongation prior to failure.
The extended length of the catch 2, whether through initial fabrication or through high elongation, permits the catch 2 to extend, and thus the length of the fuse assembly 1 to grow, thereby absorbing released strain energy by converting the strain energy released into work performed (i.e., force moving through distance). The energy may also be absorbed by controlled failure of the catch or portions of the catch wherein each portion requires a known amount of energy to fail and thereby absorbs the released strain energy.
The catch 2 may also contain strain energy through the use of an extended length. In some embodiments, that length may be wrapped around or twisted around the fuse component such that it is free to deploy when the trigger is activated. The catch 2 may also act to contain strain energy through the use of a splice having a predetermined amount of slippage. This slipping splice 13 can either gain in strength and hold after the known slippage, thus incorporating the function of the hold component 16, or completely slip out and transfer tension to the separate hold component 16.
In still other embodiments, the catch 2 may be a rope or fabricated structure using a rope that has a compressible core. When the catch 2 is actuated, increasing tension on the catch leads the rope to compress this core, thus absorbing strain energy through core compression and realignment of catch rope subcomponents in response to the smaller diameter core.
It will also be appreciated the catch 2 may be composed of a rope or fabricated structure using rope that has a higher elongation at failure than the trigger 6 component rope(s). When the trigger 6 and catch 2 are loaded in parallel, the trigger fails at a strain below the failure elongation of the catch 2 and the remaining elongation of the catch 2 is used to absorb the released strain energy.
As already described, the catch 2 may serve to hold the rope system in place in addition to absorbing the released strain energy, or a separate hold component 16 may be used, for example, in situations in which the catch 2 absorbs strain energy through successive failure. If a separate hold component 16 is employed, as above, the hold component 16 may be composed of one or more ropes, subcomponents of a rope, or other fiber-based fabricated structures, such as fiber chain. The hold component 16 provides ultimate residual strength of the fuse assembly 1 after the trigger(s) and catch(es) actuate for maintaining continuity of the overall rope system into which the fuse assembly 1 is incorporated.
As above, to protect the trigger 6 and catch 2 from damage during normal use, protection may be employed, such as, for example, braided covers over the catch 2, or adding an additional safety factor in sizing the nominal strength of the hold component to account for anticipated damage and resulting loss of strength.
Additional materials of construction of the ropes used as components within the fuse assemblies 1 described herein may be of the same or similar type as used in other types of synthetic rope manufacture, although the particular materials used in any specific instance may vary and will depend, for example, on which component of the fuse assembly the material will be used and the type of fuse assembly constructions employed. Exemplary suitable materials include poly (ethylene terephthalate), polyethylene (especially high molecular weight and ultrahigh molecular weight polyethylene, also known as high modulus polyethylene), polypropylene, polyamides, such as nylon, and aromatic polyamides, such as those available under the tradenames Technora®, Kevlar®, and Twaron®, all by way of example.
High modulus fibers may be used in creating the trigger 6, while low modulus, high elongation at failure fibers may be used for the catch 2. The rope used as the trigger 6 may be modified in a local area, such as through a precalculated number of cut strands in a specific circumferential pattern, to ensure the break location and tension is not affected by the connection between the trigger component and the overall rope system. It will be appreciated that the fuse assemblies 1 described herein may be engineered for the size of the load under which they are expected to operate. Thus, for example, the diameter of the trigger rope is selected to achieve the correct fuse actuation tension in the cut strand location, while the diameter and length of the catch is ordinarily determined through calculation based on the strain energy the catch is designed to absorb.
Various exemplary fuse assemblies are schematically illustrated and described. Although rope segments may be shown with various shapes, textures and/or as a singular line for simplicity, it will be appreciated that all of the rope and rope segments described herein could be one or more strands of natural or (preferably) synthetic fiber braided to form a yarn and may further constitute multiple such yarns, in which the yarns themselves are braided with one another. For example, in some embodiments, one or more of the rope components may be a braided twelve-strand rope. In other embodiments, for example, a braided three-strand or seven-strand rope may be used as one or more of the components of the fuse assembly.
While the invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention but that the invention will include all embodiments falling within the scope of the appended claims. In addition, all numerical values identified in the detailed description shall be interpreted as though the precise and approximate values are both expressly identified.

Claims

What is claimed is:

1. A fuse assembly, comprising:

a catch having a central portion and at least one catch end, said at least one catch end transitioning from said central portion, said at least one catch end defining a connection point for said fuse assembly, said catch having a failure strength;

a trigger, said trigger having a predetermined failure point, and,

wherein said trigger is connected to said central portion and thereby remote from said at least one connection point such that solely said catch terminates at said at least one connection point.

2. The fuse assembly of claim 1, wherein said predetermined failure point is less than said failure strength of said catch.

3. The fuse assembly of claim 1, wherein said trigger is a localized, weak segment of rope generally co-linear with said central portion.

4. The fuse assembly of claim 3, wherein said catch includes an extension segment, said extension segment not in tension with said central portion, thereby said extension segment is apart from said trigger when said trigger is in a non-sacrificed state.

5. The fuse assembly of claim 1, wherein said trigger is a rigid hardware component.

6. The fuse assembly of claim 5, wherein said rigid hardware component further comprises:

at least one hardware connection location wherein said rigid hardware component can be connected to said central portion; and, a weak point defined within said rigid hardware component.

7. The fuse assembly of claim 6, wherein said weak point is a notch defined medially within said rigid hardware component.

8. The fuse assembly of claim 1, wherein said catch and said trigger are a single, fabricated structure, said trigger formed as a slipping splice within said catch, said slipping splice transitioning into said central portion of said catch such that said catch is adapted to elongate upon said failure strength exceeding said predetermined failure point.

9. The fuse assembly of claim 1, further comprising a first chafe protection layer over said fuse assembly.

10. The fuse assembly of claim 1, further comprising a secondary chafe protection layer over said at least one connection point.

11. A fuse assembly, comprising:

a trigger, said trigger having a trigger rope segment and at least one trigger end, said at least one trigger end transitioning from said trigger rope segment to define a connection point for said fuse assembly, said trigger having a predetermined failure point;

a catch separate from said trigger but working cooperatively therewith, said catch having a failure strength; and,

wherein said trigger is separate from said catch.

12. The fuse assembly of claim 11 wherein said trigger includes a localized, weak segment of rope, said localized, weak segment of rope connected to said trigger rope segment and thereby remote from said at least one trigger end.

13. The fuse assembly of claim 11, further comprising a first chafe protection layer over said fuse assembly.

14. The fuse assembly of claim 11, further comprising a secondary chafe protection layer over said connection point.

15. A fuse assembly, comprising:

a catch having at least one catch end, said at least one catch end defining a connection point for said fuse assembly, said catch having a failure strength;

a trigger, said trigger having a predetermined failure point, said trigger being separate from said catch and external thereto working cooperatively therewith; and,

a hold component, said hold component having a hold strength, said hold strength greater than both said failure strength and said predetermined failure strength, said hold component having a length greater than both said catch and said trigger such that said hold component is of unequal tension to said catch and said trigger, and wherein upon stretching or failure of both said trigger and said catch, said hold component maintains continuity of said fuse assembly.

16. The fuse assembly of claim 15, further comprising a first chafe protection layer over said fuse assembly.

17. The fuse assembly of claim 15, further comprising a secondary chafe protection layer over said connection point.

18. A rope system comprising:

a mainline;

a terminal rope;

a fuse assembly, said fuse assembly further comprising: a catch having a central portion and at least one catch end, said at least one catch end transitioning from said central portion, said at least one catch end defining a connection point for said fuse assembly, said catch having a failure strength;

a trigger, said trigger having a predetermined failure point;

wherein said fuse assembly is connected in series with, and intermediate, said mainline and said terminal rope.

19. The fuse assembly of claim 18, further comprising a first chafe protection layer over said fuse assembly.

20. The fuse assembly of claim 18, further comprising a secondary chafe protection layer over said connection point.