WO2007089196A1

WO2007089196A1 - Spring device for moderating tension

Info

Publication number: WO2007089196A1
Application number: PCT/SE2007/000096
Authority: WO
Inventors: Karl Gustav Derman; Bengt Lindell
Original assignee: SPRING POINT KB
Current assignee: SPRING POINT KB
Priority date: 2005-09-19
Filing date: 2007-02-01
Publication date: 2007-08-09
Anticipated expiration: 2008-08-02
Also published as: NO20054306D0; SE0801878L

Abstract

This invention is designed as a spring device for hauling elements, chiefly intended for ropes when mooring boats. It aims to solve a problem and achieve a practical, muted, and 'weatherproof spring device. Without an extra safety rope, but with controlled elasticity and a continuous rope, it is furthermore suitable for different types of rope, and a straight route through the spring device is created. The invention achieves this through the usage of a sparsely wound spring element (1) with loops (2) that are displaced from the spring's longitudinal axis. To the spring's loops, removable mooring devices (5) are attached that are designed to connect the spring element and absorb tension to the hauling element (6).

Description

Spring device for moderating tension

TECHNICAL AREA:

This invention is designed as a spring device for moderating tension in ropes, cables, chains, or similar elements, and is chiefly designed as a mooring-device for boats.

TECHNICAL STANDPOINT:

Elements that are exposed to tension such as ropes, chains, cables, or leverage rods are often equipped with a spring device for neutralizing the great tension that develops if elements are alternately exposed to powerful pulls and tension release. The alternation between tension and tension relief happens when mooring boats and floating stages due to the movement of the water. If there is no spring in the tension absorbing system the traction can generate such great force that the mooring element, usually a rope or chain, is torn apart or its attachment is loosened.

It is therefore common, and sometimes required, to provide such elements with a spring- device. There are a number of these types of products.

One common spring product consists of a helical spring through which overlapping chains absorb the strain load as compressive force. This type of spiral, however, takes up a considerable amount of space and furthermore has a tendency to create noise. Another disadvantage is that the rope cannot be attached to the element as continuous link, but must be provided with an extra safety detail such as a rope, chain, string, or similar element, outside the element's body. This safety detail creates a continuous link to the mooring rope, so that if the element should break, continuous mooring is ensured. This procedure necessitates that more assembly parts are needed, such as thimbles, shackles, chains, strings, and splices. In addition, the assembly process is time consuming. This extra safety detail is often required by insurance companies in order to ensure that the boat does not tear loose due to breakage of the spring device.

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I SQi ilia 1 O /.1 Another known type of product is a rubber strop. Here, safety is ensured in that the mooring rope is wrapped around the strop and simultaneously fastened to the strop's outer ends. By this means, one makes use of the rubber's elasticity and, through the unbroken link of rope, there is the assurance that the moored entity should not break loose even if the strop itself breaks from exhaustion. This device has its positive aspects, and is small in diameter, however its length is considerable since the rope requires longer revolutions around the strop in order get a sufficiently long elastic motion. It has a relatively high cost, and furthermore it has been shown that, especially in wanner climates, the device has a poorer durability than desired. The aforementioned strop also has the drawback of only being able to be produced in a limited number of sizes.

Another product is described in the patent SE 508 708. Here a tension coil spring is used and acts as a spring function. The spring has two different diameters; a larger diameter at its middle locus where the extra length of rope is situated, and a smaller diameter at its outer ends, which gives a higher spring constant and thus can be used for securing the hauling element. This device has a drawback in that it is pre-stressed, so, upon being stretched and returned to its unloaded position, a banging noise results. This is of great inconvenience when onboard, as it has been shown that the boat functions as a cavity resonator, so even minute sounds are intensified.

The pre-stress discussed also makes the device rigid which results in that the rope placed inside takes a lot longer to dry. Consequently, the rope could get damaged, and there is a risk that it might break. Also, a possible anti-corrosive treatment is made difficult due to the proximity of the coils which is yet another drawback. A limitation of the device is also that only three-strand rope can be used, since the locking device cannot be applied to a braid rope.

Description of the invention

This invention employs a tension coil spring which acts as a spring function, an element which, without elevated costs, can be manufactured by specialty machines. A singular distinctive feature of the invention is exemplified through the execution of the spring; fewer coils eliminate damage due to dampness on the rope. The spring operates quietly and any anti-corrosive treatment can easily be applied round its treads. Nevertheless, its most unique attribute is that the loops on either end are torqued, displaced appropriately above and below the axis that runs laterally as illustrated in Fig. 2.

Brief description of the drawings

Fig. 1 Execution of the spring element.

Fig. 2 The spring element dissected, showing the mooring device's cross-section, assembled on the element, forming the actual spring device, rope, and hypothetical route.

Fig. 3 A top view of the mooring device.

Fig. 4 The mooring device as viewed from behind.

Fig. 5 The spring element, rope, and a magnified cross-sectional view of the mooring device.

Fig. 6 A three-dimensional partial view of the mooring device.

Description of preferred embodiment

In fig.1 the main element of the spring device is shown: (1) a sparsely wound helical spring with terminating end pieces designed in a semi-circle loop and appearing on each side (2) with straight sides (3). The spring element also has a gap (4) between the spring element's body and the spring's end. This gap (4) is not essential for the spring element's (1) function but is designed in order to save on materials.

The thread, of which the spring element (1) is composed , is presumed to be equally thick and is here shown to have a circular cross-section even if other dissections are not disclosed. The material is presumed to be hardened steel, stainless or treated with an anti- corrosive treatment. Alternative materials could be used. The spring element (1) is arranged to function as a tension spring. When exposed to tension the spring will stretch as the coils bend; depending on the so called spring-constant, the stretch will differ according to the tension applied. The value of the spring-constant in turn is pending on the material qualities, the dimension, and diameter of the coils. Thereby, under otherwise similar conditions, the stretch will differ in accordance with the spring's diameter.

Figure 2 and 3 show an embodiment of the mooring device (5). Figure 2 depicts the spring element (1) with the mooring device (5) in cross-section, assembled to the spring element (1) along with a rope (6). The spring element (1) is only shown in part for reasons of space, instead the intended route is shown in detail; its position is at approximately the centre of the spring element (1), due to the fact that the loops (2) are displaced, one in each direction from the centre line, one up and one down. Spring element (1) and mooring device (5) together fashion the spring device intended.

Figure 3 shows mooring device (5) seen from above, showing the body in one piece, which could, if desired, be constructed in separate parts and assembled e.g. by bolts or pegs. Mooring device (5) is appropriately designed as a rectangle with its frontal piece in a semi-circle shape (7) and the body has a greater width than the loop (2) of the spring element (1). The mooring device (5) also has two holes (8) through which the rope (6) is threaded. It could of course have more than two holes. To secure the rope (6) to the mooring device (5) a well-established technique is used where inclining v-shaped grooves (9) are situated in a manner which allows them to counteract one another, thereby the rope nips harder the more tension it is exposed to.

Mooring device (5) is in one piece, and is wider than the spring element's (1) straight side (3) of the loop (2). In order to assemble and disassemble the mooring device (5) to/from the spring element (1) more easily, mooring device (5), viewed from above, depicts a semicircle shaped indention (10) which is carved out towards the axis of the body and occurs on the outer planes. These indentions (10) have the same shape and size as the spring element's (1) thread. When mooring device (5) is attached to the spring element (1) the route will be displaced from the hypothetical centre line of the spring device. To ensure that the spring device (1) does not bend, even tension should be attained at the hypothetical centre line in the spring device. To facilitate a solution to this problem the spring element's (1) loop-formed ends (2) are displaced from the theoretical longitudinal centre line, situated upwards and downwards respectively (Fig.2). Thereby, a route through the spring device is acquired that will roughly meet the centre line in the device. When assembling mooring device (5) to spring element (1), the mooring device (5) is placed in the gap that is created when the loop (2) is torqued, mooring device (5) should then be twisted at about a 45 degree angle in relation to the spring element's (1) longitudinal axis. When the two semicircle indentations (10) are at the middle of the spring element's (1) thread, the mooring device (5) is torqued back so that approximately a 90 degree angle between the details is achieved; the thread will then be situated snugly in the indentions. Thereafter, the top section of mooring device (5) is twisted down towards the spring element's (1) thread until the posterior section (11) of mooring device (5) is attached to the spring element's (1) lower part of the thread. The two protruding anterior parts (12) are resting towards the upper part of the thread.

By means of this construction, the mooring device (5) now has supporting surfaces (14) above and (13) below and the thread is able to absorb tension and compression forces that arise (Fig. 3 and 4). When hauling tension is applied, the spring element's (1) thread aims to stretch since at the loop's terminating end a gap is present between the spring element's (1) body and the loop's end. As previously mentioned, this is in order to save on material but the loop could as well be welded to the spring element's (1) body. To prevent the stretching of the spring element's (1) thread, the posterior indentions (1 1) of mooring device (5) contain outer supporting edges (15). These indentions are suitably shaped after the thread and a protruding lip (16) veers towards the centre line. This lip (16) acts as a fastener, the mooring device (5) clamps around the thread creating a firm connection between the spring element (1) and the mooring device (5). (Fig. 5 and 6)

When tension is applied to the rope (6), seen from the rope's terminating points, the mooring device (5) is pressed downwards from the centre line. In order to absorb the tension forces, mooring device (5) has a groove (17) at the frontal lobe (7) of the semicirclar part where the spring element's (1) loop (2) rests. This groove is fashioned in the likeness of the spring element's (1) thread. In order to ensure that mooring device (5) can also be fitted to other spring devices that are not equipped with the same semicirclar loops (2), the grooves (17) in mooring device (5) are not completely semicircular Fig. 6. Since there is a potential risk that mooring device (5) might slip out of its position in the spring element's (1) loop (2) and shift toward the centre of the spring element (1), the lobe's groove (17) should have one or more protrusions veering towards the centre of the groove. These overhangs or edges can be tear-shaped so that mooring device (5) clamps onto the spring element's u-shaped loop (Fig. 5).

When connecting spring element (1) and mooring device (5) along with rope (6), it is easier if the rope (6) is placed in the mooring device (5) and then attached to spring element (1). The rope (6) is thus threaded through one of the mooring devices (5) then through the spring element (1), and leaving a suitable distance of rope (6) inside the spring element's (1 ) body, the rope is threaded through the second mooring device (5). After connecting the mooring devices (5) to the spring element (1), a continuous link passing through spring element (1) is acquired by the rope (6). Thereby, the spring element can absorb any tension forces that arise.

With a suitable length of extra rope (6) that is located inside the spring element's (1) body, the tension moderator now works. Until a potential force arises that is greater than the spring element's (1) elastic motion, the spring element (1) can not be stretched too far, but should the spring element (1) break, the rope (6) is in one piece and the mooring, of for instance the boat, is ensured.

Claims

1. A spring arrangement for hauling elements such as ropes, comprising at least one spring element (1) in the form of a tension spring, which is designed such that it demonstrates at each of its two end sections a loop-shaped form (2), characterised in that the spring element (1) that acts under the strain load is to be the absorbing spring force for a pre-determined distance of the hauling element (6) and in that the said end sections, when seen along the longitudinal axis of the hauling element, form the loops (2) for holding fixed the attachment elements (5) of the spring arrangement, which are arranged to interact with the spring element (1) in a manner that allows their detachment, and holding fixed the hauling element (6) that passes through.

2. The spring arrangement for hauling elements according to any one of the preceding claims, comprising fixing elements (5) for holding fixed the parts (6) of the hauling element, which fixing elements are arranged to be brought into contact and to function to hold together and support the tension arrangement, characterised in that the fixing elements (5) demonstrate lower (11) and upper (14) supporting surfaces.

3. The spring arrangement according to any one of the preceding claims, that the fixing element (5) has the function that allows it to be applied onto the spring element (1) with a semicircular arc (2) that is not fully formed, characterised in that the groove (17) in the front (7) part of the fixing element (5) is not fully semicircular.

4. The arrangement according to any one of the preceding claims, that the fixing element (5) is arranged such that it can interact with the spring element (1) in a manner that allows it to be removed, characteri sed in that the fixing element (5) demonstrates divided upper (14) and lower (11) parts that constitute supporting surfaces.

5. The arrangement according to any one of the preceding claims, that the fixing element (5) is designed to hold together the loop (2) of the spring element (1), characterised in that the fixing element has outer and inner supporting side surfaces (15) that prevent the fixing element (5) from becoming loose and prevent the loop of the spring element (1) expanding.

6. The arrangement according to any one of the preceding claims, that the fixing element (5) sits firmly in the loop (2) of the spring element (1), characterised in that constrictions (18) (16) in the material of the fixing element (5) are arranged in the forward (17) grooves (11) that lie along the longitudinal sides of the fixing element (5), such that the loop wire of the spring element (1) can be attached by snap-fastening into the fixing element (5).

7. The arrangement according to any one of the preceding claims, characterised in that the limit of strain is formed in that the hauling element (6) such as the form of a rope is locked against withdrawal from the fixing elements (5) and extends uninterrupted between these with such an adapted extra length in addition to the distance between the fixing elements when the spring arrangement is not under load, that the strain is limited to a pre-determined maximum value for the load and for the length of the strain through the extension of the hauling element (6), when the strain corresponds to the said extra length.

8. The arrangement according to any one of the preceding claims, characterised in that the spring arrangement (1) is intended to absorb with its fixing elements (5) sudden jerks in the hauling element (6) with a continuous rope through the spring arrangement (1).

9. The arrangement according to any one of the preceding claims, characterised in that the spring arrangement (1) is arranged with a limit of strain through the pre-determined length of the rope between the fixing elements (5).