GB2127935A - Two stage elastomeric shock absorbing arrangement for a marine structure - Google Patents

Abstract

A closed end cylinder 18 is axially aligned within an elongate hollow body 11 and projects therefrom, with the diameter of the cylinder being less than that of the hollow body to provide an annular space A therebetween. An elastomer body 15 is provided in the annular space A and is moulded to the hollow body 11 and cylinder 18, the elastomer body 15 including an enlargement 40 thereon projecting from the end of the elastomer body adjacent the closed cylinder end 26, which enlargement is of a different, that is a higher, durometer than the durometer of that portion of the elastomer body in the annular space. Stop means 50 are secured in the hollow body 11 in spaced relation to the enlargement 40 for engagement therewith. The elastomer body 15 contains voids. <IMAGE>

Description

SPECIFICATION Two stage shock absorbing arrangement for a marine structure My prior issued United States Patent No.

3,995,437 illustrates a device for use with marine structures to serve as a shock absorbing arrangement when barges, boats or other marine vessels engage such structures. Such device functions quite satisfactorily, but in some situations does not readily react to various size marine vessels.

It can be appreciated that vessels of varying capacity and tonnage approach and contact marine structures. Some vessels are substantially large, while others may be relatively small. In some instances, certain portions of marine structures may be designated for receiving a certain type of craft or vessel which may be generally uniform in size so that throughout the period of use of a shock absorbing arrangement at such locations, the loading thereof may be generally uniform throughout its normal life span.

However, in other situations, it may be desirable to provide or use shock absorbing arrangements which move quite readily to react to vessels to absorb the inital shock, and which thereafter react to rapidly and progressively become more resistant to flex to absorb the continuing impact of larger vessels or to absorb substantially initally harder or greater impacts. Also, present shock cells do not readily flex to properly dampen and absorb impacts from smaller vessels.

Therefore, an object of the present invention is to provide a two stage shock absorbing arrangement for a marine structure which will handle or absorb smaller impacts initially and upon continued movement become more resistant to further movement to absorb greater impacts.

Yet a further object of the present invention is to provide a two stage shock absorbing arrangement for a marine structure which will absorb the softer blows normally associated with smaller vessels as well as larger blows or impacts normally associated with larger vessels.

Other objects and advantages of the present invention will become more readily apparent from a consideration of the following description and drawings.

Figure 1 is a partial elevational view showing a portion of a structure leg of an offshore or marine structure with a bumper guard secured thereto and with the shock absorbing arrangement of the present invention positioned between the bumper guard and the structure leg; Figure 2 is a sectional view on the line 2-2 of Fig. 1 illustrating the preferred configuration and arrangement of the device of the present invention incorporating a hollow body, a cylinder axially aligned therewith and projecting from an end of the body with an elastomer body positioned between the hollow body and the cylinder; stop means are secured in the hollow body for engagement with the elastomer body; Figure 3 is a sectional view on the line 3-3 of Fig. 1 illustrating further sectional details of the stop means; Figure 4 is a sectional view on the line 4-4 of Fig. 1 illustrating circumferential recesses or voids in the elastomer body in the annular space between the hollow body and the cylinder; and Figure 5 is a sectional view on the line 5-5 of Fig. 1 partly in elevation and showing in further detail the enlargement on the elastomer body.

Attention is first directed to Fig. 1 of the drawings wherein a portion of a structure leg of an offshore structure or marine structure is represented generally by the numeral 4. It can be appreciated that the lower end of such leg is positioned in the earth in a water covered area with the upper leg end terminating above the water covered area to serve as a suitable support for a deck or platform in the water covered area. It can be further appreciated that a plurality of such legs is provided to accomplish such purpose.

A bumper guard is illustrated generally by the numeral 5 and is shown as extending generally in a vertical direction which serves as a protection to inhibit damage to the structure leg 4, or to a marine vessel, as such vessel approaches the offshore structure. The lower end of the bumper guard 5 is supported by any suitable arrangement generally illustrated at 7 and the presented invention referred to generally at 10 is positioned adjacent the upper end of the bumper guard between the structure leg 4 and the bumper guard. It can be appreciated that the support 7 accommodates movement of the lower end of the bumper guard 5 as the present invention functions to accommodate movement of the bumper guard relative to the support leg 4 when the bumper guard 5 is engaged by a vessel as will be described.

As more clearly seen in Fig. 2, the present invention 10 includes an elongated hollow body 11 having ends 1 2 and 1 3 thereon. The end 1 3 is suitably configured in a manner well known in the art to be received and secured on the jacket leg 4 as illustrated in Fig. 1. It can be further appreciated that the present invention 10 is fabricated before it is positioned on the jacket leg 4.

A cylinder 1 8 is axially aligned within the hollow body 11 adjacent the end 1 2 thereof and projects from the end 1 2 of the hollow body 11 as shown in the drawings. The diameter of the cylinder 1 3 is less than the diameter of the hollow body 11 to provide an annular space referred to by A between the hollow body 11 and the cylinder 1 8. The closed end 26 of the cylinder 1 8 is positioned within the hollow body 11 as illustrated.An annular elastomer body referred to generally at 1 5 is molded to the hollow body 11 and cylinder 1 8 and extends longitudinally within the annular space A adjacent the end 1 2 of the hollow body 11 so as to encase and enclose the cylinder 1 8 therein and secure the elastomer body 15, hollow body 11 and cylinder 1 8 together.

As noted above, the elastomer body 1 5 encases or encloses the cylinder 18 including the closed cylinder end 26 and further includes an enlargement 40 which projects in the direction from the closed end 26 of the cylinder 1 8 as shown in the drawings. Stop means referred to generally by the numeral 50 are positioned in the hollow body 11 in spaced relation to the end 41 of the enlargement 40 as shown. Such stop means are shown as being in the form of a circular disk or flat plate 51 carried on support 52 and 53, which supports are secured in the hollow body 11 by any suitable means such as welds 54 or the like.

The portion of the elastomer body 1 5 in the annular space A between the hollow body 11 and cylinder 1 8 is provided with a plurality of circumferentially spaced voids 21 molded therein having an open end 22 facing in the same direction as the open end 1 7 of cylinder 18. The other end 24 of the voids 21 is spaced from the adjacent end portion 26' of the elastomer body 1 5 shown.

It can be appreciated that the open end 1 7 of the cylinder 1 8 is suitably configured in a manner well known in the art so as to be secured to the support 5A of the bumper guard 5. The enlargement 40 presents a substantial mass of elastomer and includes an annular recess 42 as shown, with the end 41 thereof presenting a flat surface for contact with the flat plate 51 as will be described.

The portion of the elastomer body 1 5 extending longitudinally in the annular space A is of a different durometer than the durometer of the elastomer body portion forming the enlargement 40. More specifically, the portion of the elastomer body 1 5 in the annular space A and in which the cylinder 1 8 is encased as illustrated in the drawings is of a durometer so that it is more flexible and softer and will respond or react to lower or smaller impacts imparted thereto by vessels upon contact with the bumper guard 5. On the other hand, the enlargement 40 is formed of an elastomer having a different durometer so that it is harder and less likely to flex. From the foregoing, it is seen that the durometer body 1 5 in the annular space A is less than the durometer of the enlargement 40.

This arrangement provides a two stage shock absorbing arrangement in that it will function to accommodate and react to smaller vessels which engage the bumper guard 5 as well as larger vessels which engage the bumper guard 5. For example, when an initial contact is made against the bumper guard 5, the elastomer body portion 1 5 in the annular space A between the hollow body 11 and cylinder 1 8 being more flexible will respond, even if such impact is relatively small. Such impact, of course, causes the cylinder 1 8 and the elastomer 1 5 to move longitudinally of the hollow body 11 so as to engage the end 41 of the enlargement 40 with the plate 50.

Since the enlargement 40 is formed of a different or higher durometer elastomer, the resistance to further compression and movement of the enlargement 40 when it contacts the plate 50 is substantial so that in a rapid and progressive manner, the resistance to movement by the present arrangement increases and dampens and absorbs the continuing impact against the bumper guard 5 applied thereto by a vessel.

Stated differently, when a vessel contacts the bumper guard 5, the present invention will react to dampen and abosrb the shock regardless of the impact. For example, if a smaller vessel engages the bumper guard, the lower durometer portion of the elastomer body 1 5 reacts and resiliently responds. If the impact from a larger vessel upon engaging the bumper guard 5 is sufficient to move the enlargement 40 into contact with stop means 50, there is substantially immediate reaction since the enlargement 40 is of harder elastomer and the resistance to compression is rapid so as to dampen the impact and absorb the load.

Thus, the present invention provides a shock absorbing arrangement which will respond and absorb shocks and dampen loads imparted to the bumper guard 5 and hence to the structure leg 4 by smaller vessels, and will also accomplish the same function when larger vessels contact the bumper guard 5.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated contruction may be made without departing from the spirit of the invention.

Claims (4)

1. A shock absorbing arrangement for marine structures comprising: a. an annular elongated hollow body; b. a cylinder axially aligned within said hollow body adjacent an end thereof to project therefrom; c. said cylinder having a smaller diameter than said hollow body to provide an annular space therebetween and having a closed end positioned within said hollow body; d. a body of elastomer molded in the annular space between said body and said cylin der; e. said elastomer body having a plurality of circumferentially spaced, longitudinally extending voids therein; ; f. said elastomer body including an enlargement thereon, said enlargement projecting from the end of said elastomer body adjacent the closed end of said cylinder, and said enlargement being formed of a different durometer than that portion of said elastomer body in the annular space between said hollow body and cylinder; and g. stop means secured in said hollow body in spaced relation to said enlargement.

2. The arrangement of claim 1 wherein said elastomer body in the annular space is of a lower durometer than the durometer of said enlargement.

3. The arrangement of claim 1 wherein said enlargement is cylindrical, is axially aligned with said cylinder and includes a central recess.

4. A shock absorbing arrangement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.