BACKGROUND OF THE INVENTION

The invention relates to an anchor having a fluke for digging in the anchor into an anchoring ground and a shank for coupling the fluke to an object to be anchored.

In a known anchor having a fluke and a shank the shank is provided with two shank legs that are coupled to the fluke. The coupling of the shank legs to the fluke is subjected to very large forces during digging in the anchor into the anchoring ground. In order to absorb these forces the shank legs have a reinforced construction. Said construction is heavy and adversely affects the penetration behaviour of the anchor.

It is an object of the invention to provide an anchor having a fluke and a shank that has improved penetration behaviour.

SUMMARY OF THE INVENTION

The invention provides an anchor having a fluke for in a penetration direction digging in the anchor into an anchoring ground and a shank coupled to the fluke for coupling the fluke to an object to be anchored, wherein the fluke has a fluke main plane, wherein the shank comprises a first shank leg, a second shank leg and a third shank leg, wherein in a direction transverse to the penetration direction spaced apart from each other the first shank leg and the second shank leg are coupled to the fluke by a first hinge and a second hinge, respectively, wherein the third shank leg is coupled to the fluke between the first shank leg and the second shank leg by a third hinge.

By distributing the forces that arise at the location of the coupling between the shank and the fluke over three shank legs, the shank can be constructed more lightweight whereas the stability and the loadability of the anchor remains ensured or can even be improved. Ensuring stability, the advantageous transfer of forces and the reduced weight can result in the anchor according to the invention showing more favourable penetration behaviour during digging in into the anchoring ground. Particularly the results in relation to the built-up resistance at repetitively digging in the anchor into an anchoring ground can show a less wide range than the known anchors do, as a result of which the accuracy in predicting the penetration behaviour and the reliability of the obtained anchoring can be increased.

In one embodiment the hinges have a common rotary centre line. The shank is able to rotate about the common rotary centre line.

In one embodiment the shank is rotatable, with respect to the fluke, about the common rotary centre line between a first end position and a second position, wherein in the first end position the shank is diagonally upright with respect to the fluke main plane, wherein in the second position the shank is situated in the same plane as the fluke main plane. In the first end position the anchor is able to dig in into the anchoring ground. In the second position the anchor can be stored in a compact manner.

In one embodiment the first shank leg and the second shank leg are coupled to the fluke at the outer sides of the fluke main plane that are situated transverse to the penetration direction. The distance between the first shank leg and the second shank leg can increase the stability of the anchor during digging in. By placing the first shank leg and the second shank leg at the outer side of the fluke main plane an as large as possible intermediate distance can be achieved .

In one embodiment the first hinge and the second hinge each comprise a hinge plate situated inside relative to the fluke main plane and a hinge plate situated outside relative to the fluke main plane, wherein the first shank leg and the second shank leg extend between the hinge plates of the first hinge and the second hinge, respectively. The plate situated outside can shield the couplings between the shank legs and the fluke on the outside of the fluke. The plates situated outside can counteract that possible obstacles the anchor encounters in penetration direction during digging in, adversely affect the operation of the anchor .

In one embodiment, at the location of the coupling to the hinges, the first shank leg and the second shank leg are provided with end ears that are directed towards the hinges. In that way the shank legs are able to connect at right angles to the hinges.

In one embodiment the fluke is provided with wedge parts extending spaced apart from the fluke main plane above and/or below the fluke main plane. The wedge parts form a wedge above and below the fluke main plane for at an inclined angle supporting the fluke main plane on the anchoring ground. In that way it can be effected that - when the anchor is lowered onto the anchoring ground - the anchor will at all times penetrate the anchoring ground at an initially downward angle .

In one embodiment, in the transverse direction relative to the penetration direction, the wedge parts extend over the full width of the fluke main plane. The wedge parts are able to support the anchor over the full width, so that the anchor will come to be at an angle to the anchoring ground on irregular surfaces as well .

In one embodiment, at the outer sides situated transverse to the penetration direction, the wedge parts merge into or are attached to the first hinge and the second hinge. The wedge parts are able to strengthen the connection between the three shank legs and effect an advantageous transfer of forces between the three shank legs and the fluke.

In one embodiment the wedge parts form a rigid unity with the first hinge and the second hinge. The wedge parts are able to strengthen the connection between the three shank legs and effect an advantageous transfer of forces between the three shank legs and the fluke .

In one embodiment the wedge parts jointly define a quadrangular cross-section that is symmetrical with respect to the fluke main plane. In that way the wing plates are able to direct the direction of the anchor during digging in into the anchoring ground.

In one embodiment the wedge parts are wing plates, the main planes of which are at an inclined angle to the fluke main plane. As a result the wing plates can form a wedge above and below the fluke main plane for supporting the fluke main plane on the anchoring ground at an inclined angle. In that way it can be effected that - when the anchor is lowered onto the anchoring ground - the anchor will at all times penetrate the anchoring ground at an initially downward angle .

In one embodiment the main planes of the wing plates converge towards a point of convergence, wherein relative to the penetration direction the point of convergence is situated behind the leading penetration tip of the fluke main plane. The wing plates are capable of influencing the penetration behaviour of the anchor in the anchoring ground.

In one embodiment the shank legs are coupled to each other spaced apart from the couplings of the shank legs to the fluke. In that way the first shank leg and the second shank leg can contribute to the stability of the third shank leg relative to the shank.

In one embodiment the shank legs form a rigid unity. As a result the shank legs can move as one unity.

In one embodiment, in cross-section transverse to the longitudinal direction, the third shank leg has a larger surface area than the first shank leg and/or the second shank leg have in that cross-section. As a result the third shank leg is capable of bearing the largest part of the fluke weight and able to absorb most of the forces thereof.

In one embodiment the third shank leg comprises a stop surface that in the rotary direction from the second position to the first end position comes to lie in abutment with the fluke and blocks a rotation of the shank beyond the first end position. In that way the third shank leg is able to limit the maximum range over which the shank and its three shank legs are able to rotate relative to the fluke main plane .

In one embodiment the stop surface limits the rotation of the shank to an angle relative to the fluke main plane of approximately thirty to thirty-five degrees, preferably approximately thirty-two degrees. Said angle may be suitable for penetrating sand or hard clay .

In an alternative embodiment the stop surface limits the rotation of the shank to an angle relative to the fluke main plane of approximately forty-five to fifty-five degrees, preferably approximately fifty degrees. Said angle may be suitable for penetrating soft clay. In one embodiment the third shank leg comprises an end ear for attaching an anchor line to the object to be anchored. In that way the shank is able to operationally form the coupling between the fluke and the object to be anchored.

In one embodiment the fluke is provided with two fluke plates extending in the fluke main plane with in between them an accommodation space for in the second position accommodating the third shank leg between the fluke plates. Because the third shank leg can be accommodated between the fluke plates the shank can come to lie fully flat or flush in the plane of the fluke main plane.

In one embodiment, in the second position, the first shank leg and the second shank leg extend beyond the fluke main plane. In that way the first shank leg and the second shank leg in the second position do not contact the fluke main plane of the fluke, as a result of which the shank is able to flip through past the fluke main plane to the other side of the fluke main plane .

In one embodiment the fluke main plane has the shape of a kite, preferably having two equal long sides and two equal short sides. The kite shape has an acute leading section that can be used for penetrating the anchoring ground.

In one embodiment, in the second position, the first shank leg and the second shank leg extend along the long sides of the fluke main plane. In that way the shank is able to flip past the fluke to the other side of the fluke main plane.

In one embodiment the third shank leg is situated in the vertical plane of symmetry of the fluke main plane extending in the longitudinal direction. As a result the shank leg can rotate through the middle of the fluke. The aspects and measures described in this description and the claims of the application and/or shown in the drawings of this application may where possible also be used individually. Said individual aspects may be the subject of divisional patent applications relating thereto. This particularly applies to the measures and aspects that are described per se in the sub claims.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of a number of exemplary embodiments shown in the attached schematic drawings, in which:

Figure 1 shows an isometric front view of an anchor having a fluke and a shank that is diagonally upright from the fluke, according to an embodiment of the invention;

Figure 2 shows an isometric rear view of the anchor according to figure 1;

Figure 3 shows an isometric front view of the anchor according to figure 1, wherein the shank is situated flat relative to the fluke; and

Figures 4, 5 and 6 show a side view, a front view and a top view, respectively, of the anchor according to figure 1.

DETAILED DESCRIPTION OF THE DRAWINGS

Figures 1-6 show an anchor 1 according to an embodiment of the invention, particularly an anchor 1 for the offshore, for instance having a deadweight of at least one thousand kilos. The anchor 1 is adapted for in a dig-in direction or penetration direction P digging into or penetrating an anchoring ground, in order to anchor a vessel or an object to be anchored, such as an oil platform, attached to the anchor 1 in the anchoring ground. The anchor 1 comprises a fluke 2 and a shank 5 coupled to the fluke so as to hinge, which shank is described in more detail below.

As shown in figures 1 and 2, the fluke 2 comprises a straight fluke main plane 20 having a quadrangular, kite-shaped main contour defined by two equal long sides 21 and two equal short sides 22. The fluke 2 has a longitudinal centre line L and a transverse direction B. The fluke main plane 20 can notionally be divided into an acute wedge-shaped front section 23 extending in the penetration direction P of the anchor 1 and an obtuse rear section 24 extending in the opposite direction. The fluke 2 comprises a first fluke plate 25 and a second fluke plate 26 extending in the fluke main plane 20 and that on either side of the longitudinal centre line L divide the fluke 2 into two mirror-symmetrical halves. The fluke plates 25, 26 are situated spaced apart from the longitudinal centre line L and in the front section 23 of the fluke 2 form two individual, leading penetration tips 27, 28 oriented in the penetration direction P.

As shown in figures 1-6 the fluke 2 is provided with a reinforcement sleeve 30 extending parallel to the longitudinal centre line L centrally through the fluke 2 and connecting the spaced apart fluke plates 25, 26 to each other. The reinforcement sleeve 30 comprises parallel to each other, a first reinforcement plate 31 and a second reinforcement plate 32 extending transverse to the fluke plates 25, 26 and connecting to the first fluke plate 25 and the second fluke pate 26, respectively. In the rear section 24 of the fluke 2 the reinforcement plates 31, 32 are connected to each other by an upper plate 33 and a lower plate 34. Above and below the fluke plates 25, 26, the reinforcement plates 31, 32 are designed substantially mirror-symmetrical relative to the fluke main plane 20 and converge, just like the fluke plates 25, 26 in the penetration direction P into penetration tips 27, 28. In the front section 23 of the fluke 2, the reinforcement plates 31, 32 bound an accommodation space H between the fluke plates 25, 26 for accommodating the shank 5 and allowing it to pass through in a manner to be further described.

As shown in figure 6, considered in transverse direction B, on the largest width of the fluke main plane 20, at the sides of the kite shape where the long sides 21 and the short sides 22 of the fluke main plane 20 come together, the fluke 2 is provided with a first hinge 41 and a second hinge 42, respectively. The first hinge 41 and the second hinge 42 are each formed by hinge plate or eye plate 44 situated outside relative to the fluke main plane 20 and a hinge plate or eye plate 45 situated inside relative to the fluke main plane 20 that together form a hinge plate pair or eye plate pair. The eye plates 44 situated outside are designed extra heavy and shield the internal parts of the first hinge 41 and the second hinge 42 on the outside of the fluke 2, so that it can be counteracted that possible obstacles the anchor 1 encounters during digging in in the penetration direction P adversely affect the operation of the anchor 1. The reinforcement plates 31, 32 of the reinforcement sleeve 30 have also been provided with eyes 35 that form a third hinge 43. The eyes 35 are situated in one line or coaxially with respect to the eyes in the eye plates 44, 45. The rotary centre lines of the hinges 41-43 thus coincide and define a joint rotary centre line R.

As shown in figures 1 and 2, at the location of the rear section 24, the fluke 2 is furthermore provided with wedge parts in the form of two first spoilers or wing plates 36, 37 and two second wing plates 38, 39. The first wing plates 36, 37 extend transverse to the longitudinal direction L on either side above and below the first fluke plate 25 and spaced apart from the fluke main plane 20, from the upper plate 33 and the lower plate 34, respectively, of the reinforcement sleeve 30 to the eye plate 44, situated outside, of the first hinge 41 and at that location merge into the eye plate 44 situated outside. The distance between the wing plates 36, 37, 38, 39 and the fluke plates 25, 26 defines passages 40 for allowing soil material, such as sand and mud, to pass through opposite the penetration direction P. The second wing plates 38, 39 extend transverse to the longitudinal direction L on either side above and below the second fluke plate 26 from the upper plate 33 and the lower plate 34, respectively, of the reinforcement sleeve 30 to the eye plate 44, situated outside, of the second hinge 42 and at that location merge into the eye plate 44 situated outside. As shown in figure 4 the wing plates 36-39 are at a steep angle with which they notionally converge in the penetration direction P into a tip. The point of convergence of the wing plates 36- 39 is situated in the fluke main plane 20 behind the penetration tips 27, 28. As shown in front view in figure 5, the wing plates 36-39 define a substantially diamond-shaped cross-section of the fluke 2.

The wing plates 36-39 form a wedge above and below the fluke main plane 20 for at an inclined angle supporting the fluke main plane 20 on the anchoring ground. In that way it can be effected that - when the anchor 1 is lowered onto the anchoring ground - the penetration tips 27, 28 will at all times penetrate the anchoring ground at an initially downward angle.

As shown in figures 1, 2 and 3 the shank 5 is provided with a straight first shank leg 51, a straight second shank leg 52 and a straight third shank leg 53. Considered in transverse direction B, the first shank leg 51 and the second shank leg 52, are coupled to the first hinge 41 and the second hinge 42, respectively, on the outer sides of the shank main plane 20. The third shank leg 53 extends between the first shank leg 51 and the second shank leg 52 in the vertical plane of symmetry extending at the location of the longitudinal centre line L. The third shank leg 53 is coupled to the third hinge 43.

Each shank leg 51-53 is provided with a first end ear 54 that is fittingly accommodated between the attachment plates 31, 32 or eye plates 44, 45 of the related hinges 41-43 and is coupled to the eyes of the related hinges 41-43 by means of a pin 55. The end ears 54 of the first shank leg 51 and the second shank leg 52 are directed towards the first hinge 41 and the second hinge 42, respectively, in order extend at right angles between them. The couplings between the first end ears 54 and the hinges 41-43 allow a rotation of the shank 5 relative to the fluke main plane 20 of the fluke 2 about the rotary centre line R.

In figure 1 the shank 5 is shown in a first end position wherein the shank 5 extends at the upper side of the fluke main plane 20 at an angle of approximately thirty-two degrees to the fluke main plane 20. Said angle is suitable for penetrating sand or hard clay. In figure 3 the shank 5 is shown in a second position wherein the shank 5 extends at an angle of zero degrees to the fluke main plane 20. In the second position the shank legs 51-53 are situated in the same plane as the fluke main plane 20, wherein the third shank leg 53 is accommodated in the accommodation space H between the fluke plates 25, 26. The fluke plates 25, 26 are situated within the contour of the first shank leg 51 and the second shank leg 52. In a third end position, not shown, the shank 5 is situated at the lower side of the fluke main plane 20, at an angle of approximately thirty-two degrees to the fluke main plane 20. Such a situation may arise when the anchor 1 ends up upside down on the anchoring ground. In the third end position the anchor 1 operates in the same manner as in the first end position. The following description of the figures therefore is restricted to describing the functionality of the anchor 1 in relation to the first end position.

As can be seen in figure 3 the third shank leg 53 is provided with a stop block 56 having a stop surface 57 that is adapted for in the first end position of the shank 5 contacting or butting the upper plate 33 of the reinforcement sleeve 30 or an extension thereof. At the lower side of the fluke main plane 20 the stop block 56 is also provided with a stop surface that is hidden from view, for in the same manner providing abutment between the third shank leg 53 and the lower plate 34 of the reinforcement sleeve 30. By means of the design or the position of the stop block 56 the maximum rotary range of the shank 5 above and below the fluke main plane 20 can therefore be defined. In an alternative embodiment the stop surface 57 permits the shank to rotate up to a maximum angle of fifty degrees to the fluke main plane 20 of the fluke 2, which angle is suitable for penetrating soft clay.

As shown in figures 1 and 4, at the outer end facing away from the rear section 24 of the fluke 2, the third shank leg 53 is provided with a second end ear 58 to which for instance a pin of a bow shackle that is not shown is attached. The bow shackle forms an attachment for a shackle of a chain or anchor line that is not shown leading to the vessel or the object to be anchored .

As shown in figures 2 and 5, considered from the rear section 24 of the fluke 2, the shank legs 51- 53 converge towards each other and together with the rotary centre line R form a triangle. The first shank leg 51 and the second shank leg 52 are fixedly connected to the third shank leg 53 and together with the third shank leg 53 form a rigid three-legged suspension for the fluke 2. The shank legs 51-53 are able to move as one unity about the rotary centre line R between the first diagonally upright position and the second position that is situated in the plane of the fluke 2. Of the three shank legs 51-53 the first shank leg 51 and the second shank leg 52 increase the stability of the fluke 2 relative to the central third shank leg 53, for instance in a situation in which the fluke 2 is loaded with a transverse component during digging in into the anchoring ground. In the manner described above the central third shank leg 53 defines the maximum range over which the shank 5 and its three shank legs 51-53 are able to rotate relative to the fluke main plane 20. The third shank leg 53 moreover bears the largest part of the weight of the fluke 2 and absorbs most of its forces. The third shank leg 53 therefore is designed heavier and/or stronger, or has a larger surface area in cross-section than the first shank leg 51 and the second shank leg 52 have.

By distributing the forces arising at the location of the coupling between the shank 5 and the fluke 2 over three shank legs 51-53, the shank 5 can be constructed more lightweight, for instance by designing the first shank leg 51 and the second shank leg 52 more lightweight than the third shank leg 53, whereas the stability and the loadability of the anchor 1 remains ensured. The wing plates 36-39 strengthen the relation between the hinges 41-43, the fluke plates 25, 26 and the reinforcement sleeve 30, as a result of which a stiff or rigid construction is obtained and an advantageous transfer of forces can be realised between the three shank legs 51-53 and the fluke 2.

Due to the increased stability, the advantageous transfer of forces and the reduced weight the anchor 1 according to the embodiment described above of the invention shows favourable penetration behaviour when it penetrates the anchoring ground. Particularly the results in relation to the built-up resistance at repetitively digging in the anchor 1 into an anchoring ground shows a less wide range than known anchors do, as a result of which the accuracy in predicting the penetration behaviour and the reliability of the obtained anchoring can be increased.

The above description is included to illustrate the operation of preferred embodiments of the invention and not to limit the scope of the invention. Starting from the above explanation many variations that fall within the spirit and scope of the present invention will be evident to an expert.