Marine knuckle boom crane

Abstract

A marine knuckle boom crane includes a crane housing which is rotational relative to a pedestal about a vertical rotation axis and a knuckle boom assembly attached to the crane housing. The knuckle boom assembly includes a main boom, the inner end of which is connected pivotably about a first horizontal pivot axis to the crane housing; and a jib, the inner end of which is connected pivotably about a second horizontal pivot axis to the outer end of the main boom, wherein the jib is pivotable at least between an extended position in which the tip extends mainly forward from the main boom, and a folded position in which the jib is folded back, essentially parallel along the main boom. In order to position the jib with respect to the main boom, a tensioning member is provided extending between the crane housing and a curved extension guide connected to the jib.

Claims

1. A marine knuckle boom crane comprising: a stationary pedestal to be mounted to or formed integral with a vessel; a crane housing having an upper portion, a central portion and a lower portion, the crane housing being rotational relative to the pedestal about a vertical rotation axis; and a knuckle boom assembly attached to the crane housing, the knuckle boom assembly comprising: a main boom comprising an inner end, a central area and an outer end, the inner end of the main boom being connected pivotably about a first horizontal pivot axis to a lower portion of the crane housing; a jib comprising an inner end, a central area and a tip opposite the inner end of the jib, the inner end of the jib being connected pivotably about a second horizontal pivot axis to the outer end of the main boom, wherein the jib is pivotable at least between an extended position in which the tip extends mainly forward from the main boom, and a folded position in which the jib is folded back, with the tip of the jib being brought to be close to a middle portion of the main boom; a tensioning member and a curved extension guide for positioning the jib with respect to the main boom, the tensioning member extending between the crane housing and the curved extension guide, wherein the tensioning member comprises: a first portion comprising at least two articulated interconnected elongated rods; and a second portion comprising sheaves and a cable, a length of the cable being variable, one of the at least two articulated interconnected elongated rods being connected to the second portion via a first pivot point, the at least two articulated interconnected elongated rods being interconnected via a second pivot point, and wherein the curved extension guide is mounted to the jib, pivotable together with the jib about the second pivot axis, and comprises: three spokes including a first spoke, a second spoke and a third spoke, each having a distal end; a connecting beam extending from the third spoke to the tip of the jib, wherein the tensioning member is connected to the third spoke, and the first and second pivot points of the tensioning member are adapted to coincide with the distal ends of the first and second spokes of the curved extension guide, respectively, and wherein: when the jib is in the folded position, the first portion of the tensioning member is guided by the curved extension guide, and the first and second pivot points of the tensioning member coincide with the distal ends of the first and second spokes of the curved extension guide, respectively, when the jib is in the extended position, the first pivot point is spaced apart from the distal end of the first spoke by a distance, with the distal end of the first spoke being a free end, and the second pivot point is spaced apart from the distal end of the second spoke by a distance, with the distal end of the second spoke being a free end, and when the jib is in an intermediate position between the folded position and the extended position, the first pivot point is spaced apart from the distal end of the first spoke by a distance, with the distal end of the first spoke being a free end, and the second pivot point coincides with the distal end of the second spoke; a tensioning winch configured to vary the length of the cable of the tensioning member and thus to position the jib; a luffing cable for positioning the main boom, extending between the outer end of the main boom and the upper portion of the crane housing; and a luffing winch configured to vary the length of the luffing cable and thus to position the main boom.

2. The marine knuckle boom crane according to claim 1, wherein a yang is provided between the main boom and the jib to position and/or fixate the position of the jib with respect to the main boom.

3. The marine knuckle boom crane according to claim 2, wherein the tensioning member extends between the lower portion of the crane housing and the curved extension guide.

4. The marine knuckle boom crane according to claim 2, wherein the tensioning member extends between the central portion of the crane housing and the curved extension guide.

5. The marine knuckle boom crane according to claim 2, wherein the tensioning member extends between the upper portion of the crane housing and the curved extension guide.

6. The marine knuckle boom crane according to claim 2, wherein the tensioning member comprises a first portion being guided by the curved extension guide and a second portion of which the length may be varied by the tensioning winch.

7. The marine knuckle boom crane according to claim 2, further comprising a hoist assembly, comprising a hoist winch and a hoisting cable, extending from the hoist winch via sheaves over the tip of the jib to a load suspension device.

8. The marine knuckle boom crane according to claim 1, wherein the tensioning member extends between the lower portion of the crane housing and the curved extension guide.

9. The marine knuckle boom crane according to claim 8, wherein the tensioning member comprises a first portion being guided by the curved extension guide and a second portion of which the length may be varied by the tensioning winch.

10. The marine knuckle boom crane according to claim 8, further comprising a hoist assembly, comprising a hoist winch and a hoisting cable, extending from the hoist winch via sheaves over the tip of the jib to a load suspension device.

11. The marine knuckle boom crane according to claim 1, wherein the tensioning member extends between the central portion of the crane housing and the curved extension guide.

12. The marine knuckle boom crane according to claim 11, wherein the length of the cable of the second portion is varied by the tensioning winch.

13. The marine knuckle boom crane according to claim 11, further comprising a hoist assembly, comprising a hoist winch and a hoisting cable, extending from the hoist winch via sheaves over the tip of the jib to a load suspension device.

14. The marine knuckle boom crane according to claim 1, wherein the tensioning member extends between the upper portion of the crane housing and the curved extension guide.

15. The marine knuckle boom crane according to claim 14, wherein the tensioning member comprises a first portion being guided by the curved extension guide and a second portion of which the length may be varied by the tensioning winch.

16. The marine knuckle boom crane according to claim 14, further comprising a hoist assembly, comprising a hoist winch and a hoisting cable, extending from the hoist winch via sheaves over the tip of the jib to a load suspension device.

17. The marine knuckle boom crane according to claim 1, wherein the length of the cable of the second portion is varied by the tensioning winch.

18. The marine knuckle boom crane according to claim 17, further comprising a hoist assembly, comprising a hoist winch and a hoisting cable, extending from the hoist winch via sheaves over the tip of the jib to a load suspension device.

19. The marine knuckle boom crane according to claim 1, further comprising a hoist assembly, comprising a hoist winch and a hoisting cable, extending from the hoist winch via sheaves over the tip of the jib to a load suspension device.

20. A marine knuckle boom crane comprising: a stationary pedestal to be mounted to or formed integral with a vessel; a crane housing having an upper portion, a central portion and a lower portion, the crane housing being rotational relative to the pedestal about a vertical rotation axis; and a knuckle boom assembly attached to the crane housing, the knuckle boom assembly comprising: a main boom comprising an inner end, a central area and an outer end, the inner end of the main boom being connected pivotably about a first horizontal pivot axis to a lower portion of the crane housing; a jib comprising an inner end, a central area and a tip opposite the inner end of the jib, the inner end of the jib being connected pivotably about a second horizontal pivot axis to the outer end of the main boom, wherein the jib is pivotable at least between an extended position in which the tip extends mainly forward from the main boom, and a folded position in which the jib is folded back, with the tip of the jib being brought to be close to a middle portion of the main boom; a tensioning member and a curved extension guide, for positioning the jib with respect to the main boom, the tensioning member extending between the crane housing and the curved extension guide, wherein the tensioning member comprises: a first portion comprising at least two articulated interconnected elongated rods; and a second portion comprising sheaves and a cable, a length of the cable being variable, one of the at least two articulated interconnected elongated rods being connected to the second portion via a first pivot point, the at least two articulated interconnected elongated rods being interconnected via a second pivot point, wherein a distal sheave of the second portion is directly connected to the one of the at least two articulated interconnected elongated rods, and wherein the curved extension guide is mounted to the jib, pivotable together with the jib about the second pivot axis, and comprises: three spokes including a first spoke, a second spoke and a third spoke, each having a distal end; a connecting beam extending from a third spoke to the tip of the jib, wherein the tensioning member is connected to the third spoke, and wherein the first and second pivot points of the tensioning member are adapted to coincide with the distal ends of the first and second spokes of the curved extension guide, respectively and wherein: when the jib is in the folded position, the first portion of the tensioning member is guided by the curved extension guide, and the first and second pivot points of the tensioning member coincide with the distal ends of the first and second spokes of the curved extension guide, respectively, when the jib is in the extended position, the first pivot point is spaced apart from the distal end of the first spoke by a distance, with the distal end of the first spoke being a free end, and the second pivot point is spaced apart from the distal end of the second spoke by a distance, with the distal end of the second spoke being a free end, and when the jib is in an intermediate position between the folded position and the extended position, the first pivot point is spaced apart from the distal end of the first spoke by a distance, with the distal end of the first spoke being a free end, and the second pivot point coincides with the distal end of the second spoke; a tensioning winch configured to vary the length of the cable of the tensioning member and thus to position the jib; a luffing cable for positioning the main boom, extending between the outer end of the main boom and the upper portion of the crane housing; and a luffing winch configured to vary the length of the luffing cable and thus to position the main boom.

Description

(1) The invention is further elucidated in the attached drawings, in which:

(2) FIG. 1 shows a schematical side view of a first embodiment of a marine knuckle boom crane according to the present invention;

(3) FIG. 2 shows a schematical side view of a second embodiment of a marine knuckle boom crane according to the present invention in a first position;

(4) FIG. 3 shows a schematical side view of the second embodiment of a marine knuckle boom crane according to the present invention in a second position;

(5) FIG. 4 shows a schematical side view of the second embodiment of a marine knuckle boom crane according to the present invention in a third position;

(6) FIG. 5 shows a schematical side view of the second embodiment of a marine knuckle boom crane according to the present invention in a fourth position;

(7) FIGS. 6a-6c show a schematical side view of a third embodiment of a marine knuckle boom crane according to the present invention in various positions.

(8) In FIG. 1 a marine knuckle boom crane 1 according to the invention is schematically shown. The marine knuckle boom crane 1 comprises a stationary pedestal 9, which in the shown embodiment is mounted to the deck 2 of a vessel (not shown). A crane housing 3, 15 is provided rotational relative to the pedestal 9 about a vertical rotation axis R. The crane housing of this embodiment comprises a base portion 3, having a cross section essentially similar to that of the pedestal 9, and an elongated portion 15 extending essentially upwards from the base portion, defining an upper portion of the crane housing.

(9) Attached to a lower portion of the crane housing 3 is the inner end of a main boom 4, which is connected pivotably about a first horizontal pivot axis 20 to the crane housing 3, 15. A jib 5 is connected pivotably about a second horizontal pivot axis 21 to the outer end of the main boom 4.

(10) A hoist assembly is provided, comprising a hoist winch 8 which is in the shown embodiment provided below deck 2, below the pedestal 9, in the hull of the vessel (not shown). The hoist winch 8 of the shown embodiment can be translated to a position shown in dotted lines. Possibly, the hoist winch is skiddable via a mechanism described in our co-pending application having priority number NL1039735. From the hoist winch 8 a hoisting cable 6a, 6b, 6c extends, which extends via sheaves 23, 21s, 22 over the jib to a load suspension device 7. The pivot axis of sheave 21s coincides with pivot axis 21. Sheave 22 on the jib is defined as the departing sheave 22.

(11) In order to position the main boom 4, a luffing device 12 is provided, extending between the outer end of the main boom 4, here in particular in the vicinity of the second pivot axis 21, and the crane housing, here an upper point 28 of the upper portion 15 of the crane housing. The luffing device preferably comprises a luffing winch 31 and a luffing cable.

(12) In order to position the jib 5 with respect to the main boom 4, a tensioning member 11a, 11b is provided, extending between the crane housing and a curved extension guide 10. In the shown embodiment the tensioning member is connected to the upper portion 15, in particular to a sheave 24 provided in the central area of the upper portion 15. It is also conceivable that the tensioning member 11a, 11b is attached to the lower end of the upper portion, or directly to the lower portion of the crane house 3.

(13) The shown tensioning member 11a, 11b comprises a combination of cables and sheaves 11b, which can be actuated via a tensioning winch 32 to vary in length. The tensioning member further comprises a cable 11a, a portion of which is guided along the outer contour of the curved extension guide 10. The curved extension guide 10 is connected to the jib 5, here near the inner end of the jib 5, and is pivotable together with the jib 5 about the second pivot axis 21. The extension guide 10 of the shown embodiment comprises three spokes 10a, interconnected by a guide 10b defining a curvature approximating a portion of a circle about the second pivot axis 21. Cable 11a is guided along this guide 10b.

(14) In FIGS. 2-5 a second embodiment of a knuckle boom crane 100 according to the invention is shown. Similar to the embodiment of FIG. 1, the marine knuckle boom crane comprises a stationary pedestal 109, mounted to the deck 102 of a vessel, not shown. A crane housing 103 is provided rotational relative to the pedestal 109 about a vertical rotation axis 108. To this end, a horizontal rotational bearing is provided between the pedestal 109 and the crane housing 103. In the shown embodiment, a platform 109′ is connected to the pedestal 109. The crane housing is provided with an operator's housing 103′.

(15) The crane housing 103 comprises an elongated portion 115. In the shown embodiment the elongated portion is shaped as a closed vertical column tapering towards the top. The central axis of the elongated portion extends at an angle of about 20° with respect to the vertical, to give room to the main boom 104.

(16) The knuckle boom assembly comprises a main boom 104 and a jib 105. The main boom 104 comprises an inner end 104a, a central area 104b and an outer end 104c. The main boom 104 is connected at its inner end 104a pivotably to the lower portion of the crane housing 103, rotatable about a first horizontal pivot axis 114.

(17) A jib 105 is provided, comprising an inner end 105a, a central area 105b and a tip 105c opposite the inner end 105a of the jib. The inner end 105a of the jib is connected pivotably about a second pivot horizontal axis 116 to the outer end 104c of the main boom.

(18) The knuckle boom crane of this embodiment further comprises a hoist assembly to hoist and lower loads. The hoist assembly comprises a hoisting cable 106, only part of which is visible in FIGS. 2-5. The hoisting cable 106 extends from a hoist winch (not visible but similar to hoist winch 8 shown in FIG. 1), which is preferably positioned in or below the pedestal of the crane, via one or more sheaves, in particular a sheave 122 at the tip 105c of the jib to a load suspension device 107.

(19) In order to position the jib 105 with respect to the main boom 104, according to the invention a tensioning member 111a, 111b and a curved extension guide 110 are provided. The tensioning member 111a, 111b extends between the upper portion 115 of the crane housing 103 and the curved extension guide 110. In the shown embodiment, the tensioning member 111a, 111b is connected to a central area 115b of the upper portion 115. It is also conceivable that the tensioning member 111a, 111b is connected to a lower end of the upper portion 115, or to the foot of the crane housing 103. It is possible, but less preferred in view of the interplay of forces, that the tensioning member 111a, 111b is connected to the upper end of the upper portion 115.

(20) In the shown embodiment, the tensioning member 111a, 111b comprises a first portion 111a being guided by the curved extension guide 110 and a second portion 111b of the which the length may be varied by the tensioning winch, and as such position the jib.

(21) The curved extension guide 110 is in this embodiment, contrary to the embodiment shown in FIG. 1, of a more oval, not rounded structure. It comprises a bent portion 110d, mounted to various spokes 110a, which extend from a hub 110b. The spokes 110a may vary in length, as in the embodiment of FIG. 2. The mutual dimensions of the spokes can vary from embodiment to embodiment, and be adjusted to the desired curvature of the curved guide member which is dependent from the overall dimensions of the marine knuckle boom crane.

(22) In this embodiment, the curved extension guide 110 is mounted to the jib 105 via a connecting beam 110c, extending from an end of the bent portion 110d to the tip of the jib 105c. The curved extension guide 110 is pivotable together with the jib 105 about the second pivot axis 116, to which also hub 110b is mounted.

(23) In the shown embodiment, first portion 111a of the tensioning member is being guided by the curved extension guide 110 and extends from the second portion 111b to the top of the curved extension guide 110 to a connection point 110e.

(24) The combination of tensioning member 111a, 111b and a curved extension guide 110 enables an accurate control of the position of the jib 105 at a range of different positions with respect to the main boom 104: from an extended position in which the tip 105c extends mainly forward from the main boom, as visible in FIGS. 2 and 4, to a folded position in which the jib is folded back, essentially parallel along the main boom, as is visible in FIGS. 3 and 5.

(25) In order to position the main boom, a luffing cable 112 is provided, extending between the main boom and the crane housing. The luffing cable is preferably connected to the outer end of the main boom, in particular to a sheave connected to the outer end of the main boom, or advantageously to a sheave rotatable about the second pivot axis 116 as in the shown embodiment.

(26) The luffing cable 112 extends to the crane housing 103, which may theoretically be a lower portion of the crane housing 103 close to the pedestal 109. In order to allow the main boom to extend in a vertical direction, it is preferred for the luffing cable to be connected to a portion of the crane housing remote from the location where the main boom is connected to the crane housing. In the shown embodiment, the main boom 104 is rotatably connected to the crane housing about pivot axis 114. The luffing cable 112 is connected to the upper end of the elongated portion 115, being as remote as possible from the main boom connection point. As such, a variety of positions of the main boom is possible: from an almost vertical position as shown in FIGS. 2 and 3, to an almost horizontal position as shown in FIGS. 4 and 5.

(27) Advantageaously, a vang 120 is provided between the main boom and the jib. In the shown embodiment, the vang is embodied as a cable which can be actuated by a winch, which is not shown. Alternatively, the vang can be embodied as a cylinder, but this may cause restrictions in use in terms of stroke.

(28) The vang 120 is connected to the main boom, here to the central area 104b of the main boom, and to the jib. It is conceivable that the vang is connected to the central area 105b of the jib, or to the tip of the jib 105c as in the shown embodiment.

(29) In FIGS. 2 and 4, the vang is at its maximum length, allowing the knuckle boom to be in its extended position in which the tip 105c extends mainly forward from the main boom. In FIGS. 3 and 5, the vang 120 is shown at its minimum length, being fully retracted. This allows the knuckle boom to be in its folded position in which the jib 105 is folded back, essentially parallel along the main boom 104.

(30) The function of the vang in the positions shown in FIGS. 2-4 is to fixate the position of the jib 105, in particular, to prevent an upward movement of the jib. In particular in the position shown in FIG. 4, due to sea-state induced vessel motions it is possible for the main boom and the jib to be lifted up slightly. This is prevented by gravity, not only exerted on the main boom and the jib but also to a load which may be suspended from the crane assembly. The vang 120 further contributes to the prevention of undesired lifting up movements.

(31) In FIG. 5, the vang 120 is shown at its minimum length, allowing the knuckle boom to be in its folded position in which the jib 105 is folded back, essentially parallel along the main boom 104. The function of the vang in this position is to position the jib 105 in the folded position, as the combination of tensioning member 111a, 111b and curved guide assembly 110 is capable of positioning the jib with respect to the main boom into the positions shown in FIGS. 2-4, but not to the position shown in FIG. 5. To arrive at this position, the vang 120 has to be actuated to bring and maintain the jib 105 to this retracted position.

(32) In FIGS. 6a-6c a third embodiment of a knuckle boom crane 200 according to the invention is shown. Similar to the embodiment of FIG. 1, the marine knuckle boom crane comprises a stationary pedestal 209, mounted to the deck 202 of a vessel 201. A crane housing 203 is provided rotational relative to the pedestal 209 about a vertical rotation axis. To this end, a horizontal rotational bearing is provided between the pedestal 209 and the crane housing 203. In the shown embodiment, a platform 209′ is connected to the pedestal 209. The crane housing is provided with an operator's housing 203′.

(33) The crane housing 203 comprises an elongated portion 215. In the shown embodiment the elongated portion is shaped as a closed vertical column tapering towards the top. The central axis of the vertical elongated portion extends at an angle of about 20° with respect to the vertical, to give room to the main boom 204.

(34) The knuckle boom assembly comprises a main boom 204 and a jib 205. The main boom 204 comprises an inner end 204a, a central area 204b and an outer end 204c. The main boom 204 is connected at its inner end 204a pivotably to the lower portion of the crane housing 203, rotatable about a first horizontal pivot axis 214.

(35) A jib 205 is provided, comprising an inner end 205a, a central area 205b and a tip 205c opposite the inner end 205a of the jib. The inner end 205a of the jib is connected pivotably about a second pivot horizontal axis 216 to the outer end 204c of the main boom.

(36) The knuckle boom crane of this embodiment further comprises a hoist assembly 216 to hoist and lower loads. The hoist assembly comprises a hoisting cable 206, only part of which is visible in FIGS. 6a-6e. The hoisting cable 206 extends from a hoist winch 208, which is preferably positioned in or below the pedestal of the crane, via one or more sheaves, in particular a sheaves 222 at the tip 205c of the jib to a load suspension device 207.

(37) The main boom 204 and the jib 205 may be of any configuration, e.g. one of them or both may have a truss-shaped framework, but alternatively it is also conceivable that one of them or both are formed as a closed box.

(38) In order to position the jib 205 with respect to the main boom 204, according to the invention a tensioning member 211 and a curved extension guide 210 are provided. The tensioning member 211 extends between the upper portion 215 of the crane housing 203 and the curved extension guide 210. In the shown embodiment, the tensioning member 211 is connected to a central area 215b of the elongated portion 215.

(39) The curved extension guide 210 is in this embodiment approximated by a polygon, formed by the distal outer ends of spokes 210a and 210a′ which are not interconnected at their distal outer ends. Spokes 210a extend from a common hub 210b. The spokes 210a, 210a′ vary in length.

(40) According to the invention, the tensioning member extends between the crane housing and the curved extension guide. In the shown embodiment, the tensioning member 211 comprises a first portion 211a, 211a′ being guided by the curved extension guide 210 and a second portion 211b which the length may be varied by the tensioning winch 232, and as such position the jib. In the shown embodiment, the tensioning member 211 comprises multiple articulated interconnected elongated rods 211a and 211a′, being pivotably connected to the second portion 211b via pivot point 212a and being pivotably interconnected via pivot points 212b and 212c. In particular, the second portion 211b of the tensioning member comprises a cable and sheaves, wherein the length of the cable may be varied by a tensioning winch 232. The upper sheave of the second portion of the tensioning member is in the shown embodiment directly connected to the lower end of the interconnected elongated rods of the first portion of the tensioning member 211. In this embodiment, the pivot points 212a, 212b between the elongated rods 211a, 211a′, are adapted to connect to the distal ends of the ‘spokes’ 210a of the curved extension guide. Hence, as visible in FIG. 6c, the upper sheave of the shown embodiment of the tensioning member can be connected to the distal end of spoke 210a.

(41) In this embodiment, the curved extension guide 210 is mounted to the jib 205 via a connecting beam 210c, extending from spoke 210a′ and pivot axis 212c to the tip of the jib 205c. The curved extension guide 210 is pivotable together with the jib 205 about the second pivot axis 216, to which also hub 210b is mounted. Alternatively, it is also conceivable that beam 210c is part of the tensioning member, comprising consecutively first portion 211b, tow which elongated rod 211a is connected, to which rod 211a′ is connected, to which beam 210c is connected.

(42) The combination of tensioning member 211a, 211a′, 211b and a curved extension guide 210 with spokes 210a, enables an accurate control of the position of the jib 205 at a range of different positions with respect to the main boom 204: from an extended position in which the tip 205c extends mainly forward from the main boom, as visible in FIG. 6a, to a folded position in which the jib is folded back, essentially parallel along the main boom, as is visible in FIG. 6c.

(43) In order to position the main boom, a luffing cable 213 is provided, extending between the outer end 204c of the main boom 204 and the top of the crane housing 215. The luffing cable is connected to the, in particular to a sheave connected to the outer end of the main boom, or advantageously to a sheave rotatable about the second pivot axis 216 as in the shown embodiment. A luffing winch 231 is provided to allow to vary the length of the luffing cable 213 and thus to position the main boom 204.

(44) In the shown embodiment, the main boom 204 is rotatably connected to the crane housing about pivot axis 214. The luffing cable 213 is connected to the upper end of the upper portion 115, being as remote as possible from the main boom connection point. As such, a variety of positions of the main boom is possible.