System and apparatus for motion compensation and anti-pendulation

Abstract

A system and assembly for providing anti-sway and motion compensation while handling ISO containers in high sea states up to and above sea state four between a lighter or other floating body and a crane ship. The contemplated invention enables the transfer of cargo containers between a container ship and a lighter or other floating body at sea in sea states up to and higher than sea state four by synchronizing the motion of the container and the lighter or floating body.

Claims

1. A system for motion compensation and anti-pendulation comprising: a crane having an electric cable signal cable reel; a rope rigging system, comprising of rigging wire or rope connected to the crane at a lift point; a spreader assembly, connected to the crane via the rope rigging system and used to connect with a container wherein the spreader assembly comprises of: at least one anti-sway winch having anti-sway lines, a hydraulic power unit, at least one variable pressure accumulator connected to the hydraulic power unit and at least one ram tensioner and a hydraulic piping system connecting the at least one variable pressure accumulator, at least one ram tensioner and the hydraulic power unit.

2. The system of claim 1 wherein the spreader assembly further comprises of rope chocks for guiding the anti-sway rope to deck fittings of a lighter or floating body container landing spot.

3. The system of claim 1 wherein each at least one ram tensioner comprises of three ram tensioner sheaves for each at least one ram tensioner and two fair lead sheaves for each at least one ram tensioner.

4. The system of claim 1 wherein an end point of the rope rigging system may be anchored to a base of the at least one ram tensioner.

5. The system of claim 4 wherein there are two ram tensioner sheaves at the top of the at least one ram tensioner and one turnaround ram tensioner sheave at the bottom of the at least one ram tensioner.

6. The system of claim 4 wherein the rigging wire or rope passes over at least one ram tensioner sheave to a turnaround sheave at the bottom of the at least one ram tensioner.

7. The system of claim 4 wherein the rigging wire or rope passes over two fair lead sheaves and on to the lift point.

8. The system of claim 1 wherein the at least one variable pressure accumulator is configured to change pressure in the at least one ram tensioner in order to accommodate different containers with different weights and to facilitate motion compensation when the container is landing on a lighter deck or other floating body.

9. The system of claim 8 wherein the hydraulic power unit comprises of a variable displacement pump configured to change volume of hydraulic oil within the at least one variable pressure accumulator in order to: enable accommodation of different containers with different weights and to provide tension within the anti-sway lines, by way of the anti-sway winches, to prevent payload pendulation while being handled by the shipboard crane between the ship and lighter or other floating body.

10. The system of claim 9 wherein a first variable pressure accumulator of the at least one variable pressure accumulator serves the at least one ram tensioner while a second variable pressure accumulator of the at least one variable pressure accumulator serves the anti-sway winches.

11. The system of claim 1 wherein the spreader assembly further comprises of lock/unlock device(s) and flipper guide(s) for securing the spreader assembly to the container.

12. A spreader assembly for motion compensation and anti-pendulation comprising: at least one anti-sway winch mounted thereon wherein the at least one anti-sway winch comprises of anti-sway lines or rope; a hydraulic power unit, positioned and mounted on the spreader assembly; at least one ram tensioner connected to the hydraulic power unit and also mounted on the spreader assembly; at least one variable pressure accumulator, wherein the at least one variable pressure accumulator is connected to the at least one ram tensioner and the hydraulic power unit and wherein the at least one variable pressure accumulator is mounted on the spreader assembly; and a hydraulic piping system connecting the at least one variable pressure accumulator, the at least one ram tensioner and the hydraulic power unit.

13. The spreader assembly of claim 12 wherein the spreader assembly further comprises of rope chocks for guiding the anti-sway rope to deck fittings of a lighter or floating body container landing spot.

14. The spreader assembly of claim 12 wherein each of said at least one ram tensioner comprises of three ram tensioner sheaves for each said at least one ram tensioner and two fair lead sheaves for each said at least one ram tensioner.

15. The spreader assembly of claim 14 wherein there are two ram tensioner sheaves at a top of the at least one ram tensioner and one turnaround ram tensioner sheave at a bottom of the at least one ram tensioner.

16. The spreader assembly of claim 12, wherein the spreader assembly is operationally connected to a crane via a rope rigging system having rigging wire or rope and wherein the spreader assembly and the crane are both used to lower or lift a container.

17. The spreader assembly of claim 16 wherein the spreader assembly is structurally configured to enable an end point of the rigging wire or rope to be anchored to a base of the at least one ram tensioner.

18. The spreader assembly of claim 16 wherein the spreader assembly is structurally configured to enable the rigging wire rope to pass over at least one ram tensioner sheave to a turnaround sheave at a bottom of the at least one ram tensioner.

19. The spreader assembly of claim 16 wherein the spreader assembly is structurally configured to enable the rigging wire rope to pass over two fair lead sheaves and on to a lift point.

20. The spreader assembly of claim 16 wherein the at least one variable pressure accumulator is configured to change pressure in the at least one ram tensioner in order to accommodate different containers with different weights and to facilitate motion compensation when the container is landing on a lighter deck or other floating body.

21. The spreader assembly of claim 20 wherein the hydraulic power unit comprises of a variable displacement pump configured to change volume of hydraulic oil within the at least one variable pressure accumulator in order to: enable accommodation of different containers with different weights and to provide tension within the anti-sway lines, by way of the at least one anti-sway winch, to prevent payload pendulation while being handled by a shipboard crane between a ship and a lighter or other floating body.

22. The spreader assembly of claim 12 wherein a first variable pressure accumulator of the at least one variable pressure accumulator serves the at least one ram tensioner while a second variable pressure accumulator of the at least one variable pressure accumulator serves the anti-sway winches.

23. The spreader assembly of claim 16 wherein the spreader assembly further comprises of lock/unlock device(s) and flipper guide(s) for securing the spreader assembly to the container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a crane handling a spreader assembly and container landing on a deck of a lighter or other floating body according to an aspect of an embodiment of the present invention.

(2) FIG. 2 illustrates a plan view of a spreader assembly and motion compensation components mounted on the spreader assembly according to an aspect of an embodiment of the present invention.

(3) FIG. 3 illustrates an elevation view of a spreader assembly to indicate the relative location of the components on the spreader assembly according to an aspect of an embodiment of the present invention.

(4) FIG. 4 illustrates a container landing spot on the lighter or other floating body.

DETAILED DESCRIPTION OF THE INVENTION

(5) Referring now to FIGS. 1 through 4, aspects of embodiments of a motion compensation anti-pendulation system are shown. The motion compensation anti-pendulation system may include a shipboard crane 1 having an electric and cable reel 2 which may be connected to a control cable 3 that is further attached to hydraulic power unit 12 mounted on an ISO cargo container spreader assembly 4. Crane 1 may be used to transfer container 10 from the crane ship to a container landing zone 22 of a lighter or other floating body in high sea states up to and including 4 or higher. Anti-sway winches 5 and wire rope chocks 6 may also be provided on spreader assembly 4 to guide the anti-sway wire rope 7 to the deck securing fitting fittings 18-21which are on the landing deck 23 or container landing zones 22 of the lighter or other floating body. The above fittings together with motion compensation components mounted on the spreader assembly 4 are provided to facilitate a soft landing of container 10 onto the deck of the lighter or other floating body or container landing zone.

(6) After the deck crew on the crane ship passes the anti-sway control lines 7 to the deck crew on the lighter or other floating body for securing to the deck securing fittings 18-21, the transfer operation continues (FIG. 1). During the lowering operation, back tension is applied to lift point 17 so that the anti-sway control lines 7 will develop enough tension to control anti-pendulation during the lowering operation. Tension is realized by controlling the lowering speed of crane 1 and also controlling the speed of anti-sway winches 5 so that winches 5 are pulling container 10 down to lighter deck 23. As the pay load or container 10 approaches landing spot 22 of the lighter or other floating body, tension is increased until motion compensation is initiated in the ram tensioners 9. This is due to the wave motion on the lighter or other floating body which will cause the motions of the pay load and lighter or other flotation body to synchronize with each other to assure a soft landing of the pay load 10 on landing spot 22 of landing deck of lighter 23.

(7) Referring specifically now to FIGS. 2 through 4 a plan view of spreader assembly 4, an elevation view of spreader assembly 4 indicating the relative location of the different components on the spreader assembly 4, and a plan view showing landing spot 22 of lighter deck or floating body 23 are all illustrated according to aspects of embodiments of the present invention. Spreader assembly 4 is shown having wire rope rigging 8 arrangement of four ram tensioners 9 with three ram tensioner sheaves 16 and two fair lead sheaves 11 leading to the crane lift point 17. The end point of wire rope rigging element 8, in one aspect of an embodiment of the present invention, may start at or be anchored to the base of ram tensioner 9 and pass over the top of ram tensioner sheave 16 and leading on to turnaround sheave 16 at the bottom of ram tensioner 9. Wire rope rigging element 8 may, in an aspect of an embodiment of the present invention, further extend on to two fair head sheaves 11 and on to crane lift point 17. The hydraulic components mounted on the spreader assembly 4 may include a hydraulic power unit 12 which receives electric power and control signals from the power and control cable 3 on the crane boom 1. The hydraulic components mounted on the assembly 4 may include a hydraulic power unit 12 and two variable pressure accumulators 13 and 14. In an aspect of an embodiment of the present invention, variable pressure accumulators 13 and 14 operate by first hydraulic oil contained within them using nitrogen gas bottles in a fixed volume. Next, hydraulic power unit 12, which has a variable displacement pump, is utilized to change the volume of the oil which in turn changes the pressure in variable pressure accumulators 13 and 14. This will also change the pressure in the variable pressure accumulators to suit the change in weight of various containers. Further, this allows for the increase in the tension of the anti-sway control lines or ropes 7 to facilitate motion compensation from wave action on the lighter and cause the motion of container 10 and the lighter to synchronize. Variable pressure accumulators 13 and 14 are connected to ram tensioners 9 and anti-sway winches 5 by a hydraulic piping system (not shown).

(8) In an aspect of an embodiment of the present invention, one variable pressure accumulator may serve the ram tensioners 9 while another variable pressure accumulator may serve the anti-pendulation winches 5. Spreader assembly 4 may also be fitted with hydraulic controlled bayonet cone container lock/unlock devices 15 and flipper guides 24 which all may be used to secure spreader assembly 4 to container 10. As discussed above, variable pressure accumulators 13 and 14 are provided, in an aspect of an embodiment of the present invention, to change the pressure in the ram tensioners 9 to accommodate containers with different weights and to facilitate motion compensation when container 10 is landing on the lighter's deck or other floating body container's landing spot 22.

(9) In an aspect of an embodiment of the present invention, operation of system may begin with an operator using shipboard crane 1 pickup spreader assembly 4 from its stowage position. Crane 1 with spreader assembly 4 attached, will then be used to pick up container 10 by aligning, engaging and locking devices. Crane 1 will then position container 10 over the lighter at the side of the ship and the ship deck crew will pass anti-sway lines or ropes 7 to the lighter's deck crew for connecting to securing fittings 18-21 on the lighter.

(10) In an aspect of an embodiment of the present invention, the lowering operation may be initiated with crane 1 lowering spreader assembly 4 which is engaged with container 10 and anti-sway winch(es) 5 pulling container 10 down to the lighter. This assures anti-pendulation and the increase in tension will cause the motion of container 10 and the lighter to synchronize for a soft landing of container 10 onto landing deck 23 of the lighter within the desired landing spot 22. After container 10 has been secured within landing spot 22, anti-sway lines or ropes 7 are then disconnected and retracted and the operation can be repeated for additional loads or containers.

(11) The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.