Drive system for a spud carrier

Abstract

A spud system for a dredging vessel with a longitudinal direction includes a spud carrier for mounting a spud therein in a vertical stance and which spud carrier is moveable with respect to the dredging vessel in a longitudinal direction for advancing the dredging vessel, a spud carrier drive system coupled with the dredging vessel and the spud carrier for driving the spud carrier with respect to the dredging vessel. The spud carrier drive system includes a hydraulic drive cylinder for controlling the position of the spud carrier. The spud system further comprises a hydraulic system comprising a parallel hydraulic cylinder in fluid parallel connection with the hydraulic drive cylinder and presstressing means coupled with a rod of the parallel hydraulic cylinder such that said rod is forced towards a central position.

Claims

1. A spud system for a dredging vessel with a longitudinal direction, which spud system comprises; a spud carrier for mounting a spud therein in a vertical stance and which spud carrier is moveable with respect to the dredging vessel in a longitudinal direction for advancing the dredging vessel, a spud carrier drive system coupled with the dredging vessel and the spud carrier for driving the spud carrier with respect to the dredging vessel, wherein the spud carrier drive system comprises a hydraulic drive cylinder for controlling the position of the spud carrier, and a hydraulic system comprising a parallel hydraulic cylinder in fluid parallel connection with the hydraulic drive cylinder and presstressing means coupled with a rod of the parallel hydraulic cylinder such that said rod is forced towards a central position.

2. The spud system according to claim 1, wherein the presstressing means comprise a self centring cylinder.

3. The spud system according to claim 1, wherein the rod of the hydraulic parallel cylinder is coupled with a rod of the self centring cylinder.

4. The spud system according to claim 1, wherein the rod of the hydraulic parallel cylinder and the rod of the self centring cylinder are of one-piece and form a common rod of the hydraulic parallel cylinder and the self centring cylinder.

5. The spud system according to claim 4, comprising a control cylinder wherein a rod of the control cylinder is coupled with the common rod for providing auxiliary control of the centring force.

6. The spud system according to claim 1, wherein the hydraulic drive cylinder and parallel hydraulic cylinder have a similar configuration with respect to bore and rod diameter for facilitating position control of the spud carrier.

7. The spud system according to claim 2, comprising an accumulator system coupled with the self centring cylinder for providing a desired centring force and a desired spring action for the rod of the self centring cylinder.

8. The spud system according to claim 1, wherein the self centring cylinder comprises a pair of opposite pressurized fluid chambers the rod of the self centring cylinder is provided with a central flange or piston arranged such that the opposite pressurized fluid chambers exert the centring force on the rod of the self centring cylinder.

9. The spud system according to claim 8, wherein the pair of opposite pressurized fluid chambers are in fluid connection with the accumulator system.

10. The spud system according to claim 8, wherein the accumulator system comprises a common source of pressure and the pair of opposite pressurized fluid chambers are in fluid connection with the common source of pressure.

11. The spud system according to claim 7, wherein the accumulator system comprises a number of respective sources of pressure and pressurized fluid chambers are each in fluid connection with a respective source of pressure.

12. The spud system according to claim 7, wherein the accumulator system comprises an accumulator with an adjustable gas pressure in order to be able to adjust the centring force.

13. The spud system according to claim 2, wherein the rod of the self centring cylinder is provided with a free piston and the centring force is exerted through said free piston.

14. The spud system according to claim 2, wherein the rod of the self centring cylinder is provided with a pair of opposite free pistons arranged at opposite sides of the central flange and the centring force is exerted through said pair of opposite free pistons.

15. The spud system according to claim 4, wherein a self centring cylinder housing is provided with a stop for defining the central position of the common rod.

16. A dredger comprising the spud system of claim 1.

Description

DESCRIPTION OF THE DRAWINGS

(1) The invention will be further elucidated referring to the following schematic drawings wherein shown in:

(2) FIG. 1 is a side view of a spud system for a dredging vessel;

(3) FIG. 2a is a hydraulic scheme for operating the drive cylinder of a spud system according to the invention;

(4) FIG. 2b, is a detail of the hydraulic scheme of FIG. 2a, wherein an alternative prestressing means is shown;

(5) FIG. 2c is a detail of an alternative of the hydraulic scheme of FIG. 2b;

(6) FIG. 2d shows a detail of an alternative of the hydraulic scheme of FIG. 2c; and

(7) FIGS. 3a-3c show different characteristics of the spud force versus the spud position obtainable with the spud system according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(8) FIG. 1 shows in side view a spud system 1 for a dredging vessel (not shown). Such a spud system engages the bottom 6 of a body of water 5, like a river. The spud system 1 engages the bottom through a number of spuds 4. In general one of these spuds 4 is driveable and in FIG. 1 only the drivable spud 4 is shown. The driveable spud 4 is mounted in a spud carrier 3 also referred to with spud carriage. The spud 4 is mounted with the spud carrier 3 in a vertical stance. A spud carrier drive system, in the form of a hydraulic drive cylinder 2, for controlling the position of the spud carrier 3 is coupled with the dredging vessel and the spud carrier 3 for driving the spud carrier with respect to the dredging vessel. The assembly of the spud carrier 3 and spud 4 is coupled with the hydraulic drive cylinder 2 spud carrier cylinder 2 for driving the spud 4 with respect to the vessel. The hydraulic drive cylinder 2 is also referred to with spud carrier cylinder 2. The spud 4 is driven by the spud carrier cylinder 2 and is moveable in a longitudinal direction of the vessel for stepwise advancing the vessel.

(9) FIG. 2a shows an hydraulic scheme of a hydraulic system for operating the drive cylinder, that is the spud carrier cylinder 2, of a spud system 1. The hydraulic drive cylinder 2 has a piston 21 and fluid chambers 20, 22 on both sides of the piston 21, and a piston rod 23 firmly coupled with the piston 21.

(10) The spud system comprises a hydraulic system comprising a parallel hydraulic cylinder 7 in fluid parallel connection with the hydraulic drive cylinder 2. The parallel hydraulic cylinder 7 has a piston 16 and fluid chambers 15, 17 on both sides of the piston 16 and a piston rod 11 firmly coupled with the piston 16. The fluid parallel connection means that fluid lines 18, 19 are in fluid connection with corresponding fluid chambers 20, 22, 15, 17 of the spud carrier cylinder 2 and the parallel hydraulic cylinder 7 such that a parallel circuit is formed. The fluid lines 18, 19 are in fluid connection with a source of pressurized fluid known per se, which source is suitable to drive the spud carrier cylinder 2.

(11) The hydraulic system of the spud system 1 comprises presstressing means referred to with 8. The prestressing means 8 is coupled with the rod 11 of the parallel hydraulic cylinder 7 such that said rod 11 is forced towards a central position as shown in FIGS. 2a-2d. In this case, the presstressing means comprise a self centering cylinder 8, which is known per se. The self centering cylinder 8 has a flange 25 and fluid chambers 24, 26 on both sides of the flange 25 and a piston rod.

(12) The rod 11 of the hydraulic parallel cylinder 7 is firmly coupled with the rod of the self centering cylinder 8. In this case, the rod 11 of the hydraulic parallel cylinder 7 and the rod of the self centering cylinder 8 are of one-piece and form a common rod of the hydraulic parallel cylinder and the self centering cylinder.

(13) The hydraulic drive cylinder 2 and parallel hydraulic cylinder 7 have a similar configuration with respect to bore and rod diameter for facilitating position control of the spud carrier 3.

(14) As described, the self centering cylinder 8 comprises a pair of opposite pressurized fluid chambers 24, 26. Here, the rod of the self centering cylinder 8 is provided with a central flange 25 arranged such that the opposite, pressurized, fluid chambers exert the centering force on the rod of the self centering cylinder through the central flange.

(15) The rod of the self centering cylinder 8 is provided with a free piston 12, 13 and the centering force is exerted through said free piston 12, 13. Such a free piston 12, 13 abuts the central flange 25. In this case, the rod of the self centering cylinder 8 is provided with a pair of opposite free pistons 12, 13 arranged at opposite sides of the central flange 25 and the centering force is exerted through said pair of pistons. The self centering cylinder housing 35 is provided with a stop 14 for defining the central position of the common rod 11.

(16) The hydraulic system of the spud system 1 comprises an accumulator system (not shown) which is known per se. The accumulator system is coupled with the self centering cylinder 8 for providing a desired centering force and a desired spring action for the rod of the self centering cylinder. As an example, such a known accumulator system may comprise an accumulator with an adjustable gas pressure in order to be able to adjust the centering force. The pair of opposite pressurized fluid chambers 24, 26 of the centering cylinder 8 are in fluid connection with the accumulator system. Preferably, a desired centering force and a desired spring action can be set individually for each of the pressurized fluid chambers 24, 26. Therefore, the accumulator system comprises a number of respective sources of pressure and the pressurized fluid chambers 24, 26 are each in fluid connection with a respective source of pressure.

(17) The hydraulic system of FIG. 2a will result in characteristics designated 9a showing the spud force versus the spud position in FIG. 3a. In this figure the spud force is represented by the y-axis and the allowed deviation of the spud out of the neutral position is represented by the x-axis.

(18) FIG. 2b shows a detail of the hydraulic scheme of FIG. 2a, wherein an alternative prestressing means 8 is used. In general only differences are described. Compared with the prestressing means in FIG. 2a, the free pistons 12, 13 are omitted, as well as the stop 14 of the self centering cylinder housing 35. Therefore, the centering force is exerted through the piston 27. The fluid chambers 24, 26 on both sides of the piston 27 act directly on the piston 27. This will result in characteristics designated 9b of the spud force versus the spud position graph shown in FIG. 3b. This characteristic 9b is also referred to as spring mode. The characteristics shown can vary depending on the accumulator system and its related settings.

(19) FIG. 2c shows a detail of an alternative of the hydraulic scheme of FIG. 2b. In general only differences are described. There is provided a control cylinder 10. The rod 29 of the control cylinder 10 is coupled with the common rod 11 for providing auxiliary control of the position of the centralising force. This provides even better adjustment of the centering force. The control cylinder 10 has a piston 31 and fluid chambers 30, 32 on both sides of the piston 31. The rod 29 is coupled with the common rod 11 through piston 27 of the prestressing means 8. Fluid lines 33, 34 are in fluid connection with corresponding fluid chambers 30, 32 of the control cylinder 10. The fluid lines 33, 34 are in fluid connection with a source of pressurized fluid known per se, which source is suitable to drive the control cylinder 10.

(20) FIG. 2d shows a detail of an alternative of the hydraulic scheme of FIG. 2c in that the control cylinder 10 is integrated in the common rod 11. The alternative will not be described in detail. Corresponding parts have been numbered accordingly. The alternatives of FIGS. 2c and 2d will result in characteristics designated 9c of the spud force versus the spud position graph shown in FIG. 3c.

(21) It will also be obvious after the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. Starting from this disclosure, many more embodiments will be evident to a skilled person which are within the scope of protection and the essence of this invention and which are obvious combinations of prior art techniques and the disclosure of this patent.