The present invention relates to an arrangement and to a method for installing a propulsion unit.
The propulsion unit that is used in an azimuthal propulsion system is connected to the hull of the ship via steering gear. When the propulsion unit is turned around its vertical axis and the direction of the propiulsion force will be deviated from the longitudinal axis of the ship and the propulsion unit steers the ship.
The azimuthal propulsion unit may be mechanical or electrical. If the azimuthal propulsion unit is mechanical, the driving unit normally locates inside the hull of the ship. The driving unit may be an electric motor or a combustion motor like diesel. The propulsion force is transmitted via mechanical gears and shafts to the propeller. If the azimuthal propulsion unit is electrical, the propulsion power is lead to the propulsion unit via electric cables or via bus bars to the electric motor that locates the propulsion unit.
The azimuthal propulsion unit is attached to the hull of the ship under the water-line of the ship. The upper part of the propulsion unit is attached to the hull watertight so that the connection allows the turning of the propulsion unit around vertical axis.
Both the mechanical and the electrical propulsion unit consists of many components that require maintenance and service actions. Some of the actions even necessitates either docking or remove of the propulsion unit in order to perform the needed operations.
The docking of the whole ship is time consuming and expensive operation and there are quite a few docks available. In case of semisubmersible rig type drilling platform docking is practically impossible. Therefore the removal and the installing of the propulsion unit under water has been a useful course of action. There are several solutions to perform the underwater installations of the propulsion unit.
Patent document U.S. Pat. No. 4,035,136 A discloses an apparatus for mounting and dismounting a submerged propeller unit to and from the hull of a ship from the outside thereof. The removable, watertight housing of the propulsion is secured over the flanged opening in the hull, whereby the propeller unit is to be received to the opening. The propeller unit is positioned in the water outside the body and raised to bring a flange thereon in registry with the flange around the opening in the hull, and the two flanges are secured together in watertight relation by fastenings put in place by tools located within the watertight housing that are operable from a location outside the housing. The propeller unit is adapted to be raised into position by cables detachably secured thereto which extend through watertight passages formed in the hull. This apparatus requires a large dome to be stored inside the hull of the ship and even in the neighbourhood of the propulsion unit. Further special equipment is needed for tightening the bolts and pressurizing the dome as well as for transferring or lifting the dome. The space inside the hull is limited and valuable.
An object of the present invention is to provide an arrangement and a method so as to alleviate the above disadvantages. The object of the invention is achieved with an arrangement and a method, which are defined in the independent claims. Some embodiments are disclosed in the dependent claims.
An arrangement for installing a propulsion unit to a hull of a ship, wherein the propulsion unit comprises an upper part of the propulsion unit attachable to the hull of the ship and a lower part of the propulsion unit where to a propeller shaft is rotatably supported, and the upper part of the propulsion unit having flanges to attach the flanges tightly to the hull, and wherein there is an aperture in the bottom of the hull where to the propulsion unit is to be installed. The arrangement comprises a frame plate with openings attached to the hull to cover the aperture, a plurality of watertight covers covering openings in the frame plate and plurality of watertight covers attachable to the top of the upper part of the propulsion unit to cover an opening on the top of the upper part of the propulsion unit, wherein the arrangement comprises a removable hull-side cover covering at least one opening in the frame plate under it, and at least one removable cover attachable to the propulsion unit covering one opening under it and facing the opening in the frame, and wherein the removable covers are bolted from the hull-side.
An arrangement for installing a propulsion unit to a hull of a ship, wherein the propulsion unit comprises an upper part of the propulsion unit attachable to the hull of the ship and a lower part of the propulsion unit where to a propeller shaft is rotatably supported, and the upper part of the propulsion unit having flanges to attach the flanges tightly to the hull, and wherein there is an aperature in the bottom of the hull where to the propulsion unit is to be installed. The arrangement comprises a plurality of watertight covers covering openings in the bottom of the hull and a plurality of watertight covers covering the top of the upper part of the propulsion unit, wherein the arrangement comprises a hull-side cover covering at least one first opening under it, and at least one removable propulsion unit side cover covering a second opening under it and facing the first opening, and wherein the removable cover are bolted from the hull-side.
A method for installing a propulsion nit to a hull of a ship, wherein the propulsion unit comprises an upper part of the propulsion unit attachable to the hull of the ship and a lower part of the propulsion unit where to a propeller shaft is rotatably supported, and the upper part of the propulsion unit having flanges to attach the flanges tightly to the hull, and wherein there is an aperture in the bottom of the hull where to the propulsion unit is to be installed. The method comprises a step of attaching a frame plate with openings to the hull to cover the aperture, steps of a plurality of water-tight covers covering openings in the frame plate and of installing a plurality of watertight covers covering an opening on the top of the upper part of the propulsion unit, wherein at least one removable hull-side cover covering at least one opening in the frame is faced to at least one removable propulsion unit side cover covering the opening under it, and wherein the removable covers are bolted from the hull-side.
Big domes and lifting heavy parts inside thruster room are not needed at all in invented solution. Water tight small double flanges are used to prevent sea water ingress. In addition, steering gear frame structure is used as a watertight element in propulsion unit side. Watertight blanking flange is used as a basement of the slip ring unit. Removal of slip ring unit is not needed during propulsion unit replacement procedure installation and storage don't require any extra space in thruster room, normal maintenance space is sufficient for storage of relatively small watertight double flanges. Installation time is reduced significantly.
In addition initial cost is reduced due to smaller amount of material. Installation time and material cost is reduced.
Minimal space is needed in thruster room. No lifting of heavy components is needed leading to improved work safety.
In the following, the invention will be described in greater detail by means of some embodiments with reference to the accompanying drawings, in which
The embodiments relate to some exemplary implementations of the invention. The presentation shows the installation of the propulsion unit phase by phase and only shows the required parts in each phase. Each part is identified with the same reference number in each Figure.
In the
The first opening 24 is covered by a first watertight cover 32, which is from the inside of the hull fixed with bolts to the frame plate 18. The second openings 28 are covered by second watertight covers 34, which are from the inside of the hull fixed with bolts to the frame plate 18. From the seaside of the hull 2 there are three openings visible, the first opening 24 blanked with the first watertight cover 32 and two second openings 28 blanked with two pieces of the second watertight covers 34. Further, the underside of frame plate and holes 21 of the bolts 19 are covered with blanking ring or blanking plate (not shown) to prevent marine fouling before propulsion unit installation. Blanking plate or blanking ring is removed just prior to propulsion unit installation. The covers 32 and 34 are installed to hull-side in order to make openings water tight and are attached to the hull 6 via frame plate 18.
The
The third opening 46 is covered by a third watertight cover 50, which is bolted water tightly to the flange plate 40. The fourth openings 48 are covered by a fourth watertight covers 52, which are bolted water tightly to the flange plate 40.
The third opening 46 has the same horizontal location as the first opening 24, when the propulsion unit 2 has been installed to the hull 6. In other words if the third and first openings have round periphery, their midpoints coincide. Similarly the fourth openings 48 has the same horizontal location as the second openings 28, when the propulsion unit 2 has been installed to the hull 6. In other words as the fourth and second openings have round periphery, their midpoints coincide.
The third opening for electric cables, pipes and cooling air channels and the fourth openings for steering motor assemblies 30 are blanked water tightly by blanking flanges, i.e. by the third and the fourth watertight covers. Dummy pinion 39 with one teeth is integrated to one blanking plate of steering motor assemblies 30 flange in order to lock the gear ring. The grease channels (not shown) of the slewing bearing are plugged with watertight plugs.
The diameter of the first opening 24 is slightly larger than the diameter of the third cover 50. Likewise the diameter of the second openings 28 are slightly larger than the diameter of the fourth covers 52. The clearance range between the opening and the cover introduced to the opening is quite small as the guiding is controlled by the lifting and guiding elements. When the propulsion unit 2 has been located and lifted (
The
The third and fourth watertight covers are propulsion unit-side watertight covers. The watertight plugs in the holes 21 and holes 42 are replaced with connection bolts 54, which will fix the propulsion unit 2 to the hull 6. Accordingly, watertight plugs or short connection bolts of upper part of steering module are replaced with connection bolts 54. As long as the propulsion unit 2 has been installed and fixed to the hull 6, the first and second watertight covers bolted to the frame plate as well as the third and the fourth watertight covers bolted to the flange plate 40 are still in place shown in
The next phase of installing the propulsion unit to the hull of the ship is to dismount the watertight covers covering all the openings. First the blanking plates are removed from the upper part of the steering module. After this one of the fourth covers is removed thus revealing the gearing in the upper part of the propulsion unit. The first steering motor and planet wheel is mounted to the upper part of the propulsion unit whereas the other of the fourth covers having dummy pinion 39 is still in bolted to the upper part of the propulsion unit to prevent rotation of propulsion unit 2 (
After the first steering motor has been installed the last cover, i.e. the other fourth cover is detached and removed, and the second steering motor will be installed. If there are more than two steering motors with gear, the latest steering motor to be installed is the one with dummy pinion 39 and its blank plate will removed after the other steering motors have been installed.
When the second cover covering the midpoint of the propulsion unit has been removed the slip ring unit is coupled to the propulsion unit electric cables. In addition pipe connections are made between upper and lower parts. Further the torque tube 56 is installed and fixed between the slip ring unit and the lower part, i.e. propulsion unit 2 in order to fix the slip ring unit to rotate with the propulsion unit.
The
The
The first to fourth watertight covers, which are named as blanking plates, are made of steel or other strong and resistant material having basically the characteristics as material used in the hull of the ship. The thickness of the covers are rated for the circumstances prevailing under the sea level in the depth of the bottom of the hull. The thickness of the covers also is dimensioned so that the covers located one upon the other during installation have sufficient space. Thus the thickness of the removable third cover is smaller than the thickness of the frame plate as the third cover is introduced into the opening in the frame plate 18.
The watertight covers need riot be totally even through their total cross section have to fulfil the rated requirements described in the paragraph above. Thus the covers may have strengthening projections or even slight curvature. Preferably, the side of the cover facing to the seawater is even. The circumferences of the covers have a plurality of holes for the fixing bolts.
The propulsion unit 2 shown in
In a so-called L-drive the propulsion unit comprises a vertical shaft rotated by motor above it and a first bevel gear and horizontal shaft locating in the lower part of the propulsion unit. The motor may locate in the upper part of the propulsion unit or above the propulsion unit inside the hull of the ship.
In a so-called Z-drive the propulsion unit comprises a vertical shaft rotated by a second bevel gear above it and a first bevel gear and horizontal shaft locating in the lower part of the propulsion unit. The second bevel gear is connected to the shaft of a motor locating inside the hull of the ship.
When installing the propulsion unit with mechanical thruster the arrangement comprises an equipment to connect the transmission element to attach a vertical shaft of the propulsion unit to a vertical shaft above the propulsion unit.
It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.
Number | Date | Country | Kind |
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15160813 | Mar 2015 | EP | regional |
Number | Name | Date | Kind |
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4036163 | Pehrsson | Jul 1977 | A |
8926382 | Van Der Kam | Jan 2015 | B2 |
9708032 | Ruostemaa | Jul 2017 | B2 |
20120058694 | Krautkramer | Mar 2012 | A1 |
Number | Date | Country |
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0167503 | Jan 1986 | EP |
S599220487 | Dec 1984 | JP |
8403478 | Sep 1984 | WO |
Entry |
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European Search Report, EP15160813, ABB Technology AG, dated Jan. 6, 2017, 4 pages. |
International Search Report and Written Opinion, PCT/EP2016/056401, ABB Technology AG, 9 pages, dated Mar. 23, 2016. |
Number | Date | Country | |
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20180009519 A1 | Jan 2018 | US |
Number | Date | Country | |
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Parent | PCT/EP2016/056401 | Mar 2016 | US |
Child | 15714793 | US |