WO2018166656A1

WO2018166656A1 - Lowering mechanism for pivoting davits

Info

Publication number: WO2018166656A1
Application number: PCT/EP2018/000130
Authority: WO
Inventors: Ørjan TVEIT
Original assignee: Heron Davits AS
Current assignee: Heron Davits AS
Priority date: 2017-03-31
Filing date: 2018-03-28
Publication date: 2018-09-20
Anticipated expiration: 2019-09-30
Also published as: ES2685173A1; ES2685173B1

Abstract

Drive mechanism (1) for pivoting davits (100), of the type of davits (100) comprising a frame (2) provided with at least an upper arm (8) of suspension of a boat (4) supported by the corresponding columns (10), they in turn being provided with a base (9) at a fixed part (6) of installation of the davit, the base (9) being joined to said fixed part (6) by means of an anterior horizontal articulation (5) parallel to the edge (7) of the fixed part (6) to pivot the frame (2) from a parked position to another launching position, comprising at least a linear drive (11) relating at least one of the columns (10) to the fixed part (6) to produce the pivoting of the frame (2) through the movement of the linear drive (11), said linear drive being disposed within the interior of said column (10).

Description

LOWERING MECHANISM FOR PIVOTING DAVITS

OBJECT OF THE INVENTION The present invention relates to a lowering mechanism for pivoting davits installed upon ships, oil rigs and similar launching sites, based upon a linear drive, the same being disposed within the interior of the structure of the davit, rendering it protected.

BACKGROUND OF THE INVENTION

The stowage and launching of lifeboats, auxiliary boats or fenders from ships, oil rigs and similar launching sites is realised by means of complex hoists, known as davits in the corresponding technical sector, which have evolved with the passage of time. The document US6357380 describes a rescue hoist for storing, launching and retrieving a rescue boat having an A-shaped lifting arm supporting the rescue boat in a stowed position and rotating approximately 20° about the base of the A-shaped frame to assist in hoisting and lowering the rescue boat. A sheave assembly and a hoist stop assembly are mounted upon the apex of the A-shaped frame lifting arm and accommodate a winch line at the apex of the A-shaped frame. An electrical winch raises and lowers the rescue boat, by means of a cable, and a stop ring on said cable operates in conjunction with the hoist stop fitting to cause the cable to rotate the A-shaped frame lifting arm forwards. A post assembly mounted outboard of the ship provides a support for the electrical winch and supports the A-shaped structure lifting arm. It presents the disadvantage that the rescue boat is at all times suspended outboard by virtue of the fact that the post assembly does not retract inboard with the limited movement of 20 degrees of the lifting arm around the base thereof. Nor does it present a suitable form for housing the rescue boat in an inboard position. US6626126 describes a hoisting device suspended over an associated boat comprising suspended and telescopically displaceable horizontal hoist arms to move the boat from a position of inboard stowage to a position of outboard launching, and vice versa, whilst a raising device may move the boat vertically, wherein the raising device is fixed to the hoistarms and the vertical and horizontal movements may be realised independently, in a controlled manner. It is complex by virtue of the fact that it requires suspending the hoist arms and, consequently, an upper strong structure, such as a deck or beams having large projections.

US6955519 describes a hoisting system including an elongate base having a rectilinear part and a leading part downwardly inclinable in relation to the rectilinear part. Through the interior slides a cradle transporting the boat from an interior withdrawn position to an interior position and, in order that it may be that of introduction into the water, said inclinable leading part must attain the water. It presents the disadvantage that it would not be utilisable when the height whereat the boat is stowed is very great, being the normal situation in large ships wherein the deck may be at dozens of metres above the level of the water. US2009050046 divulges an assembly of hoists for launching a boat from a ship comprising two separate hoists, each whereof includes a substantially horizontal arm, a hoisting cable extending downwards from a suspension frame upon the boom and includes at least one fixing device at the end thereof, such that the hoists move between an inward position wherein the suspension frames extend inward and an outward position, wherein the suspension frames extend outboard rotating in a horizontal plane around the (vertical) axes of each of the hoists, and wherein the suspension frames are movable along the arms such that a distance between said suspension frames remains constant during the rotation of the arms between the two positions when the boat is moved from a parked position to the launching position. It presents the disadvantage that it requires a coordination of movements between both hoists.

To solve the foregoing problems, pivoting hoists or davits are known comprising a frame provided with one or more upper arms (for suspension, raising or launching the boat) supported by the corresponding columns which, in turn, comprise a supporting base or soleplate upon a fixed part of the ship, usually the deck thereof, the base being joined to said fixed part of the ship by means of an anterior horizontal articulation substantially parallel to the side the ship such that, on the frame pivoting about said articulation between two extreme positions, the boat is parked inboard or alternatively hung outboard to then lower it by means of cables of those hanging from the upper arms. For example, the patent document US2647269 shows a possible embodiment of this variant, wherein the articulation is complex and wherein the pivoting of the hoist is realised by means of ropes or cables joined to the hoist and which are also utilised for launching the boat. It presents the disadvantage that the davit is operated by gravity and controlled by cables (the same cable for raising and lowering the boat and for moving it out to the lowering position). In this version the ropes or cables are exposed to the action of corrosion and require constant inspection and maintenance and may fail at the moment of launching.

In order to circumvent this disadvantage, nowadays the utilisation of hydraulic cylinders is selected. This is the most usual situation at the present time, there being two possible options: a first option wherein the cylinders are located within the interior of the davit upon the soleplate or base thereof, being whereat there is the necessary space, but having the disadvantage that in this position the extremities thereof cannot be applied at the most favourable points and presenting very unfavourable angles of thrust, this requiring cylinders of greater weight and cost, in addition to a larger and more powerful and expensive hydraulic unit. Furthermore, the overdimensioning of the thrust points of the davit and/or of the deck is required to support the greater stresses and determines the form of the davit, the second option being disposition of the cylinders in the most favourable position, that is to say between the deck and the columns of the frame, however this option presents the problem of the cylinders being external to the davit, leaving them exposed to corrosion and, in the case of rupture of flexible hoses or seals, involving the spillage of the hydraulic fluid to the exterior and the consequent environmental problem.

DESCRIPTION OF THE INVENTION

The lowering mechanism for pivoting davits of the invention is implemented on davits of the type comprising a pivoting frame provided with at least an upper arm of suspension of a boat (whether lifeboats or auxiliary boats) or of a fender type protection, said arms being supported by the corresponding column or columns, they in turn being provided with a supporting base or soleplate upon a fixed part of installation of the davit, the base being joined to said fixed part by means of an anterior horizontal articulation substantially parallel to the edge of said fixed part with the water (the side of the ship, for example) to pivot the frame from a parked position of the boat inboard of the edge to another launching position outboard of the edge.

Upon this basic configuration, and according to the invention, the davit furthermore comprises at least a linear drive relating at least one of the columns to the fixed part of installation of the davit to produce the pivoting of the frame through the movement of the linear drive and having the special particularity that said linear drive is disposed within the interior of said column. The fixation of the corresponding part (fixed or mobile) of the linear drive to the column may be at any point of the same, intermediate or upper or lower extremity, and the position leading to the greatest travel of the drive will preferentially be sought, signifying the necessity of lower power. Normally, said most favourable position will be in the proximity of the lower extremity of the column and/or as distant as possible from the horizontal articulation, that which transmits the force upon the most favourable point at the commencement of the pivoting. Moreover, as the movement of the linear drive is rectilinear and produces pivoting, it is necessary that at least one of the two elements (fixed or extendable) of the linear drive be joined to the column of the frame or to the fixed part of installation of the davit by means of an articulation.

In this manner the force is applied in the most appropriate point to reduce the power of the drive to the minimum, by virtue of the fact that in the parked position (inner position) practically all the force utilised to move the davit out is employed in the rotation thereof, requiring a minimum dimensioning in terms of requirements of power of the linear drive and of the strength of the points of thrust thereof, furthermore, in the normal (inner) position of storage of the boats, achieving covering the linear drives within the corresponding columns such that they are not exposed to corrosion nor to other climatological factors and, in the case of rupture of flexible hoses or seals, spillages of hydraulic fluid are retained within the interior of the columns with minimum environmental detriment and preventing personnel on deck from slipping. Moreover, having this configuration, the linear drive is practically vertical to the deck in the inner position, rendering the occupation thereby of much less space at the base of the davit. It can be provided that the linear drive comprises at least two elements. The two elements can be moveable - in particular linearly moveable - relative to each other. In a position of the frame corresponding to a parked position of the boat, the linear drive - in particular the two elements of the linear drive - can be disposed substantially completely within the interior of the column. In a position of the frame corresponding to a launching of the boat, the linear drive can be disposed at least partially within the interior of the column. In particular, in a position of the frame corresponding to a launching of the boat, at least one element of the two elements of the linear drive can be disposed at least partially within the interior of the column and at least one other element of the linear drive can be disposed at least partially on the outside the interior of the column.

Additionally, by virtue of the protected disposition of the linear drive, and application thereof upon the most propitious zones requiring least power, permits the utilisation of electric linear drives, and not exclusively hydraulic drives as at present, in this manner avoiding the disposition of the corresponding hydraulic units and the weight and environmental detriment thereof.

The following additional advantages, or those going beyond that sought, are achieved through the invention:

It greatly facilitates the work of installation of the components (e.g. motor and reducing gear), together with that of maintenance, by virtue of the fact that the components are situated in the rear part of the davit whereat the access is much better. Furthermore, a smaller number of hatches is required for installation and maintenance.

Great increase in the efficiency of the system, with greater advantage taken of the forces. - Less maintenance.

Less power required in the linear drive, it being centred within the interior of the column together with an increased distance between the point of rotation and the drive, and in the elements thereof (motors, pumps, etc), having the consequent reduction in price and weight of the assembly.

Less structural strength requirements of the frame (lesser thicknesses, less reinforcements, etc), permitting optimisation of the design thereof.

Quicker and less costly process of installation.

Reduction of the forces upon the deck, eliminating the requirement of reinforcing the deck or platform whereupon the davit will be installed.

Less space occupied within and without the davit.

Increasing the travel of the linear drive, through disposing it in the most appropriate position, permits improved control of the speed and of position. The increase in travel is very advantageous for the utilisation of electric linear drives wherein the motors thereof may work at high speed and with a lower maximum torque; the best performance may be achieved in this manner. - The force exerted by the linear drive is much more constant throughout the travel thereof (in the present systems there is a peak of consumption at the commencement of moving out the davit).

Smoother and more silent operation. Greater comfort for the persons in the boat and for the operators of the davit.

Less wear of the components by virtue of the fact that they are not subjected to peaks of stress. - Less consumption of current (it does not consume a peak of current at the commencement). This permits reducing the size of the electrical components (lower price, smaller size, smaller electrical cabinet) together with lower power supply (both in principal and in emergency use). It is also an improvement for the emergency systems by virtue of the fact that the batteries are better dimensioned if the consumption is constant.

Reduction in the peaks of force in the case of accident.

Improved internal distribution of the components.

It permits modifying the shape of the frame beneath the boat (rendering it more planar), consequently lowering the latter more in the inner position. This also permits utilising other models of boats and opens the way to changing the design of the davit. Furthermore, it opens up the possibility of reducing the total height of the davit.

It frees up space in the lower part of the davit (zone occupied by the cylinder in the present designs) to install other components, such as the oil tank.

Safety is increased (there is no element external to the davit in the inner position nor any element projecting from the structure of the davit).

Optimisation of the accumulators, which may be of the hydraulic or electric type, achieving reducing the size thereof.

It results in a more compact davit.

DESCRIPTION OF THE DRAWINGS

Figure 1 shows lateral views of the davit, each incorporating the mechanism of the invention, in the storage (inner) and launching (outer) positions of the boat, respectively.

Figure 2 shows a posterior elevation view of a version of davit having two drives, in the parked or inner position. PREFERENTIAL EMBODIMENT OF THE INVENTION

The lowering mechanism (1 ) for pivoting davits (100) of the invention is applied to davits (100) of the type comprising a frame (2) provided with at least an upper arm (8) of suspension of a boat (4), said arm or arms (8) being supported by the corresponding column (10) or columns, they in turn being provided with a supporting base or soleplate

(9) upon a fixed part (6) of installation of the davit (the deck of a ship, for example), the base (9) being joined to said fixed part (6) by means of an anterior horizontal articulation (5) substantially parallel to the edge (7) of the fixed part (6) of installation of the davit (the side of a ship, for example) to pivot the frame (2) from a parked position of the boat (4) inboard of the side (7) to another position of launching outboard of the side (7).

As a consequence of this basic configuration, and according to the invention, the mechanism (1) comprises at least a linear drive (1 1 ) relating at least one of the columns

(10) to the fixed part (6) of installation of the davit to produce the pivoting of the frame (2) through the movement of the linear drive (11 ), said linear drive (1 1 ) being disposed within the interior of said column (10). By virtue of the movement of the linear drive being rectilinear and producing a pivoting, it is necessary that at least one of the two elements (fixed or extendable) of the linear drive (11 ) comprises an articulation. Preferentially both elements of the linear drive (11 ) will be respectively articulated to the fixed part (6) of installation of the davit and to the corresponding column (10), respectively, through each having hinges (17), this permitting oscillation of the linear drive (11 ) around the same such that it adapts to the lowering movement as the linear drive operates. In order to permit said oscillation it is provided that internally the columns (10) form housings (12) broadened as necessary to permit the amplitude of said oscillation. Furthermore, it is provided that the upper hinge (17) of the linear drive (11 ) ideally be disposed upon the upper extremity of said linear drive (11 ), by virtue of the fact that in this manner said oscillations are produced in the intermediate part of the linear drive and the broadened housing may be rendered in the lower part of the column (10), lowering the centre of gravity of the frame (2) and achieving a lighter design in the upper part. Alternatively, the upper hinge (17) may be disposed in the proximity of the lower extremity of the column (10) or of the base thereof (9), this transmitting force at the most favourable point at the commencement of the pivoting. By virtue of the proposed configuration, the linear drive (1 1) may be an electric linear drive, this reducing costs and additionally facilitating the positional and speed control. However, the invention provides that the linear drive (11 ) may also be a hydraulic cylinder, having the corresponding driving unit thereof, not shown. In any of the cases the linear drive (1 1 ) is preferentially in an inverted position, that is to say having the piston or track in a lower position. This permits that the most delicate parts of the drive (vessel of the hydraulic cylinder or the actuator of the track, in the case of an electric linear drive (1 1 )) are at all times protected within the interior of the corresponding column (10). Furthermore, a possible disposition of a mechanical stop, not shown, is provided upon the linear drive (1 1 ) to prevent the disassembly thereof by virtue of excess travel.

On occasion, the mechanism for a davit (100) will comprise several linear drives (11 ) (see fig. 2) disposed upon one or several columns (10) of the frame (2), comprising at least an element of synchronisation between said linear drives (1 1 ). Said elements of synchronisation may comprise, for example, an electromechanical synchronisation, wherein by virtue of each having linear encoders, not shown, disposed upon both linear drives (11 ) the drive of the latter is synchronised such that they travel the same distance at all times. Other types of synchronisation may comprise travel sensors, shared mechanical shafts, installation of 2 motors, installation of a motor in the centre, etc.

The nature of the invention having been sufficiently described it is declared that the description of the same and the preferential manner of embodiment thereof shall be interpreted in a non-limitative manner, and that it embraces the totality of the possible variants of embodiment which may be deduced from the content of the present memorandum and of the claims.

Claims

1. Lowering mechanism (1 ) for pivoting davits (100), of the type of davits (100) comprising a frame (2) provided with at least an upper arm (8) of suspension of a boat (4) supported by the corresponding column (10) or columns, they in turn being provided with a supporting base or soleplate (9) upon a fixed part (6) of installation of the davit, the base (9) being joined to said fixed part (6) by means of an anterior horizontal articulation (5) substantially parallel to the edge (7) of the fixed part (6) of installation of the davit (100) to pivot the frame (2) from a parked position of the boat (4) inboard of the edge (7) to another launching position outboard of the edge (7), characterised in that it comprises at least a linear drive (1 1 ) relating at least one of the columns (10) to the fixed part (6) of installation of the davit to produce the pivoting of the frame (2) through the movement of the linear drive (11 ), said linear drive being disposed within the interior of said column (10).

2. Lowering mechanism (1 ) for pivoting davits (100) according to claim 1 , characterised in that the linear drive comprises at least two elements and that the two elements of the linear drive (11 ) are respectively articulated to the fixed part (6) of installation of the davit and to the corresponding column (10) by means of each having hinges (17).

3. Lowering mechanism (1 ) for pivoting davits (100) according to claim 2, characterised in that the columns (10) internally form broadened housings (12) to permit the oscillations of the linear drives (11 ).

4. Lowering mechanism (1 ) for pivoting davits (100) according to claim 2 or 3, characterised in that the upper hinge (17) is disposed upon the upper extremity of the linear drive (1 1 ).

5. Lowering mechanism (1 ) for pivoting davits (100) according to claim 2 or 3, characterised in that the upper hinge (17) is disposed in proximity to the lower extremity of the column (10) or of the base thereof (9).

6. Lowering mechanism (1 ) for pivoting davits (100) according to any of the foregoing claims, characterised in that the linear drive (1 1 ) comprises an electric linear drive.

7. Lowering mechanism (1 ) for pivoting davits (100) according to any of claims 1 to 5, characterised in that the linear drive (1 1 ) comprises a hydraulic cylinder and the corresponding actuating unit thereof.

8. Lowering mechanism (1 ) for pivoting davits (100) according to any of the foregoing claims, characterised in that the linear drive (11 ) is in an inverted position.

9. Lowering mechanism (1 ) for pivoting davits (100) according to any of the foregoing claims, characterised in that the linear drive (11 ) comprises a mechanical stop.

10. Lowering mechanism (1) for pivoting davits (100) according to any of the foregoing claims, characterised in that it comprises several linear drives (11 ) disposed upon one or several columns (10) of the frame (2), comprising at least an element of synchronisation between said linear drives (11 ).