EP2776309B1 - Towing device with a hinged fairlead - Google Patents

Description

The invention relates to a towing device for equipping the deck of a ship and for towing an object dragged behind the ship. The towing device conventionally comprises a winch, a cable and a fairlead, the cable flowing in the fairlead under the action of the winch. A known fairlead is for example described in the document US 4,455,961 . This type of device is for example implemented in the field of underwater acoustics and more particularly for towed active sonars. These sonars generally include a transmitting antenna integrated in a submersible object or "fish" and a receiving antenna consisting of a linear antenna or "flute". When using dependent towing sonar, the fish and flute are attached to the same cable to be towed by the vessel.

The cable generally comprises a core formed of electrical and / or optical conductors for transmitting energy and information between sonar equipment located on board the ship and the antennas. The core of the cable is usually covered with a strand of metal son ensuring the mechanical strength of the cable. The constitution of the cable imposes a minimum radius of curvature. Below this radius, inadmissible mechanical stress appears and causes deterioration of these elements. The winch attached to the deck of the ship has a reel on which the cable can wind when the sonar is inactive and the antennas are stored on board the ship. The diameter of the drum ensures that the coiled elements are not curved at a radius less than the minimum radius of curvature.

When the towed elements are overboard, the cable is guided by the fairlead that secures its effective radius of curvature. When towing, the vessel may change its speed and heading. Other involuntary movements of the ship can occur when the sea state is degraded, particularly in heavy weather. These movements of the ship cause a change in the direction of the cable relative to the axis of the ship. To prevent changes of direction from damaging the cable, the fairlead may be fixed relative to the ship and have a trumpet shape opening towards the rear of the ship.

In addition, underwater acoustics, the fairlead must be adapted to allow the rise of antennas on the deck of the ship. The fairlead is for example open on its upper part. The vessel can be equipped with an articulated arm allowing the fish to pass over the fairlead.

The existing devices are bulky and require an actuator for the movement of the articulated arm. In addition, when passing fish over the fairlead, it is necessary to implement anti-decapping systems to prevent the cable to which are attached the towed elements out of its housing in the fairlead.

The invention aims to overcome all or part of the problems mentioned above by providing a towing device ensuring the cable not to bend beyond a minimum radius of curvature and facilitating the passage of towed body through the fairlead. The invention also makes it possible to dispense with an articulated arm intended to grip a towed body before it reaches the fairlead during the ascent of the cable.

To this end, the subject of the invention is a towing device intended to equip the deck of a ship and comprising a winch, a cable and a fairlead, the cable circulating in the fairlead under the action of the winch, characterized in that that the fairlead comprises at least a first and a second sector, the sectors for guiding the cable in a groove formed in each of the sectors, a first joint with a degree of freedom in rotation about an axis, the joint connecting the two sectors, the axis being substantially perpendicular to a direction in which the cable extends substantially in the fairlead at the joint, means for limiting the angular movement of the joint, and in that the sectors and the limiting means are dimensioned so as to prevent the cable from exceeding a lower limit of radius of curvature.

• la figure 1 représente de façon schématique un navire tractant un sonar actif ;
• les figures 2, 3 et 4 représentent un exemple de chaumard mis en oeuvre dans un dispositif de remorquage destiné à équiper le navire pour tracter le sonar ;
• les figures 5, 6 et 7 représentent plusieurs variantes de chaumard en coupe dans un plan contenant un câble ;
• la figure 8 représente le chaumard de la figure 7 dans une autre position.

The invention will be better understood and other advantages will appear on reading the detailed description of an embodiment given by way of example, a description illustrated by the attached drawing in which:

• the figure 1 schematically represents a ship towing an active sonar;
• the Figures 2, 3 and 4 represent an example of fairlead used in a towing device intended to equip the ship to tow the sonar;
• the figures 5 , 6 and 7 represent several variants of fairlead in section in a plane containing a cable;
• the figure 8 represents the fairlead of the figure 7 in another position.

For the sake of clarity, the same elements will bear the same references in the different figures.

The invention is described in relation to the towing of a sonar by a surface vessel. It is understood that the invention can be implemented for other towed elements.

The figure 1 represents a ship 10 pulling an active sonar 11 including an acoustic emission antenna 12 often called fish and an acoustic receiving antenna 13 often called flute. The sonar 11 also comprises a cable 14 for towing the two antennas 12 and 13. The cable also provides the routing of signals and power supplies between the ship and the antennas 12 and 13 of the sonar 11.

The antennas 12 and 13 are mechanically secured and electrically and / or optically connected to the cable 14 in an appropriate manner. Conventionally, the receiving antenna 13 is formed of a tubular linear antenna identical to those found in passive sonars, hence its name flute, while the transmitting antenna 12 is integrated in a volume structure having a shape similar to that of a fish. The reception flute is generally arranged at the rear, at the end of the cable 14, the fish being positioned on the part of the cable 14 closest to the ship 10. During an underwater acoustic mission, the antenna 12 emits sound waves in the water and the receiving antenna 13 picks up possible echoes from targets on which the sound waves originating from the antenna 12 are reflected.

The receiving antenna 13 is generally permanently secured to the cable 14 while the fish 12 is, in turn, removably secured. For this purpose the cable 14 comprises a docking area 15 of the fish 12, zone in which are implanted means for fixing mechanically the fish 12 and to make its electrical and / or optical connection to the cable 14.

The launching and the exit of the water from the antennas 12 and 13 is carried out by means of a winch 16 arranged on a deck 17 of the ship 10. The winch 16 comprises a drum 18 sized to allow the winding of the cable 14 as well as the receiving antenna 13. The winding of the cable 14 makes it possible to haul the fish 12 aboard the ship 10, for example on a rear platform 19 provided for this purpose.

A fairlead 20 guides the cable 14 downstream of the drum 18. The fairlead 20 is the last guide element of the cable 14 before its descent into the water. When towing, the inclination of the cable 14 may vary with respect to the longitudinal axis of the ship 10. The variations of inclination are in particular due to the changes of heading and speed of the ship and also to the state of the sea. functions of the fairlead 20 is to ensure the cable 14 that its radius of curvature does not exceed a lower limit. The cable 14 comprises for example a core formed of electrical and / or optical conductors for transmitting energy and information between sonar equipment located on board the ship 10 and the antennas 12 and 13. The core of the cable 14 is generally covered with a strand of metal son ensuring the mechanical strength of the cable 14 including traction. Below the lower limit of curvature, there is a risk of permanent deformations or breaks in components of the cable 14.

The Figures 2, 3 and 4 represent the fairlead 20 when a fish 12, attached to the cable 14, passes through it. The figure 2 is a perspective view, the figure 3 is a view in a plane in which a curvature of the cable 14 and the figure 4 is a sectional view in a plane perpendicular to the cable 14.

According to the invention, fairlead 20 comprises at least two sectors articulated to each other. In the example shown, the fairlead 20 comprises three sectors 21, 22 and 23. A greater number of sectors is of course possible without departing from the scope of the invention.

Each of the sectors comprises a groove, 24 for the sector 21, 25 for the sector 22 and 26 for the sector 23. These grooves allowing guide the cable 14 all along the fairlead 20. They are substantially in the extension of one another. Each of the sectors 21, 22 and 23 extends substantially in the direction of the cable 14 while allowing a curvature of the cable 14. Each of the sectors 21, 22 and 23 is dimensioned so as to limit the maximum curvature of the cable 14.

In addition, the fairlead 20 comprises a hinge 27 connecting the sectors 21 and 22. The hinge 27 has only one degree of freedom in rotation about an axis 28 substantially perpendicular to a direction in which the cable 14 s' extends substantially in the fairlead at the hinge 27. The hinge having a degree of freedom in rotation is also called pivot connection.

Similarly, the fairlead 20 comprises a hinge 29 connecting the sectors 22 and 23. The hinge 29 has only one degree of freedom in rotation about an axis 30 substantially perpendicular to a direction in which the cable 14 s' extends substantially in the fairlead at the joint 29. The axes 28 and 30 of the two joints 27 and 29 remain parallel to each other during the rotation of the sectors 21, 22 and 23 relative to each other. The axes 28 and 30 are perpendicular to the plane of the figure 3 .

For each of the joints 27 and 29, the fairlead 20 comprises means for limiting their angular deflection. More specifically, the sectors 21, 22 and 23 can abut against each other in order to limit the angular displacement of each of the joints 27 and 29. This abutment of the sectors 21, 22 and 23 also limits the radius In other words, the radius of curvature of the cable 14 is limited both by the shape and the dimensions of the sectors taken separately and by the maximum amplitude of the movement of the sectors between them.

The different sectors 21, 22 and 23 allow a change of direction of the cable 14 in the plane of the figure 3 . For example, each of the sectors 21, 22 and 23 can be defined so that they allow a change of direction of the cable 14 by a maximum of 30 °. For three-way drivers, it will be possible to obtain a change of direction of up to 90 ° when the sectors 21, 22 and 23 are in abutment against each other. This change is realized in the plane of the figure 3 . The fairlead 20 limits the radius of curvature of the cable 14 during this change of direction.

It is possible to fix the sector 21 on a frame secured to the rear platform 19. In this case, the fairlead 20 will be arranged so that the joints 27 and 29 are horizontal. This arrangement makes it possible to tilt the cable 14 in a substantially horizontal direction relative to the ship 10 towards a substantially vertical direction. The horizontal direction is for example that taken by the cable 14 upstream of the fairlead 20 between the drum 18 and the fairlead 20. The vertical direction is for example that taken by the cable 14 downstream of the fairlead 20, when the cable 14 enters in water. A change of direction of 90 ° is obtained when the ship 10 is at a standstill or during the immersion of a towed body. The cable 14 thus plunges into the water vertically. The sectors 21, 22 and 23 are then all abut against each other. When the ship 10 is gaining speed, the cable 14 tilts to reduce the inclination of the change of direction. The sectors 21, 22 and 23 are no longer in abutment against each other and pivot between them around the joints 27 and 29.

This fixed provision of the sector 21 with respect to the ship 10 nevertheless has a drawback when the course of the ship is modified. In a horizontal plane, the cable 14 must then change direction with respect to the heading of the ship. This change of direction may for example be obtained by means of a trumpet shape of the last sector of the fairlead 20 which, in the example shown, is the sector 23. This trumpet shape does not allow significant changes in direction. Advantageously, the first sector 21 is hinged relative to the ship 10 to allow a greater amplitude of change of direction of the cable 14 when the ship 10 changes course. Such articulation also allows better guidance of the cable 14 over the entire length of the fairlead 20 and in particular in the last sector 23.

More specifically, the fairlead 20 comprises a frame and a hinge 40 with a degree of freedom in rotation about an axis 31, the hinge 40 connecting the sector 21 and the frame. The frame can be fixed on the ship 10, for example on the rear platform 19 or on a trancouver for the correct storage of the cable 14 on the drum 18. In the case of fixing the frame to the slicing, it is all of the fairlead 20 which translational movements parallel to the axis of the drum 18 to properly store the cable 14 on the drum 18. The axis 31 is included in a plane 32 perpendicular to the axis 28 of the hinge 27. It s' is the plan of the figure 3 which is also materialized on the figure 4 . The plane 32 can incline with respect to a vertical plane of the ship 10, especially when the ship 10 changes course. The inclination of the plane 32 is obtained when the articulation 40 pivots. When the cable 14 passes through the fairlead 20, it is always contained in the plane 32 and the forces that the cable 14 undergoes upstream and downstream of the fairlead 20 are still contained in the plane 32. The fairlead 20 pivots around the articulation 40 as a function of the direction of the forces exerted on the cable 14.

The axis 31 may be parallel to the direction that follows the cable 14 between the fairlead 20 and the winch 16. This arrangement of the joint 40 nevertheless leads to a lateral deflection of the cable 14 in the sector 21. To overcome this problem, the shaft 31 preferably intersects the groove 24 at a point 41 where the cable 14 is provided to come into contact with the groove 24 on the side of the winch 16. This orientation of the axis 31 makes it possible to significantly improve the control of the point actual entry into contact between the cable 14 and the sector 21. It is then easier to properly manage the position of the cable 14 between the fairlead 20 and the winch 16 and thus avoid the problems of bad winding of turns of the cable 14 on the drum 18. Note that when the frame is fixed relative to the ship 10, there may be a slight difference between the point 41, defined during the design of the fairlead 20, and the actual point of contact with the cable 14 on sector 21. This decal This age is for example due to the winding of several turns of cable 14 on the drum 18. This offset remains light however with regard to the possible lateral movement of the cable 14 when the axis 31 is parallel to the direction of the cable 14. when the frame is secured to a slicing the actual point of contact remains confused with the point 41.

Throughout the three sectors 21, 22 and 23, the corresponding grooves 24, 25 and 26 have substantially constant sections. On the figure 4 , we distinguish the shape of the section of one of these grooves. The groove 24 has a section having the shape of the letter C open laterally, that is to say open along an axis 33 substantially perpendicular to the plane 32. The opening 34 of the groove 24 allows possibly to insert the cable 14 in the fairlead 20. The opening 34 allows especially to pass a fixing 35 of the fish 12 along the fairlead 20. The fish 12 can thus be reassembled on board the ship 10 and be unhooked from the cable between the fairlead 20 and the winch 16. In this situation the position of the fish 12 with respect to the ship 10 can be perfectly known and mastered. The only parameter that can influence the position of the fish 12 is the control of the winch 16. It is thus possible to dispense with an articulated arm to maneuver the fish aboard the ship 10, in particular to hang and unhook the cable 14.

The figures 5 , 6 and 7 represent several variants of fairlead in section through the plane 32. These figures are shown in section in a plane passing through the axis of the cable 14, considering that the boat follows a substantially rectilinear course. In these different figures, the cable 14 is substantially horizontal upstream of the fairlead 20 between the drum 18 and the fairlead 20. Downstream of the fairlead the cable tilts 1 ° downwards. This value has been chosen so that the cable 14 is firmly supported on one of the faces of the groove of the first sector 21. It is understood that the fairleads shown in these figures can be used for other angle values.

On the figure 5 , the grooves of the different sectors 21, 22 and 23 have constant sections over most of the sector considered, with the exception of entry and exit areas of the sector in which the groove can be chamfered to avoid any risk of injuring the cable 14. In the example shown, the groove of the sector 21 has two bearing zones 36 and 37 against which the cable 14 can rest. When the cable 14 is inclined downwards, as shown in FIG. figure 5 , the cable 14 is supported on the lower zone 36 and when the cable 14 is inclined upwards, the cable is supported on the upper zone 37. The two zones 36 and 37 have a curvature centered both on a point 38 located below the fairlead 20. The radius of curvature of the zone 36 is defined by the minimum radius of curvature below which the cable 14 must not be bent. The other sectors 22 and 23 have identical zones of contact with the cable 14 and are therefore identified in the same way: 36 and 37. This variant has a utility when the inclination of the cable 14 is practically some downward downstream of the fairlead, which is most often the case during a towing operation.

On the figure 6 , for the three sectors 21, 22 and 23, we find the lower bearing areas 36 ensuring a minimum radius of curvature for the cable 14 when the latter tilts downwards. In contrast, in this variant, each sector comprises a substantially flat upper support zone 38, which makes it possible to better distribute the contact between the cable and the sectors when the cable rises downstream of the fairlead 20 until it comes into contact with each other. One or more bearing surfaces 38. There is thus less risk of wear of the areas where the cable 14 rubs in the groove.

On the figure 7 , we always found for the three sectors 21, 22 and 23, the lower bearing areas 36 ensuring a minimum radius of curvature for the cable 14 when the latter tilts down. In this variant, each sector comprises an upper bearing zone 39 whose curvature is inverted relative to that of the lower zone 36 to allow the cable 14 to rise upstream downstream of the fairlead during repeated use. It is useful in this variant to provide a possible abutment of the three sectors between them to prevent the cable exceeds a limit curvature upwards.

The figure 8 represents the fairlead of the figure 7 in a position where the cable 14 has an inclination of 31 ° downwardly downstream of the fairlead 20. In this figure, the cable 14 is wound on the drum 18 by successive layers and in one of the last layers, the inclination the cable between the drum 18 and the fairlead 20 increases relative to the first layer. The sector 21 is sized to allow the entry of the cable 14 whatever the layer on the drum 18.

Claims (8)

1. A towing device intended to equip the deck of a vessel (10) and comprising a winch (16), a cable (14) and a fairlead (20), said cable (14) passing through said fairlead (20) under the action of said winch (16), characterised in that said fairlead (20) comprises at least one first and one second sector (21, 22), said sectors allowing said cable (14) to be guided in a groove (24, 25) made in each sector (21, 22), a first hinge (27) with a rotational degree of freedom about an axis (28), said hinge (27) connecting said two sectors (21, 22), with said axis (28) being substantially perpendicular to a direction along which said cable (14) substantially extends in said fairlead (20) at said hinge (27), means for restricting the angular displacement of said hinge (27), and in that said sectors (21, 22) and said restriction means are designed so as to prevent said cable (14) from exceeding a lower radius of curvature limit.
2. The device according to claim 1, characterised in that it comprises a third sector (23) and a second hinge (29) with a rotational degree of freedom about an axis (30), said second hinge (29) connecting said second sector to said third sector, said axis (30) of said second hinge being parallel to said axis (28) of said first hinge (27).
3. The device according to any one of the preceding claims, characterised in that said fairlead (20) comprises a frame and a third hinge (40) with a rotational degree of freedom about an axis (31), said third hinge (40) connecting said first sector (21) and said frame, said axis (31) of said third hinge (40) being within a plane (32) that is perpendicular to said axis (28) of said first hinge (27).
4. The device according to claim 3, characterised in that said axis (31) of said third hinge (40) intersects the groove (24) of said first sector (21) at a point where said cable (14) is designed to make contact with said groove (24) of said first sector (21) on the side of said winch (16).
5. The device according to any one of the preceding claims, characterised in that the grooves (24, 25, 26) of the various sectors (21, 22, 23) have substantially constant, laterally open C-shaped sections.
6. The device according to any one of the preceding claims, characterised in that each of said grooves (24, 25, 26) has a lower abutment zone (36) and an upper abutment zone (37, 38, 39), against which said cable (14) can come into abutment, and in that said lower abutment zone (36) has a curvature that is centred on a point (38) that is located underneath said fairlead (20).
7. The device according to claim 6, characterised in that said upper abutment zone (38) is substantially flat.
8. The device according to claim 6, characterised in that said upper abutment zone (39) has a curvature that is reversed relative to that of said lower abutment zone (36).

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