In lifting operations under water, there are used, besides the common connecting links such as shackles and drop-out hook couplings, also couplings of the"collar lock"type. Both the collar lock and the drop-out hook coupling are quick release coupling types, which can be locked or released through simple operations.

A collar lock is formed to grip around a cylindrical portion in which there is arranged a collar at the free end portion thereof. The collar lock is provided with a bore of a diameter adapted to the diameter of the collar, so that it can be slipped over the collar. At a suitable distance from the end

portion of the collar lock, there are arranged in the bore two cylindrical countersunk hollows formed as steps of different depths. The shallower countersunk hollow nearer to the end portion of the collar lock forms the locking hollow. A sleeve, whose locking end portion has a cylinder-shaped bead, is posi- tioned in the bore. The locking end of the sleeve is split axially into many segments, so that the locking end of the sleeve consists of many"fingers", each of them with part of the cylindrical bead placed at its free end portion. The ge- ometry of the bead at the inner surface of the sleeve comple- mentarily matches the collar, whereas its geometry at the ex- ternal surface of the sleeve complementarily matches the coun- tersunk hollow nearer to the end portion of the bore.

Prior to connection, the sleeve is carried to a position, so that the beads of the sleeve have an axial position in the bore, which coincides with the deeper countersunk hollow posi- tioned within the countersunk hollow which the beads lock into. Because this countersunk hollow is deeper, the fingers can pivot into it when they are slipped over the collar. By the spring force of the fingers the beads at the inner portion of the sleeve (and fingers) will be positioned behind the col- lar. The collar coupling housing is then carried axially rela- tive to the sleeve, so that the beads at the outer portion of the sleeve are positioned in the countersunk hollow, in which the beads are locked and thereby prevented from moving out of the collar. As the coupling is released, load is removed therefrom, and the collar coupling housing is carried axially relative to the sleeve into a position, in which the beads of the outer portion of the sleeve are positioned over the deeper countersunk hollow, so that they can pivot into it when the sleeve is pulled out over the collar.

In a drop-out hook coupling a load-carrying hook is connected at one end to a housing by means of a hinge. In a bore in the housing is positioned a locking spindle. The housing is pro- vided with an internal threaded portion for attachment to the lifting equipment. The locking spindle, which can be displaced axially in the bore of the housing, is arranged to be placed, in its locked position, in a locking hole in the hook. The drop-out hook coupling is opened in that the locking spindle is displaced out of the hole of the hook, after which the hook may pivot about the hinge and release the load hanging on the hook.

Both types of quick release couplings can be manoeuvred me- chanically, hydraulically or pneumatically.

In work under water the connection links must be operated by a diver or a ROV (Remote-Operated Vehicle). Alternatively the types of quick release couplings can be operated from the sea surface, by for example a hydraulic connection from an aggre- gate on a ship to an actuator in the coupling.

The use of divers or ROVs is very expensive and complicating in offshore operations. The same applies to the use of long control lines from the surface to great sea depths, which can also result in an unreliable function.

The object of the invention is to remedy the negative aspects of existing equipment, the new technique making use of a novel coupling of the multi-dog type and power elements, in which a phase change in a memory metal is used indirectly to operate a locking element of the coupling, which enables the use of a simple and functionally reliable remote control equipment.

A coupling of the multi-dog type according to the invention, has, for example, an outer part (the female part) with a bore, in the cylindrical surface of which there is arranged one or more annular countersunk hollows. The coupling parts are also provided with a securing device for connection to a load or a piece of lifting equipment. The inner part (male part) of the coupling is formed so, that a cylindrical part of it can be inserted into the bore of the outer part. In this cylindrical part are arranged two or more axial slots, with a locking dog being suspended resiliently on a hinge shaft in each slot, so that within a limited sector it may pivot in and out from/towards the centre line of the coupling. In a loaded state the locking dogs will rest on the bottom of the axial slot, whereas in the unloaded state they will spring back and have a clearance to the bottom of the axial slot. The clear- ance can be adjusted through, e. g., an adjustment screw lo- cated in the locking dog and tightening against the hinge shaft. A locking body may be inserted into a bore, in between the locking dogs when they are in a locked position pivoted outwards.

When the two main parts of the coupling are being brought to- gether, the locking body is positioned outside the sector, within which the locking dogs may pivot, so that the locking dogs can adopt a position pivoted inwards. The inner part of the coupling may thereby be inserted into the outer part of the coupling. When the coupling parts are in correct relative positions, the locking dogs pivot outwards and engage the countersunk hollows of the outer part. The locking body is then inserted between the locking dogs and prevents them from pivoting back in towards the centre of the coupling when the coupling is loaded. Thereby the coupling forms a fixed me- chanical connection.

Releasing of the coupling can take place when it is unloaded, in that the locking body is carried out of the area of the pivoting sector of the locking dogs. The locking dogs may then be pivoted inwards, out of the countersunk hollows of the outer coupling, and the inner part of the coupling may be pulled out of the outer part.

When using a multi-dog coupling, collar lock and also other types of couplings, it is necessary to move one or more lock- ing elements to control the locking function of the coupling.

According to the invention the locking element is suspended between two types of springs, which pull or push the locking element in opposite directions. In this connection a spring may consist of several springs or spring systems. In a pre- ferred embodiment the force of a conventional spring will in- fluence the locking element in a direction towards the locked position, whereas the force of a memory metal spring will work in the opposite direction.

The memory effect of the memory metal may be explained as the material appearing in two different structural phases. In its cold state the material has an easily mouldable martensite structure, with a yield strength of e. g. about 70 MPa, and above the transformation limit an austenite structure with a yield strength of e. g. about 210 MPa. By a change in the pro- portion of mixture of e. g. nickel and titanium in the memory metal alloy, the temperature of transformation between the martensite and austenite structures may be kept in the range from-100 °C to +100 °C. Memory metals are also known, which may have two positions, depending on the temperature, without mechanical influence, i. e. the metal adopts one geometry under the influence of heat and another geometry when the metal is

cooled. Memory metals are well known in themselves and are commonly available, and therefore are not an object of this patent application.

When the main parts and locking dogs of the multi-dog coupling are in the locking position, the ordinary spring, which af- fects the locking body and has a greater tension than that of the memory metal springs in their cold state, will overcome the force of the memory metal springs and push the locking body into the locked position. When the coupling is to be re- leased in the unloaded state, the memory metal is heated. The structure is then changed to the mechanically strong austenite state. The increased force of the memory metal springs is suf- ficient to overcome the force of the ordinary spring. Thereby the locking body is carried away from the locking position, so that the dogs can pivot in towards the centre of the coupling in order, thereby, to release the mechanical connection be- tween the coupling parts.

A further development of the invention consists in the ar- rangement, at the coupling, of a manoeuvring/battery pack which is connected to the memory metal springs. This unit can be controlled from the sea surface by the use of known ra- dio/sonar technique. Warm liquid and/or chemical energy in the form of reaction heat from two or more materials can also be used as a heat source.

In the following there will be described several non-limiting examples of preferred embodiments, which are visualized in the accompanying drawings, in which:

Fig. 1 is a principle drawing showing the main components in- cluded in a releasable lifting arrangement according to the invention, wherein the main parts such as load, couplings, lifting equipment and manoeuvring/battery pack are shown; Figs. 2a and 2b show, in sections, an embodiment of the inven- tion as a multi-dog coupling, part"a"showing the coupling in a connected, locked position, part"b"showing it in the par- tially joined, unlocked position; Figs. 3a and 3b show, in sections, the details of the locking body of Fig. 2 on a larger scale, there being shown in part "a"the same position as that in Fig. 2a, whereas part"b"is showing the same position as that in Fig. 2b; Figs. 4a and 4b show in sections a multi-dog coupling, in principle similar to that of Figs. 2a and 2b, but with a sim- plified locking mechanism in an embodiment with a push-out bolt; Fig. 5a-5d show, in sections, an embodiment of a collar lock with lock manoeuvring according to the invention, part"a" showing it in its closed position; part"b"showing it in an intermediate position, whereas part"c"is showing the lock in an open position, part"d"showing a section Va-Va of Fig.

5a; Figs. 6a and 6b show, partly in sections, a device according to the invention used in a drop-out hook coupling, part"a" showing the coupling in a closed position, part"b"showing the coupling in an open position;

Figs. 7a and 7b show, partly in sections, details of the sus- pension of the locking dog (see Fig. 2), Fig. 7 showing it from the front, Fig. 7b showing it in a side section.

In Fig. 1 the reference numeral 1 identifies a load which is to be positioned and then disconnected from a piece of lifting equipment 4. A spring-operated multi-dog coupling in the form of an outer part 2 and an inner part 3 is connected through a wire 6 to a manoeuvring/battery pack 5 controlled by a trans- mitter not shown. The coupling parts 2 and 3 are shown here in a disconnected state. Respective bores 26 and 27, Fig. 2a, are arranged to connect the coupling parts 2 and 3, respectively, to the lifting equipment. A locking body 13 is arranged to lock one or more locking dogs 8 in the locked position. During insertion of the inner part 3 of the coupling into the outer part 2, the locking body 13 is positioned in a retracted posi- tion, and the locking dogs 8 are pivoted about a hinge shaft 11 in towards the centre of the coupling. See Fig. 2b. A con- ventional compression spring 14 is tightened and forces the locking body towards the locking dogs 8. Just before the inner part 3 of the lock has been carried into its locking position in the outer part 2 of the lock, a stop 10 on the locking dog 8 is arranged so that it abuts a shoulder 12 in the outer part 2 of the coupling. On further insertion, the locking dogs 8 are brought to pivot outwards about the hinge shaft 11, so that the teeth 9 of the locking dogs 8 engage the countersunk hollows 7 of the outer part 2. The spring 14 may now displace the locking body 13 into a locked position behind/between the locking dogs 8, see Fig. 2a.

Memory metal springs 15, see Fig. 3a, are arranged in a corre- sponding number of pipes 16 with a bottom/spring support 17,

to which one end portion of the memory metal spring 15 is con- nected. The opposite end portion of the memory metal spring 15 is connected by means of a tension spring dog 18''to a ten- sion rod 18 connected to the locking body 13 through a screw 18'and an insulating securing element 19. At its opposite end portion relative to the bottom/spring support 17, the pipe 16 is connected to a surrounding conventional spring 20. The op- posite end portion of the spring 20 is connected to an insu- lating nut 21, which is threaded on to a screw 22. The head 22'of the screw 22 tightens against an electrically conduc- tive plate 23, fixedly located in an insulating support 24. A guide sleeve 25 for the spring 14 is positioned in the support 24 by means of a screw connection 25'. A cover 24'is secured to the coupling part 3 by bolts 24''and washers 24'''.

Through adjustment of the preload, the memory metal springs 15 may be calibrated to provide identical force.

The hinge shaft 11, see Figs. 7a and 7b, is arranged to spring downwards when the locking dogs 8 are loaded, so that the locking dog 8 may bear on the bearing surface 3""of the inner part 3. When the locking dogs 8 are unloaded, they will be lifted from the bearing surface 3""and thereby have the nec- essary clearance to easily pivot about the hinge shaft 11. At its top the locking dog 8 is provided with an adjustment screw 52, which is arranged to adjust the distance between the bear- ing surface 3""and the locking dog 8 when the locking dog 8 is in an unloaded state. The distance between the bearing sur- face 3""and the locking dog 8 is increased by screwing the adjustment screw 52 in towards the hinge shaft 11.

When, by unloaded coupling, the locking body 13 is to be car- ried out of its locking position, a voltage is applied to the

memory metal spring 15 through the plate 23, the screw 22 bearing against the bottom/spring support 17 and the tension rod 18 which are earthed. The heat which then develops through the ohmic resistance of the memory metal spring 15, brings it into the strong austenitic phase, whereby it contracts by three times the force it had in its cold state. Together the memory metal springs 15 overcome the force of the conventional spring 14 and carry the locking body 13 out of its locking po- sition. The lock arms 8 can now pivot inwards towards the cen- tre of the coupling, and the inner part 3 can be carried out of the outer part 2.

If, during the heating and contracting, one of the memory metal springs 15 is not able to move the mount 19, it will ex- tend the conventional spring 20, whereby the bottom/spring support 17 is pulled out from the screw 22, so that the elec- trical contact is broken. Se detail IIIa in Fig. 3a. This ar- rangement prevents the memory metal spring from becoming over- heated, with the risk that it may lose its predetermined ge- ometry.

A multi-dog coupling 2,3 in Fig. 4 has a simplified embodi- ment for the change of position of the locking body 13. The internal coupling part 3 is provided with an internal threaded portion 3''for attachment to the lifting equipment 4. The configuration of the locking dogs 8 is as described above. A conventional compression spring 14 is suspended between a sleeve 3'connected to the internal coupling part 3 and the locking body 13. It pushes the locking body 13 in the direc- tion towards locked position, whereas a memory metal spring 38, suspended between the internal coupling part 3 and a flange 13'on the locking body 13, pushes the locking body 13

in the direction of its unlocked position. The locking body 13 is provided with a fixedly connected spindle 13''.

When the unloaded coupling is being released, see Fig. 4a, the memory metal spring 38 is heated, for example electrically through wires not shown, so that it adopts the relatively strong austenite structure. The memory metal spring 38 then overcomes the force of the spring 14 and displaces the locking body 13 out of the pivoting segment of the locking dogs 8, whereby they may pivot about the shaft 11 out of the counter- sunk hollows 7. On further displacement of the locking body 13, the spindle 13''abuts a bottom 2'in the outer locking part 2 and presses against this. The inner part 3 of the lock is thereby carried out of its locked position.

A collar lock housing 28, see Fig. 5a, is provided with a bore 29 adapted to the diameter of a collar 30, so that the bore 29 can be slipped over the collar 30. Two cylindrical countersunk hollows 31,32 are formed as steps of different depths. The shallower countersunk hollow 31, nearer to the end portion 33 of the collar lock, is the locking hollow. A sleeve 34, of which an active end portion has a cylinder-shaped bead 35, is positioned in the bore 29. The locking end of the sleeve 34 is split axially into many segments, so that the locking end of the sleeve consists of many"fingers"36, each of them having a portion of the cylindrical bead 35 forming the free end por- tion. The geometry of the bead 35 at the internal surface of the sleeve fits complementarily into an annular groove 30'be- low the collar 30, whereas the geometry of the bead 35 at the external surface of the sleeve 34 fits complementarily against the countersunk 31 the most adjacent to the end portion 33 of the bore. The fingers 36 act as blade springs, and allow the

beads 35 of the end portions of the fingers 36 to be moved resiliently radially outwards, but will themselves seek back to their initial shape when unloaded. A spindle 39'is fixedly connected at its upper end portion to the collar lock housing 28.

Prior to connection, the sleeve 34 is brought into a position, in which its beads 35 have an axial position in the bore 29 coinciding with the deeper countersunk hollow 32, Fig 5c. Be- cause this countersunk hollow 32 is deeper than the counter- sunk hollow 31, the beads 35 of the fingers 36 can pivot into the countersunk hollow 32 when they are passed over the collar 30. By the spring force of the fingers 36, the beads 35 at the inner portion of the sleeve 34 (and fingers 36) will be posi- tioned behind the collar 30, Fig. 5b. The collar coupling housing 28 is then displaced axially relative to the sleeve 34, so that the beads 35 at the outer portion of the sleeve 34 are positioned in the countersunk hollow 31, in which the beads 35 are locked and thereby prevented from moving out from the collar 30. As the unloaded coupling is being released, a memory metal spring 38 is heated, for example through electri- cal energy through wires, not shown, whereby the metal struc- ture is transformed to the mechanically relatively strong aus- tenite structure. The force of the memory metal spring 38 thereby overcomes the force of a conventional spring 37 and first pushes, through the flange 39'', a spindle 39 down to- wards the collar 30, whereby it also displaces the collar cou- pling housing 28 axially relative to the sleeve 34, into a po- sition in which the beads 35 are positioned over the deeper countersunk hollow 32, so that they can pivot into it when the sleeve 34 is pulled out over the collar 30. See Fig. 5b. Then the memory metal spring 38 forces the spindle 39 towards the collar 30, while pressing at the same time against the sleeve

34. The beads 35, now being free to move into the countersunk hollow 32, out of a position in the hollow 30', are pushed over the collar 30 into a free position. See Fig. 5a. The con- struction of the coupling allows the passing of a guide line (not shown) through the bore 39'of the spindle 39.

The coupling may be provided with a position lock 49, whose object is to ensure further that the coupling is not inadver- tently brought out of the predetermined position. The position lock 49 locks the sleeve 34 in an upper or lower position by engaging one of the two grooves 50 arranged in the sleeve 34.

The movement of the position lock 49 is achieved by using the same mechanism as that described above to cause the movement of the sleeve 34, namely a conventional compression spring 49' and a memory metal spring 49''. Energy is supplied to the mem- ory metal spring 49''through not shown electrical wires.

In a drop-out hook coupling 40, Fig. 6a, a drop-out hook 41 suspended from a housing 42 by means of a hinge (48), is locked by a locking spindle 43. The housing 42 is provided with an internal threaded portion 42'for attachment to the lifting equipment 4.

The locking spindle 43, which may be displaced axially in a bore 45 of the housing 42, is arranged to be placed, in its locked position, in a locking hole 44 of the drop-out hook 41.

The locking spindle 43 is retained in its locked position by a conventional compression spring 46, spanning between a gable 51 of the housing 42 and the spindle 43. A memory metal spring 47 is used, which is extended relative to its programmed ge- ometry.

When being heated, the memory metal spring 47, which is insu- latingly suspended between the gable 51 of the housing 42 and the spindle 43, will overcome the force of the compression spring 46 and thereby pull the locking spindle 43 out of the locking hole 44 of the drop-out hook 41, Fig. 6b. The drop-out hook 41 will then pivot about the hinge pin 48 and thereby open the drop-out hook coupling 40.

The invention allows lifting and positioning work in connec- tion with, for example, underwater work to be simplified, be- cause the release couplings may be remote-controlled from the sea surface.