Abstract:
A submersible vehicle launch and recovery system comprises a grab comprising at least two arms capable of moving relative to each other, the arms being rotatable between an open position and a closed position, in which closed position the jaws of the arms are able to grip a handling feature on a submersible vehicle. The arms comprise attachment means so arranged that the arms tend to close when the system is suspended by the said attachment means, at least one arm comprising buoyancy means so distributed as to tend to open the said arm when the system is submerged.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to the handling of underwater machines, and in particular to a submersible vehicle launch and recovery system.  
         [0003]     2. Description of the Relevant Art  
         [0004]     Systems for launching and recovering submersible vehicles come in the form of a cage that can be open or closed to release or recover the submersible vehicle. Document FR 2 823 485 discloses a system having an upper frame and lower frame forming a cage, the frames being moveable vertically relative to each other to either secure the submersible vehicle or release it.  
         [0005]     However, such launch and recovery systems are unsuitable for some types of submersible vehicle, particularly submersible vehicles with fragile external equipment on an outer surface of the vehicle, such as propulsion units or measuring instruments. In this case there is a risk of damage to this equipment.  
       SUMMARY OF THE INVENTION  
       [0006]     It is desirable to provide a submersible vehicle launch and recovery system suitable for handling submersible vehicles that have fragile external equipment, and that is simple to use.  
         [0007]     A submersible vehicle launch and recovery system in one embodiment, includes a grab including at least two arms capable of moving relative to each other, the arms being rotatable between an open position and a closed position, in which closed position the jaws of the arms are able to grip a handling element on a submersible vehicle, the arms including attachment means so arranged that the arms tend to close when the system is suspended by the attachment means, at least one arm including buoyancy means so configured as to tend to open the arm when the system is submerged.  
         [0008]     The system in the form of a grab may be used to easily pick up a handling feature projecting from a submersible vehicle without the risk of bumping into equipment on the outside of the vehicle. Once the submersible vehicle-handling element is correctly positioned relative to the jaws, the simple act of raising the arms will cause the said jaws to close on the handling feature, so that the submersible vehicle may easily be gripped by the launch and recovery system. Moreover, provided the buoyancy means are appropriately distributed, the jaws of the arms will open spontaneously during submersible vehicle launch when the vehicle is lowered into the water, at the point when the buoyancy means are partly or completely submerged.  
         [0009]     In one embodiment the arms are arranged in a cross and connected rotatably about a hinge pin at the intersection of the arms. Each arm may include, at a first end situated on one side of the hinge pin, a jaw and a buoyancy means, and, at a second end situated on the other side, arm attachment means.  
         [0010]     In one embodiment a buoyancy means is provided in the form of a hollow float equipped with fluid filling and evacuation means, the fluid being air and/or water in particular. This makes it easy to control the buoyancy of the buoyancy means in order to open the arms of the launch and recovery system at the desired depth.  
         [0011]     In one embodiment the arms are provided with guide means for acting on a handling feature provided on a submersible vehicle. The guide means are designed to guide the movements of the submersible vehicle in order to position the handling feature between the jaws of the movable arms in order to get the submersible vehicle in position for recovery.  
         [0012]     In one embodiment the guide means include a V guide converging on a space situated between the jaws of the arms. In this way the submersible vehicle may be advanced between the jaws, guided by the V guide.  
         [0013]     In one embodiment the guide means include at least one end stop located on an arm and designed to horizontally arrest a handling feature situated on a submersible vehicle. The submersible vehicle can thus be advanced in such a way as to position the handling feature between the jaws. The end stops will define the longitudinal position of the handling feature between the jaws before the arms can be closed and the submersible vehicle recovered.  
         [0014]     In one embodiment the end stops are provided with protuberances arranged so as to prevent a reverse movement of a handling element once the latter is engaged against the end stops.  
         [0015]     In one embodiment the system includes means for limiting the opening of the grab formed by the arms. Such means may be provided in the form of a flexible or rigid element attached at one end to one arm and at the other end to the other arm to prevent the separation between the arms increasing beyond a predetermined limit.  
         [0016]     Also described herein is an assembly including a launch and recovery system and a handling feature designed to be attached to a submersible vehicle and configured so as to engage with the jaws of the launch and recovery system.  
         [0017]     In one implementation, a handling feature includes a T-shaped profile having a web designed to be gripped by the jaws and a transverse bar for vertical support. Other forms are possible.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The present invention and its advantages will be understood more clearly on examining the detailed description of an embodiment taken as an example, without in any way implying any limitation, and illustrated in the appended drawings, in which:  
         [0019]      FIG. 1  is a perspective view of a submersible vehicle launch and recovery system;  
         [0020]      FIG. 2  is a side view of the system shown in  FIG. 1 ; and  
         [0021]      FIG. 3  is a perspective view of the launch and recovery system shown in  FIG. 1  and of a submersible vehicle positioned where it can be recovered by the system. 
     
    
       [0022]     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawing and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     In  FIG. 1  the launch and recovery system  1  includes a grab  2  formed by two arms  3 ,  4  arranged in a cross and coupled together by a hinge pin  5  at the intersection between the arms  3 ,  4 . Top ends of the arms  3 ,  4  have means of attachment, here in the form of rings passed through holes in the ends of the arms  3 ,  4 . A lifting sling  6  comprises a main ring  7  and two lines  8 , each line being coupled at one end to the main ring  7  and at the other to the arm  3 ,  4  attachment means.  
         [0024]     The system  1  includes an opening limiter that takes the form of a link  9  whose ends are attached to the top ends of the arms  3 ,  4  in such a way that the link  9  inhibits separation of the top ends of the arms  3 ,  4  and thus limits the opening of the arms  3 ,  4 . The link  9  may for example be a metal rod, a sling, a chain or a cord.  
         [0025]     The lower ends of the arms  3 ,  4  have a C-shaped profile so that each bends towards the other arm at the bottom. Frames  10 ,  11  are attached to the lower ends of the arms  3 ,  4 , respectively. Each frame  10 ,  11  has a generally flat tubular perimeter  12  and reinforcing tubes  13  extend between the perimeter  12  and an intermediate portion of the arms  3 ,  4 . On the mutually facing sides of the perimeters  12  are jaws  14 ,  15  designed to come together when the arms  3 ,  4  are closed. The perimeters  12  include oblique tube portions  16 ,  17  opposite each other, and these continue on from the jaws  14 ,  15  towards the rear. The tube portions  16 ,  17  form a V guide that converges on the space lying between the jaws  14 ,  15 .  
         [0026]     The frames  10 ,  11  have end stops  18 ,  19  mounted on the frames  10 ,  11  above the jaws  14 ,  15 . The end stops  18 ,  19  have upper surfaces  20 ,  21 .  
         [0027]     As can be seen more clearly in  FIG. 2 , an end stop  19  has a first surface  21  that terminates at the forward end, away from the V guide, in an approximately vertical abutment surface  22 . At the other end, towards the V guide, the end stop  19  includes a non-return protuberance  23  presenting towards the abutment surface  22  a low abutment wall  24  that is not as high as the abutment surface  22 , and presenting in the other direction an inclined surface  25 .  
         [0028]     Returning to  FIG. 1 , on the outwards side of the frames  10 ,  11  away from the jaws  14 ,  15 , are cylindrical floats  26 ,  27  at a lateral distance from the hinge pin  5  of the arms  3 ,  4 .  
         [0029]     In  FIG. 3 , a submersible vehicle  30  includes a main body that includes two superposed and parallel tubular parts  31 ,  32 , and propulsion means in the form of propulsion units  33 , of which there are four in the present case, arranged on either side of each of the tubular parts.  
         [0030]     The submersible vehicle  30  is equipped with a handling feature  34  attached to the top of the vehicle. The handling feature  34  forms a T in profile and comprises a flat longitudinal web  35  extending upwards from the vehicle surface and supporting at its upper end a transverse bar  36  perpendicular to the web  35 . The web  35  has an enlarged base  37  with means for attaching it to the shell of the submersible vehicle  30 , such as drillings for bolts.  
         [0031]     In the form shown in  FIG. 3 , the submersible vehicle  30  positions itself beneath the grab  2  in such a way that the handling feature  34  is positioned between the jaws  14 ,  15  ( FIG. 2 ) of the grab  2 . The transverse bar  36  positions itself above the jaws  14 ,  15 , more precisely above the surfaces  20 ,  21 , ( FIG. 2 ) of the end stops  18 ,  19  ( FIG. 2 ).  
         [0032]     The operation of the submersible vehicle launch and recovery system is described below.  
         [0033]     During recovery, the submersible vehicle  30  is initially positioned in the water. The system  1  is placed in the water a matter of some meters away from the submersible vehicle. The floats  26 ,  27 , being held up by their buoyancy, cause the jaws  14 ,  15  to open spontaneously as far as the limiter  9  will allow. The vehicle  30  is then remotely driven by an operator at low speed until the handling feature  34  is between the jaws  14 ,  15  of the system  1 . The limiter  9  is adjusted so that the maximum separation between the jaws  14 ,  15  is less than the length of the transverse bar  36  of the handling feature  34 . The handling feature  34  cannot be moved vertically between the open jaws  14 ,  15  without the transverse bar  36  being stopped by the jaws  14 ,  15 .  
         [0034]     The submersible vehicle  30  is manoeuvred to insert the handling feature  34  horizontally between the jaws  14 ,  15  from the rear, that is from the V guide side, and in such a way that the shell of the vehicle  30  passes underneath the frames  10 ,  11  while the transverse bar  36  of the handling feature  34  passes above them. Vertical propulsion units on the vehicle may be used for this purpose to present the handling feature  34  at the correct height.  
         [0035]     There is a sufficient gap between the transverse bar  36  of the handling feature  34  and the shell of the submersible vehicle  30  to allow the transverse bar  36  to pass over the protuberances  23  under these circumstances. By contrast, the abutment surfaces  22  of the end stops  18 ,  19  are tall enough to prevent the transverse bar  36  passing over them.  
         [0036]     In the event of poor lateral alignment, the handling feature  34  comes into contact with the edges of the V guide, thus realigning the handling feature  34 .  
         [0037]     When the handling feature  34  is between the jaws  14 ,  15 , vertical propulsion units on the vehicle can be used to lower the vehicle and hence lower the transverse bar  36  onto the end stops  18 ,  19 . In all cases the sling  6  is then tensioned by applying an upward vertical force on the main ring  7 , helping to press the transverse bar  36  firmly onto the tops of the end stops  18 ,  19 . The two lines  8  of the sling  6  also exert an upward force on the top ends of the arms  3 ,  4  as illustrated by the arrows F 1  which tends to pivot the arms  3 ,  4  relative to each other about the pin  5  in such a way that jaws  14 ,  15  move towards each other as shown by the arrows F 2 . When the sling  6  is sufficiently taut, the jaws  14 ,  15  close and grip the web  35 , ensuring that the submersible vehicle  30  is held firmly.  
         [0038]     A forward movement of the vehicle relative to the grab is inhibited by the abutment surfaces of the end stops  18 ,  19 . Also, because the transverse bar  36  of the handling feature  34  is resting vertically on the top surfaces of the end stops  18 ,  19 , the abutting walls  24  of the protuberances  23  now inhibit any rearward movement of the handling feature  34  and therefore of the submersible vehicle  30 . The vehicle  30  is held in place longitudinally between the jaws  14 ,  15 .  
         [0039]     To facilitate closure of the grab  2 , the floats can be weighted to reduce their buoyancy and so reduce jaw-opening forces. For this purpose, arrangements may be made to fill the floats  26 ,  27 , for example with water, when the handling feature  34  is between the jaws  14 ,  15 , while the latter are still open or once they are closed.  
         [0040]     Once the system is out of the water, the weight of the floats  26 ,  27  exerts a downward load on the ends of the arms  3 ,  4 , helping to close the grab  2 , and consequently helping to hold the vehicle  30  firmly between the jaws  14 ,  15 .  
         [0041]     In a variant, automatic guidance of the submersible vehicle  30  may be provided. For this purpose the system may be equipped with transmitting or receiving beacons which cooperate with corresponding beacons on the submersible vehicle to give the submersible vehicle  30  indications as to the relative positions of the system  1  and the submersible vehicle  30 . This information can be used by means of automatic control of the vehicle  30 .  
         [0042]     If the vehicle is being positioned by remote control by an operator, a video camera may be installed on the system  1 , for example on the hinge pin  5  of the arms  3 ,  4  to observe the approach of the submersible vehicle  30 .  
         [0043]     For recovery operations, the system, installed on a ship, can be launched when the ship is either stationary or moving. In this case, recovery can be performed with the ship moving, the device being towed behind the ship or alongside.  
         [0044]     For launching the submersible vehicle  30 , the vehicle is picked up from a storage platform by the launch and recovery system  1 . The tension of the sling  6  and the weight of the floats  26 ,  27  help to keep the grab  2  closed. The system is lowered into the water. When the floats  26 ,  27  of the system  1  are in the water they experience an upward floating force, causing the arms  3 ,  4  to open. As long as the closing force applied by the sling  6  is greater than the opening force applied by the floats  26 ,  27 , the grab  2  remains closed.  
         [0045]     To release the vehicle, the system  1  can be lowered to a depth at which the opening force exerted by the floats  26 ,  27  is sufficient to open the grab  2  spontaneously.  
         [0046]     It is also possible to use vertical motors on the vehicle  30  to move it upwards and relieve the grab  2  of the weight of the vehicle  30 . This will reduce the force acting on the sling  6  and the grab  2  can then be opened by the action of the floats  26 ,  27 .  
         [0047]     Vertical and horizontal motors on the submersible vehicle  30  can then be used to release the handling feature  34  by raising and reversing the vehicle  30  rearwards to get it over the protuberances  23 . Once the submersible vehicle  30  is free, it can be moved about freely. During the mission of the vehicle  30 , the system  1  can be left in the water or hoisted back onto the platform if necessary.  
         [0048]     To adjust the depth at which the grab will open, for example if it is wished to release the vehicle at a certain depth of water, the buoyancy of the floats can be varied, for example by ballasting the floats, notably by filling them with sea water.  
         [0049]     The invention provides an underwater vehicle launch and recovery system capable of gripping an underwater vehicle without damaging it because the grab is capable of gripping the underwater vehicle through a dedicated handling feature present on the vehicle, preferably on the top of the underwater vehicle. The risk of collision between the system and the external equipment of the submersible vehicle is lessened.  
         [0050]     The launch and recovery system can be employed with ease because the grab of the launch and recovery system is closed simply by suspending the launch and recovery system, and opened simply by lowering the launch and recovery system into the water.  
         [0051]     Further modifications and alternative embodiments of various aspects of the invention may be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description to the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims. In addition, it is to be understood that features described herein independently may, in certain embodiments, be combined.