Abstract:
A subsea connector comprises a female element ( 1 ) defining a parallel bore ( 2 ) adapted to receive a male element ( 3 ). First releasable locking means are disposed between elements ( 2 ) and ( 3 ) and comprise a sprung cage ( 6 ) in which balls ( 5 ) are retained for movement in tapered grooves circumferentially spaced around element ( 3 ). As the cage moves relative to element ( 3 ) balls ( 5 ) protrude from the cage to a greater or lesser extent to lock the elements together. Second locking means prevent relative movement between elements ( 1 ) and ( 3 ) in a locking release direction of the first releasable locking means. These second locking means comprise lock balls retained in an apertured body disposed between elements ( 1 ) and ( 2 ).

Description:
TECHNICAL FIELD 
     The present invention relates to a connector and particularly, but not exclusively, to a connector comprising a male element received within a female element and friction based locking means disposed between them. 
     BACKGROUND OF THE INVENTION 
     In a known connector of the above type, the locking means comprise machined grooves circumferentially spaced around the male element in which locking balls retained in a cage surrounding the male element are adapted to run. The balls are forced out into contact with the female element when the male element is received therein and applying a tension load to the two elements causes the balls to grip the female element more tightly. 
     Under certain conditions, the connector may be subject to a decrease, or complete removal of the tension load, that is normally present. In this instance, and assuming the connector is in a near vertical state, its own self weight could cause it to return to the same condition as when it was at the point of insertion. If the tension load was suddenly reapplied it could cause displacement between the male element and the female elements. 
     Where the connector is being used as a subsea connector and the female element is mounted on a mud mat, it is usual for the female element to be allowed to pivot in one axis, with respect to the mud mat base. This is to allow displacement of the mud mat base, with respect to the connector, to compensate for the unevenness of the sea bed. The connector may be subject to a decrease or complete removal, of the tension load that is normally present. In this instance, the mud mat and attached connector, which is normally suspended above the seabed could fall back to the seabed. Because of the weight of connector and attached links, it could cause the connector to pivot downward. 
     If there was a failure of the cage that maintains displacement with respect to the body, on complete removal of the tension load, this could allow its own weight to cause it to return to the same condition as when it was inserted. This could be followed by the connector pivoting downward, which could cause displacement between the male element and female element, 
     It is an object of the invention to overcome these potential disadvantages. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a connector comprising a first connector element and a second connector element, first releasable locking means disposed between the connector elements enabling the elements to be connected together and second locking means operative to prevent relative movement between the elements in a locking release direction of the first releasable locking means to prevent unlocking when a load applied to the connector is removed. 
     In a preferred embodiment of the invention, the first connector element is a male connector element and the second connector element is a female connector element adapted to receive the first connector element. The first releasable locking means advantageously comprises a cage in which a plurality of balls are retained for movement in a row of respective tapered grooves circumferentially spaced around the male connector element. As the male element is inserted into the female element, the balls are wedged between the two to lock them together. Application of a tension load to the elements increases the force with which the balls are gripped between the two elements and therefore the force connecting the two elements together. The second locking means advantageously comprises one or more lock balls retained in an apertured body disposed between the first and second elements. Means are provided enabling independent movement of the lock balls. These means comprise a cylindrical body which coaxially surrounds the cage of the first locking means and also comprises apertures through which respective lock ball(s) of the second locking means extend(s). The cylindrical body is urged towards the bore of the second connector element by resilient means, advantageously a compression spring. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which: 
         FIG. 1  shows a view in part longitudinal section of a connector; 
         FIG. 2  shows a view in section of part of the connector of  FIG. 1  to a larger scale; 
         FIG. 3  shows a view in section of that part of the connector shown in  FIG. 2  but in a different operational state, and 
         FIG. 4  shows a view in section of that part of the connector shown in  FIGS. 2 and 3  but in a different operational state. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , the connector comprises a female element  1 , defining a parallel bore  2  adapted to receive a male element  3 . The connector is intended for a subsea connection but may be employed in other areas. The male element  3  comprises a body  4  into which a plurality of circumferential rows of axially extending tapered slots are machined. A plurality of balls  5  retained in a cylindrical cage  6  are disposed in respective slots for movement up and down those respective slots. The cage  6  comprises a plurality of rows of counterbored holes  7  corresponding to respective rows of tapered slots machined in the body  4 . The diameter of these counterbored holes  7  is such as to permit corresponding balls  5  to protrude therethrough. The cage  6  is sprung with respect to the body  4 . This causes movement of the cage  6  with respect to the body  4  which causes movement of the balls  5  up and down the tapered slots and protrusion of the balls  5  through corresponding holes  7  to a greater or lesser degree. 
     The male element  3  has a padeye or clevis  8  at its end remote from the female element  1 . This padeye or clevis  8  enables attachment via chain links. Shackles or similar (not shown) to a chain, wire, synthetic rope or similar (also not shown). This latter, in turn, may be attached to, for example, an oil rig in the case of the connector being used as a subsea connection. Other types of attachment may be used. Similarly, the female element  1  also comprises a padeye or clevis  9  enabling attachment via chain links, shackles or similar to chain, wire, synthetic rope or similar (also not shown). This in turn may be attached to a suction pile driven into the seabed in the case of a subsea connection. Other types of attachment may be used. 
     Referring additionally to  FIG. 2 , the cylindrical cage  6  also comprises a plurality of circumferentially spaced longitudinally extending slots  10  through which respective lock balls  11  extend to contact the male element  3 . A cylindrical body  12  coaxially surrounds cage  6  and is connected thereto by means of an internal screwthreaded portion  13   a  on the body  12  and a complementary externally screwthreaded portion  13   b  on the cage  6 . The body  12  defines a row of circumferentially spaced holes  14  through which respective balls  11  extend. On its face remote from the screwthread  13   a , a taper  15  is formed which leads to a radiused portion  16 . A further cylindrical body  16  coaxially surrounds the male element  3  and the cage  6  to which it is connected by means of complementary respective internal and external screwthreaded portions  17   a  and  17   b  on the body  16  and the cage  6 . Seals  18  and  19  are housed in grooves formed in the body  16 . 
     A further cylindrical body  20  coaxially surrounds cage  6 . This body  20  comprises a row of circumferentially spaced holes  21  through which respective balls  11  extend to enable independent movement of those balls  10 . A further cylindrical body  22  coaxially surrounds body  20  and body  16 . This body  22  comprises a row of circumferentially spaced internally counterbored holes  24  to retain respective ones of a plurality of lock balls  23  having a diameter less than that of the diameter of balls  11 . Compression springs  24  and  25  are provided. Spring  24  is constrained to act between abutment faces on bodies  16  and  22  and spring  25  is constrained to act between abutment faces on bodies  16  and  20 . 
     Moving from right to left in  FIG. 2 , the parallel bore  2  in female element  1  leads to a parallel counterbore  26  which accommodates cylindrical body  12 , a tapered bore  27  accepting balls  11 , a recessed bore  28  accepting balls  23  and a parallel bore  29  accepting body  22 . To retain body  22  in a retained relative position to body  16  a pin  30  extends through a bore  31  in body  22  and into a recess  32  in body  16 . A seal  33  is disposed in a groove in body  22  to act between that body and element  1 . 
     In operation, pre-deployment, the body  22 , which constitutes an outer sleeve, is retained relative to body  16  which constitutes a sleeve housing for seals  18  and  19 , by retaining pin  30 . Body  22  in turn retains body  20  through abutment of the complementary steps  34  and  35  formed on bodies  22  and  20  and locks ball  11  and  23  are also held in a retracted state. 
     To make the connection, the male element  3  is inserted into the female element  1 . The balls  5  which protrude through the cage  6 , make contact with the wall of bore  24 , the female element  1 . As insertion continues, the balls  5  start to roll down respective corresponding tapered slots, carrying the sprung loaded cage  6  with them. When the balls  5  have moved sufficiently, to conform to the diameter of the female element bore  2 , the male element  3  continues to slide into full engagement. The sprung loaded cage  6  ensures contact between the balls  5  and the bore  1  is maintained. 
     Once the connection is made, as a tension load is applied to the connector, the male element  3  starts to move slightly with respect to the female element  1 , causing the balls  5 , which are in contact with the wall of the female element bore  2 , to roll up respective tapered slots, thus gripping the wall of the bore. As the tension load is increased, the grip load is also increased, thereby making a firm connection. 
     Following insertion of the male element  3  into the female element  1 , to connect the two elements the pin  30  is removed. Stored energy in springs  24  and  25  is released causing linear displacement of body  22  and body  20  with respect to body  16  as shown in  FIG. 3 . 
     Displacement of body  22  causes radial displacement of lock balls  23 , up the taper  15  on the face of body  12 , thereby engaging lock balls  23  into the recessed bore  28  in element  1 . At the same time, displacement of body  20  causes linear displacement of lock balls  11 , thereby causing engagement of lock balls  11  in the tapered bore  27  in element  1  and the adjacent diameter of male connector  3  as shown in  FIG. 4 . As a tension load is applied to the connector a firm connection is made between the male element and the female elements  3  and  1 . This causes a small linear displacement of the male element  3  as it begins to grip, with respect to the female element  1 . This displacement acts also on cage  6 , body  16 , body  12 , lock balls  23 , body  22 , spring  24  and spring  25 . As this linear displacement occurs, the lock balls  23  are allowed freedom to move longitudinally, along recessed bore  28  in element  1 . Despite this linear displacement, the energy in spring  25 , acting in the opposite direction, on body  20  maintains engagement of lock balls  11 , to the taper bore  27  in element  1  and the adjacent diameter of element  3 . 
     Lock balls  11  being engaged between the taper bore in element  1 , and the adjacent diameter of element  3  generates a unilateral gripping force preventing inward linear displacement of element  3 , with respect to element  1 , but still allowing free outward linear displacement of element  3  with respect to element  1 . 
     It will be appreciated that the above embodiments have been described by way of example only and that many variations are possible within the scope of the invention. For example, pin  30  and the associated apertures  31  and  32  could be dispensed with. This would result in an automatic deployment obviating the need for an ROV (Remotely Operated Vehicle) to remove the pin in marine application.