Abstract:
A quick connect and quick release coupling for connecting two pipes, including a male element and a female element that are axially fitted and interlocked one inside the other and wherein a locking mechanism retains the male element in a coupled position and a temporarily retaining mechanism immobilizes the male element, after its release by the locking mechanism, in a position for flushing a pipe connected to the male element. The locking mechanism is controlled by a sleeve that slides relative to a body of the female element. When the temporarily retaining mechanism retains the male element in flushing position, it is subjected to a first force (E 1 ) derived from a pressure (P) of the fluid flowing (F) from the male element outwards and to a second force (E 2 ), opposite to the first, exerted by elastic return means which, when the pressure (P) drops to a safety threshold, moves the temporarily retaining mechanism into a position for releasing the male element from the female element.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a quick-action safety coupling for the removable connection of two lines through which a pressurized fluid flows. 
     2. Brief Description of the Related Art 
     Such a quick-action coupling conventionally comprises a male element and a female element able to mate with one inside the other. The female element is generally connected to an upstream line and is provided with a shut-off valve that the male element moves to an open position when it is fully inserted into the female element. The male element is generally connected to a downstream line. 
     From EP-A-1 006 308 it is known to use a transient retention mechanism for retaining the male element in the female element in order to prevent, during disconnection, the male element from being violently expelled out of the female element owing to the residual pressure of the fluid in the downstream line. The transient retention mechanism for retaining the male element in the female element is designed so as to be able to fully release the male element only after it has been temporarily placed in a position in which the downstream line is purged via the coupling. 
     However, in this known device, disconnecting the coupling requires two manual operations of an external sleeve in order to pass in succession from the mated configuration to the transient retention configuration and then from the transient retention configuration to the disconnected configuration. These successive operations require the operator to wait between the two actions. 
     SUMMARY OF THE INVENTION 
     It is this drawback that the invention is more particularly intended to remedy, by proposing a quick-action coupling whereby a single operation by the user is needed to pass from the mated configuration to the retention configuration and then to the disconnected configuration. 
     For this purpose, the invention relates to a quick-action safety coupling for the removable connection of two lines, namely an upstream line and a downstream line, through which a pressurized fluid flows, this coupling comprising a male element and a female element that are able to mate axially and be locked together, one inside the other, a locking mechanism capable of axially immobilizing the male element in a coupled position, a transient retention mechanism capable of immobilizing the male element, when it is released by the locking mechanism, in a position for purging the line connected to the male element, the locking mechanism being controlled by an operating sleeve sliding along a body of the female element. This coupling is characterized in that when it retains the male element in the purge position, the transient retention mechanism is subjected to a first force due to the pressure of the fluid flowing from the male element to the outside and to a second force, opposing the first force, exerted by elastic return means and tending to displace the mechanism towards a release configuration for releasing the male element, the mechanism being capable of passing from its retention configuration for retaining the male element to its release configuration for releasing the male element depending on the resultant of the abovementioned forces. 
     Thanks to the invention, the transition from the retention configuration for retaining the male element to the release configuration for releasing the male element automatically occurs as soon as the pressure of the fluid flowing from the male element to the outside reaches a low enough value, corresponding to a safety threshold. 
     According to other advantageous features of the invention:
         the transient retention mechanism comprises a transient retention ring that can move axially under the effect of the opposing actions of the abovementioned forces, which is capable of limiting a radial and centrifugal displacement of transient latching members that can be engaged in an external peripheral groove of the male element;   the transient latching members are balls capable of axial and radial movements in slots formed in the body of the female element, said slots being elongate in a direction parallel to the direction of mating of the male element in the female element;   the transient latching members are claws having a lug, which are capable of pivoting about an axis perpendicular to the axis of mating of the male element in the female element in order to pass from a configuration in which the lug is engaged in the groove of the male element to a configuration in which the lug is disengaged from this groove, and vice versa;   the operating sleeve forms with the body of the female element at least one chamber for receiving the fluid flowing from the male element to the outside, a part of the transient retention ring forming a movable wall of this chamber;   the transient retention ring includes, on its internal face, a relief, the axial displacement of the transient retention ring bringing this relief opposite the transient latching members when the male element passes from its mated position to its purge position;   the relief is disengaged from the transient latching members by the axial displacement of the transient retention ring when the resultant of the abovementioned forces displaces the ring towards the release configuration for releasing the male element;   the transient retention ring is mounted so as to move with a slight clearance in a sliding space defined between the operating sleeve and the body of the female element;   the transient retention ring also belongs to the locking mechanism; and   the transient retention ring is capable, by its axial displacement, of disengaging locking members belonging to the locking mechanism from an external peripheral groove of the male element when the latter passes from its mated position to its purge position.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the invention will become apparent in the following description of two embodiments of a quick-action coupling according to the invention, given solely by way of example and with reference to the appended drawings in which: 
         FIG. 1  is an axial section showing the general arrangement of the male and female elements of a coupling according to the invention in a configuration in which these elements are separated; 
         FIG. 2  is a section similar to  FIG. 1 , in the mated configuration of the coupling; 
         FIG. 3  is an axial section on the line III-III of  FIG. 2 ; 
         FIG. 4  is a side view of the coupling of  FIGS. 1 to 3 , along the direction of the arrow F 4  in  FIG. 2 , the sleeve of the coupling being shown in cross section; 
         FIG. 5  is a cross section on the line V-V of  FIG. 3 , showing, at II-II and III-III, the planes of section of  FIGS. 2 and 3 ; 
         FIG. 6  is an axial section similar to  FIG. 3 , showing the coupling in an intermediate configuration between the mated configuration and the retention configuration; 
         FIG. 7  is a view similar to  FIG. 4 , showing the coupling in the configuration of  FIG. 6 ; 
         FIG. 8  is an axial section similar to  FIG. 2 , showing the coupling in the configuration of  FIGS. 6 and 7 ; 
         FIG. 9  is an axial section similar to  FIG. 8 , showing the coupling in the retention configuration; and 
         FIG. 10  is an axial section similar to  FIG. 1 , showing the female element of a coupling according to a second embodiment of the invention in the configuration in which it is separated from the corresponding male element. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows schematically the elements of a coupling  1  intended for connecting two lines C 1  and C 2  through which a pressurized fluid flows. The coupling  1  comprises a male element  3  and a female element  5 , both being of overall tubular shape and mutually complementary. 
     Passing right through the male element  3  is an axial passage  31  for the pressurized fluid, said passage opening at the two ends  3 A and  3 B of the male element  3 . The line C 1 , located downstream of the coupling  1  and shown schematically by the dot-dash lines in the figures, is connected to the passage  31  at the rear end  3 A of the male element  3 . Near its front end  3 B, the male element  3  has a plug-shaped end portion  33  provided with an annular collar  35  behind which an external peripheral groove  37  is formed. 
     The female element  5  comprises a body  51  right through which passes an axial passage  511  centred on an axis X-X′ and emerging at the two ends  51 A and  51 B of the body  51 . The line C 2 , located upstream of the coupling  1  and shown schematically by the dot-dash lines in the figures, is connected to the passage  511  at the rear end  51 B of the body  51 . An O-ring  513 , intended to seal the connection of the passages  31  and  511  in the mated configuration of the coupling, is mounted in an annular groove  514  provided in the body  51 . The O-ring  513  bears against the external radial surface  33 A of the plug  33  when the element  3  is mated with the element  5 , as shown in  FIGS. 3 and 5 . A shut-off valve  515  is mounted so as to slide in the passage  511 , being able to move between an open position and a closed position. In the closed position shown in  FIG. 1 , the valve  515  is applied against a seat  517  provided in the passage  511 . In the open position illustrated in  FIGS. 2 and 3 , the valve  515  is away from the seat  517 . 
     The female element also includes an operating sleeve  53  placed around the body  51  and capable of translational movement along this body, parallel to the X-X′ axis. A ring  55  is mounted so as to slide in a space  52  bounded between the sleeve  53  and the body  51 . The ring  55  can move axially parallel to the X-X′ axis. When the female element  5  is separated from the male element  3 , as shown in  FIG. 1 , the end face  55 A of the ring  55  turned towards the end  51 A of the body  51  bears against an internal shoulder  531  of the sleeve  53 . The ring  55  includes, on its external face  55 C turned towards the sleeve  53 , a collar  551  which is subjected to the action of a compression spring  57  that tends to push it back towards the end  51 A of the body  51  and towards the shoulder  531 . The collar  551  can move in an internal annular groove  533  of the sleeve  53 . On its internal face  55 D turned towards the central axis X-X′, the ring  55  includes, near its end face  55 A, an internal collar  555  projecting towards the X-X′ axis. 
     Two needles  58  are provided in order to lock the male element  3  inside the body  51  of the female element  5  in the mated configuration shown in  FIGS. 2 to 5 . The needles  58  can move inside two oblong slots  518  made in the body  51  of the female element and inclined relative to the X-X′ axis. The slots  518  each extend along a direction D 518 , which makes an acute angle α of about 45° with the X-X′ axis. Moreover, two transient latching balls  59  are housed in two oblong slots  519  made in the body  51  of the female element, parallel to the X-X′ axis. 
     In  FIG. 1 , the female element  5  and the male element  3  are shown separated. The valve  515  can slide freely and the pressure of the fluid in the upstream line C 2  pushes it into its shut-off position. In addition, the spring  57  pushes the ring  55  against the shoulder  531  of the sleeve  53 . 
     When the male element  3  is inserted into the body  51 , the collar  35  pushes back the needles  58  radially towards the end  518 B of the slots  518  that is furthest away from the X-X′ axis. This makes the ring  55  move back against the spring  57 . At the same time, the balls  59  are pushed back radially in the slots  519  by the collar  35 . Once the collar  35  has been passed, the needles  58  can move towards the end  518 A of the slots  518  that is closest to the X-X′ axis owing to a thrust force E 0  exerted on the needles  58  by the ring  55  subjected to the action of the spring  57 . The needles  58  are then engaged in the groove  37  of the male element  3 . The needles  58  are held in place at the end  518 A of the slots  518  by the collar  551  of the ring  55 , which exerts the force E 0  on them. Likewise, the balls  59  are able to be moved radially and engage in the external peripheral groove  37  of the male element  3  after passing the collar  35 . The mated configuration shown in  FIGS. 2 to 5  is then reached. 
     When it is necessary to open the coupling  1 , that is to say to separate the male and female elements  3  and  5 , the male element  3  is unlocked from the body  51  by exerting a retraction force R on the sleeve  53 , said force being directed towards the rear of the female element  5 , i.e. towards the line C 2 , as shown in  FIGS. 6 to 8 . The sleeve  53  bears against the ring  55  via the shoulder  531  and the face  55 A in such a way that the displacement of the sleeve  53  towards the line C 2  results in a concomitant displacement of the ring  55  in the same direction. The internal collar  555  then covers the balls  59  and prevents any radial movement of these balls towards the outside of the groove  37 . 
     The ring  55  also includes housings  553  in which the needles  58  are engaged. Because of the movement of the ring  55 , the edges  553 A of the housings  553  push the needles  58  back towards the line C 2 , exerting a force E′ 0  directed towards the rear of the element  5 . This has the effect of pushing each of the needles  58  towards the end  518 B of the corresponding slot  518 . Owing to the inclination of the slots  518 , the needles  58  are thus extracted from the groove  37 , in such a way that the male element  3  can be slightly expelled towards the outside of the body  51 , with a translational movement represented by the arrow T in  FIGS. 6 to 8 . 
     The end  3 B of the male element  3  therefore no longer bears against the valve  515 . The valve  515  is therefore pressed against the seat  517  under the effect of the pressure in the line C 2 . 
     In the position shown in  FIGS. 6 to 9 , the male element  3  is retained inside the body  51  by the balls  59  which are held in the groove  37  by the collar  555 . 
     By passing from the mated position shown in  FIGS. 2 to 5  to the retention configuration shown in  FIG. 9 , the male element  3  reaches a position in which the fluid contained in the line C 1  is purged, since the end  3 B of the male element  3  is separated from the valve  515  by a non-zero distance d. The arrows F in  FIG. 9  show the flow of the fluid from the male element  3  towards the outside. 
     In the retention configuration shown in  FIG. 9 , the fluid escapes from the male element  3  into a fluid-receiving chamber  54  provided between the sleeve  53  and the body  51 , the end  55 A of the ring  55  forming a movable wall of the chamber  54 . Thus, the ring  55  is subjected to the opposing actions of the force E 1 , due to the pressure P in the chamber  54  of the fluid flowing from the male element  3 , which tends to move the ring  55  towards the end  51 B of the body  51 , and the elastic return force E 2  of the spring  57 , which tends to move the ring  55  towards the end  51 A of the body  51 . At the same time, the pressure P in the chamber  54  moves the sleeve  53  back towards the end  51 A. When the pressure P in the chamber  54  drops because the fluid flows to the outside through the interstices forming the gaps needed to operate the coupling, the force E 2  becomes greater than the force E 1  and the resultant of the forces E 1  and E 2  pushes the ring  55  towards the end  51 A of the body  51 . Thus, the collar  555  is disengaged from the balls  59 . The balls  59  can then move radially in the slots  519  and be disengaged from the groove  37 . When the balls  59  are extracted from the groove  37 , and since the needles  58  are already upstream of the collar  35 , nothing prevents the male element  3  from being extracted from the body  51 . The coupling can then pass to the disconnected configuration shown in  FIG. 1 . 
     Thus, a single action R on the sleeve  53  allows the locking needles  58  to be disengaged, the transient retention balls  59  being covered by the ring  55 , which is held in this position by the purge pressure P against the spring  57  as long as this pressure is sufficient for the force E 1  to oppose the force E 2 . When the pressure P reaches a safety threshold that depends on the stiffness constant of the spring  57  and may be chosen by the designer of the coupling  1 , the spring  57  pushes back the ring  55  and the balls  59  release the male element  3 . 
     A coupling according to the invention is therefore a compact and single-action coupling that is simple to use and can be adapted to most male end-fittings on the market. In addition, the duration of the purge is automatically matched to the amount of fluid to be removed, unlike in dual-action couplings. The invention therefore makes it possible to save time and to improve safety. 
     In the second embodiment shown in  FIG. 10 , the elements similar to those of the first embodiment are indicated by identical references. Temporary latching balls  59  have been replaced with claws  59 ′, each having a lug  59 ′ a  capable of engaging in the external peripheral groove  37  of the male element  3 . The claws  59 ′ are mounted in a recess  52 ′ of the body  51 , each pivoting about an axis Y 59  perpendicular to the X-X′ axis. Upon passing from the mated configuration to the retention configuration, the axial displacement of the ring  55  brings its collar  555  into contact with the lugs  59 ′ a  of the claws  59 ′. Thus, any radial movement of the claws  59 ′ towards the outside of the groove  37  is prevented, thereby keeping the male element  3  in the body  51 . When the pressure P of the fluid being purged becomes low enough, the spring  57  pushes the ring  55  back towards the end  51 A of the body  51 . The collar  555  is then offset relative to the lugs  59 ′ a  of the claws  59 ′. The claws  59 ′ can then move radially so as to be disengaged from the groove  37  and to release the male element  3  from the body  51 . 
     In the two embodiments described, the locking members are needles. However, other locking members may be envisaged, especially balls or claws.