Abstract:
A female coupling element includes two superposed coaxial rings, a locking ring and safety ring which are rotatably mounted about a body of the coupling element. The locking ring is axially immobilized with respect to the body while the safety ring is able to slide with respect to the locking ring and with the body. The locking ring ( 2 ) has at least one locking slot for receiving a projection of a second element inserted within the coupling element and a notch to lock the projection axially with respect to the coupling element, and the safety ring includes at least one safety slot having a notch which locks the projection circumferentially in the notch of the locking ring.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a coupling element and to a coupling intended for removably joining two pipes. 
   2. Brief Description of the Related Art 
   EP-A-1 164 327 teaches the connecting of two elements of a coupling using locking ramps with over-travel formed in a ring of a first element and intended to accept radially projecting lugs of the second element. The two elements of the coupling comprise shut-off valves associated with springs, which tend to push the elements apart. The locking is obtained by pushing the elements closer together against the action of the valve springs until an over-travel zone is reached in which the valve springs push the lugs of the second elements into notches. In this device, the lugs are locked exclusively by the valve springs. As a result, there is a risk that the elements will become disconnected if the pressure in the fluid circuits coupled drops and there is at the same time a relative rotation of the elements, for example under the effect of vibrations, tending to cause the two elements to move closer together and to drive the lugs into the over-travel zones of the locking ramps, in the unlocking direction. 
   FR-A-1 580 284 also teaches the coupling of male and female elements using a slit ring mounted with the possibility of rotating about a body of the female element. The slit ring comprises two juxtaposed series of slits, a first series of slits being intended to accept radially projecting tenons of the male element, while the second series of slits is intended to accept internal lugs of an outer ring that fits over the slit ring. The two series of slits are arranged in such a way that the slit ring is made to rotate about the body of the female element when the male and female elements are moved axially closer together. By rotating the slit ring it is possible simultaneously to lock the tenons of the male element in circumferential notches of the first series of slits and the internal lugs of the outer ring in inclined notches of the second series of slits. In this device, introducing the tenons of the male element into the first series of slits entails aligning these slits with axial slits in the body of the female element. Now, as the slit ring is mounted with freedom to rotate about the body of the female element, these slits are liable to become shifted relative to one another. They can be aligned by exerting a backward force on the outer ring beforehand, against the action of a spring. The locking of the male and female elements is therefore not automatic. 
   Elsewhere, U.S. Pat. No. 5,253,716 describes a female coupling element comprising two superposed rings including an inner ring welded to a body of the female element and an outer ring able to move axially with respect to the inner ring. The inner ring comprises slits for accommodating radially projecting lugs of a male element able to be pushed into the female element, each lug being designed to be secured in a slit of the inner ring by means of a corresponding semicircular slot in the outer ring. In this device, connecting the male and female elements entails moving the outer ring back with respect to the inner ring and rotating the male element with respect to the female element in order to cause the lugs of the male element to travel along the slits in the inner ring. A device such as this does not allow the coupling elements to be locked automatically in a single movement on the part of an operator. 
   BRIEF SUMMARY OF THE INVENTION 
   It is these disadvantages that the invention most specifically intends to overcome by proposing a coupling element able to have a second element pushed into it, these elements being able to be locked reliably one relative to the other, the locking in the connected position occurring automatically. 
   To this end, a subject of the invention is a coupling element intended for removably joining pipes, this element being able to have, pushed into it along its longitudinal axis, a second element, the first element comprising two superposed coaxial rings, namely a locking ring and a safety ring which are mounted around a body of the first element, means being able to block the locking ring axially with respect to the body while the safety ring is able to slide with respect to the locking ring and with respect to the body, the locking ring being equipped with at least one locking slot intended to accept a radially projecting part of a second element pushed into the first element, a notch of the locking slot being able to lock the radially projecting part axially with respect to the first element, the safety ring being equipped with at least one safety slot intended to accept the radially projecting part when it is accepted in the locking slot, a notch of the safety slot being able to lock the radially projecting part circumferentially with respect to the locking ring in the notch of the safety slot, characterized in that the locking ring and the safety ring are mounted with the possibility of rotating about the body of the element, means being able to cause the two rings to rotate as one. 
   According to other advantageous features of a coupling element according to the invention:
         the locking ring is the inner ring while the safety ring is the outer ring;   the notch of the locking slot is directed substantially circumferentially with respect to the element while the notch of the safety slot is directed substantially axially with respect to the element;   the means for causing the locking ring and the safety ring to rotate as one comprise at least one member projecting radially from the outer surface of the inner ring and able to be housed in an axial slit of the outer ring;   the means for axially blocking the locking ring with respect to the body comprise at least one member projecting radially from the inner surface of the locking ring and able to be housed in an outer peripheral groove of the body;   the locking slot comprises an entry portion directed substantially axially with respect to the element;   the element comprises elastic return means which tend to position the safety ring with respect to the locking ring in such a way that the notch of the locking slot and the notch of the safety slot are substantially superposed;   the safety slot comprises an entry portion, one edge of which is inclined from the notch of the safety slot towards the entry portion of the locking slot, this edge being intended to guide the radially projecting part of a second coupling element pushed into the first element out of the notch of the locking slot when the coupling elements are being disconnected;   the safety slot comprises an entry portion, a second edge of which is inclined from the notch of the safety slot towards the entry portion of the locking slot, this second edge being intended to guide the radially projecting part of a second coupling element towards the notch of the locking slot when the coupling elements are being connected.       

   Another subject of the invention is a coupling for removably joining pipes, comprising a first element and a second element which are able to be pushed one into the other along a main axis of the coupling, the second element comprising at least one radially projecting part while the first element is as described hereinabove. Advantageously, the second element comprises at least two radially projecting parts, the first element comprising at least two corresponding locking slots and at least two corresponding safety slots. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The features and advantages of the invention will become apparent from the description which will follow of two embodiments of a coupling element and of a coupling according to the invention, which description is given purely by way of example and made with reference to the attached drawings in which: 
       FIG. 1  is a side view of a coupling according to a first embodiment of the invention, before its male and female elements are coupled; 
       FIG. 2  is a view similar to  FIG. 1  during a first step in the coupling of the male and female elements; 
       FIG. 3  is an axial section on a larger scale on the line III-III of  FIG. 2 ; 
       FIG. 4  is a view similar to  FIG. 1  during a second step in the coupling of the male and female elements; 
       FIG. 5  is an axial section on the line V-V of  FIG. 4 ; 
       FIG. 6  is a view similar to  FIG. 1  during a third step in the coupling of the male and female elements; 
       FIG. 7  is a view similar to  FIG. 1  when the coupling is in the locked configuration able to allow fluid to pass; 
       FIG. 8  is a view similar to  FIG. 1  during a first step in the uncoupling of the male and female elements; 
       FIG. 9  is a section similar to  FIG. 3  for a coupling according to a second embodiment of the invention, the internal valves of the coupling elements having been omitted. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The coupling according to the first embodiment of the invention, depicted in  FIGS. 1 to 8 , comprises a female element A and a male element B, both of tubular overall shape and complementing one another. The rear part of the female element A is fluidically coupled to a first pipe C 1 , while the rear part of the male element B is coupled to a second pipe C 2 . 
   The main axis of the coupling formed by the elements A and B, that is to say the longitudinal axis of the elements A and B in the configurations they adopt in  FIGS. 1 to 8 , is denoted X-X′. 
   The female element A has a body  1  which is tubular overall and of circular cross section, around which are mounted two rings of circular cross section, these being coaxial and superposed, namely an inner locking ring  2  and an outer safety ring  4 , centred on the axis X-X′. 
   The male element B comprises a body  5  which is tubular overall and of circular cross section and comprises, near its front end  5 A, which is the opposite end to the pipe C 2 , a pair of diametrically opposed lugs  51  which project radially outwards. 
   As shown in  FIG. 3 , a pushrod  53  is designed to be mounted fixedly inside the body  5  centred on the axis X-X′. An annular valve shutter  55  is positioned around the pushrod  53  and elastically loaded by a spring  54  towards a seat  57  formed inside the body  5 . There are two seals  58  and  59 , one of them providing sealing between the valve shutter  55  and the pushrod  53  and the other providing sealing between the valve shutter  55  and the body  5 . 
   The body  1  of the female element A defines an inner radial shoulder  11  against which a spring  14  can bear, this spring exerting an elastic force on a valve shutter  15  so as to press it onto a seat  17  formed in the body  1 . A seal  19  mounted on the valve shutter  15  provides sealing between this valve shutter and the body  1 . 
   The locking ring  2  and the safety ring  4  of the female element A are able to turn with respect to the axis X-X′ about the body  1 . The inner ring  2  is provided with two diametrically opposed pegs  21  which project radially with respect to the inner ring  2  both inwards and outwards. An inner end  21 A of each peg  21  is intended to be in an outer peripheral groove  12  of the body  1 . Thus, the inner locking ring  2  is axially blocked with respect to the body  1 . 
   The pegs  21  are able to slide via their outer ends  21 B in two diametrically opposed axial slits  41  formed in the outer safety ring  4 . Because of the collaboration between the pegs  21  and the slits  41 , the inner locking ring  2  and the outer safety ring  4  rotate as one about the body  1 , the safety ring  4  being able to move in terms of axial sliding with respect to the locking ring  2  and with respect to the body  1 . 
   The locking ring  2  comprises two diametrically opposed locking slots  23  intended to accept the lugs  51  of the male element B. Each slot  23  is open-ended and extends from an opening  25  formed at the front end  2 A of the locking ring  2  which is the opposite end to the pipe C 1 . Each opening  25  is provided with two lateral entry chamfers  251  designed to make it easier to couple the elements A and B by guiding the lugs  51 . Each slot  23  comprises a substantially axial entry portion  23 A and a substantially circumferential notch  23 B, that is to say a notch directed in a direction that corresponds to a rotation about the axis X-X′, which constitutes the opposite end of the locking slot  23  to the opening  25 . The entry portion  23 A is bounded by walls  231  and  233  which are substantially parallel to the axis X-X′. 
   The safety ring  4  comprises two diametrically opposed safety slots  43  intended to accept the lugs  51  of the male element B when they are housed in the locking slots  23  of the locking ring  2 . For this purpose, the lugs  51  are designed to have a height such that they can engage both with the inner locking ring  2  at the locking slots  23  and partially with the thickness of the outer safety ring  4  at the safety slots  43 . The fact that the lugs  51  do not penetrate the entire thickness of the safety ring  4  improves the mechanical integrity of this ring. This is because it becomes possible to provide material in the outermost thickness of each slot  43 . In the embodiment described, each slot  43  is open, except at the front end  4 A of the ring  4  which is the opposite end to the pipe C 1 , where entry to the slot  43  is defined by a non-open inner end part  45  of the ring  4 . As an alternative, each slot  43  could be not open over its entire length. 
   Each safety slot  43  comprises an entry portion  43 A and a substantially axial notch  43 B which constitutes the opposite end of the slot  43  to the end part  45 . The entry portion  43 A is inclined at an obtuse angle α with respect to the notch  43 B and is defined by parallel walls  431  and  433 . 
   A compression spring  3  is positioned between an outer radial shoulder  27  of the inner locking ring  2  and an inner radial shoulder  47  of the outer safety ring  4 . The spring  3  exerts an elastic force on the safety ring  4  and pushes it away from the pipe C 1 . The elastic force due to the spring  3  positions the safety ring  4  in such a way that each notch  23 B of a locking slot is substantially superposed with a notch  43 B of a safety slot, while each opening  25  of a locking slot is substantially superposed with an end part  45  of a safety slot. Thus, by virtue of the spring  3 , there is no stable relative position of the rings  2  and  4  that does not allow the male element B to be pushed into the female element A. 
   When the male element B is to be pushed into the female element A, these elements are brought closer together as depicted by the arrows F 1 , in  FIGS. 1 to 5 . Each lug  51  of the male element B is introduced simultaneously into the opening  25  of a locking slot  23  of the locking ring  2  and into an end part  45  of a safety slot  43  of the safety ring  4 . Under the effect of the axial forces F 1 , each lug  51  progresses axially in the entry portion  23 A of the slot  23  until it comes elastically into abutment against the inclined edge  433  of the entry portion  43 A of the slot  43 . This inclined elastic abutment causes the safety ring  4 , and therefore the locking ring  2 , to rotate slightly in the direction of the arrow R 1  of  FIG. 2 , making it possible to compensate for any slack there might be between the lug  51  and the edge  231  of the portion  23 A of the slot  23 . 
   Under the action of the forces F 1  sustained by the elements A and B, the lug  51  continues to progress along the portion  23 A, bearing against the edge  231 , the safety ring  4  being moved axially with respect to the locking ring  2  against the action of the elastic force of the spring  3 , because the lug  51  is butting against the edge  433  of the portion  43 A near the end part  45 . 
   When, in the entry portion  23 A, the lug  51  comes to face the notch  23 B in the locking slot  23 , the locking ring  2  and the safety ring  4  are able to turn with respect to the axis X-X′ about the body  1 . This rotation takes place by virtue of the axial forces F 1  sustained by the elements A and B. Because of the inclination of the wall  433  of the slot  43  with respect to the axis X-X′ of the coupling, abutment of the lug  51  against the wall  433  causes the safety ring  4 , and therefore the locking ring  2 , to move laterally and this causes them to turn about the body  1  in the direction of the arrow R 1  of  FIG. 4 . Thus, the notch  23 B of the locking slot  23  comes to surround the lug  51  partially and locks its position axially as can be seen in  FIG. 6 . 
   When the locking ring  2  and safety ring  4  have finished rotating, each lug  51  lies, in the entry portion  43 A, facing the notch  43 B of the safety slot  43 . As the notch  43 B is substantially axial, the safety ring  4  is then able to slide with respect to the locking ring  2  and with respect to the body  1  under the elastic action of the spring  3 . The notch  43 B of the safety slot  43  thus comes to surround the lug  51  partially and locks its position circumferentially, that is to say in terms of rotation about the axis X-X′, with respect to the notch  23 B as can be seen in  FIG. 7 . When the coupling of the male B and female A elements is complete, each lug  51  is therefore in a locked position in the two notches  23 B and  43 B, the locking ring  2  impeding any axial movement of the lug  51  and one lateral movement of the lug  51  by virtue of the closed end of the notch  23 B, while the safety ring  4  impedes the remaining lateral movement of the lug  51  out of the notch  23 B. 
   As described hereinabove, the locking of the lugs  51  in the locking slots  23  and safety slots  43  is essentially axial and automatic. When the male element B and female element A are in the coupled configuration, these elements are able to pivot with respect to one another. Thus, the coupling does not introduce any stress in the event that the pipes become twisted. 
   The male element B and female element A of the coupling according to this first embodiment of the invention are uncoupled by exerting on the outer safety ring  4  an axial force towards the pipe C 1  against the action of the spring  3  as depicted by the arrow F 2  in  FIG. 7 . The inclined edge  431  of the entry portion  43 A of the slot  43  then comes into abutment against the lug  51 . The inclined edge  431  exerts a circumferential component of force on the lug  51  and this guides the lug  51  out of the notch  23 B of the locking slot  23  as far as the entry portion  23 A. When the lug  51  is in the entry portion  23 A of the locking slot  23 , the safety ring  4 , released by the operator, is able to be moved away from the pipe C 1  under the action of the spring  3 . Under the elastic action of the safety ring  4  and of the valve shutters  15  and  55 , the lug  51  is pushed back towards the opening  25  until it is ejected from the locking ring  2 . The male B and female A elements of the coupling are then disconnected. Optionally, an additional force may be exerted by an operator in order to disconnect the elements A and B. 
   Particularly advantageously, the edge  431  of the entry portion  43 A of the safety slot  43  is inclined towards the entry portion  23 A of the locking slot  23  and opens into the entry portion  23 A irrespective of the relative axial position of the rings  2  and  4 . Thus, when uncoupling the elements A and B, the edge  431  guides the circumferential movement of the lug  51  out of the notch  23 B and guarantees that the lug  51  can actually reach the entry portion  23 A before the operator releases the safety ring  4 . Since the edge  431  guides the lug  51  out of the notch  23 B, disconnection entails no further intervention on the part of the operator for moving the lug  51  circumferentially. 
   The disconnecting of the male B and female A elements of the coupling of the invention is therefore a disconnection in a single movement, this single movement corresponding to the axial moving of the safety ring  4  towards the pipe C 1 . If the male element B is not fully locked in the female element A, that is to say if the lug  51  has not engaged in the notch  23 B of the locking slot  23 , the safety ring  4  and the elastically loaded valve shutters  15  and  55  push the lug  51  out of the locking slot  23  and disconnect the male and female elements. Thus, any intermediate position between the unlocked state and the locked state, or between the locked state and the unlocked state, is impossible. 
   By virtue of the twofold, axial and circumferential, locking of the lugs  51  in the notches  23 B and  43 B, any risk of the male and female elements becoming unlocked while in the connected position is eliminated. 
   When the male B and female A elements of the coupling according to the invention are being connected or disconnected, the highest forces, which correspond to the configurations in which the two elements are closest to one another, are provided by an operator rather than by the compression spring  3 . This guarantees the reliability of the locking and of the unlocking of the lugs  51  with respect to the slots  23  and  43 . In addition, because the edges  431  and  433  of the safety slots  43  are inclined, the forces supplied by the operator are very efficient, improving the ergonomics. 
   In the embodiment described, the inclined edges  431  and  433  of the slots  43  are mutually parallel. In a variant, not depicted, of the invention, the edges  431  and  433  can be non-parallel, each being inclined at an angle chosen for optimum ergonomics in the connecting and disconnecting of the elements A and B. 
   By virtue of the combination of locking slots  23  and safety slots  43 , the axial over-travel of the coupling according to the invention corresponds to the operating tolerance. It is therefore minimal. Hence, the axial size of the parts that make up the male B and female A elements of the coupling can be small, as can the travel and size of the internals, such as the safety valves. The rotational over-travel of the coupling of the invention is also reduced, making it possible to reduce the extent to which the parts are weakened by the creation of the slots. 
   In the second embodiment of the invention, depicted in  FIG. 9 , the female element A comprises, as in the first embodiment, a locking ring  2  and a safety ring  4  which are coaxial and mounted around the body  1 . However, unlike in the first embodiment, the locking ring  2  here is the outer ring, while the safety ring  4  is the inner ring. The outer locking ring  2  comprises an internal peripheral flange  22  intended to be housed in an outer peripheral groove  13  of the body  1 . Thus, the outer locking ring  2  is axially blocked with respect to the body  1 . The locking ring  2  and safety ring  4  respectively comprise, as they did in the first embodiment, two locking slots  23  and two safety slots  43  able to accept the diametrically opposed lugs  51  of the male element B. As depicted in  FIG. 9 , the slots  23  and  43  are open-ended. As a variant, the locking slots  23  could be non open-ended. 
   The locking ring  2  and safety ring  4  are connected by two pins, not depicted, positioned substantially at right angles to axial slits, not depicted, analogous with the slits  41  of the first embodiment, formed in the locking ring  2  and safety ring  4 . The rings  2  and  4  thus rotate as one about the body  1 , the safety ring  4  being able to slide with respect to the locking ring  2  between the body  1  and the locking ring  2 . A compression spring  3 , housed between the inner safety ring  4  and the outer locking ring  2  exerts an elastic force on the safety ring  4  away from the pipe C 1  so as to substantially superpose firstly the notches of the slots  23  and  43  and secondly their openings and end parts. 
   The coupling of the male B and female A elements of the coupling according to this second embodiment is automatic, as it was in the first embodiment. The uncoupling of these elements is performed by exerting on the inner safety ring  4  an axial force directed towards the pipe C 1 , against the action of the spring  3  as depicted by the arrow F 3  in  FIG. 9 . The inner ring  4  is accessible by virtue of an outer peripheral flange  42  which is slit to allow the passage of the lugs  51  and designed to project axially with respect to the outer ring  2 , away from the pipe C 1 . As in the first embodiment, the disconnecting of the elements A and B is a disconnection involving a single movement. 
   The invention is not restricted to the examples described and depicted. According to a variant, not depicted, of the invention, the lugs  51  may be formed in a female element, these lugs projecting radially towards the inside of the tubular female element. A complementary male element would comprise a locking ring and a safety ring both analogous to the rings  2  and  4  and mounted around a body of the male element. In this case, each slot of the outer ring would have to be open-ended, even at the front end of this ring, to allow the corresponding lug to pass. The slots in the inner ring would not need to be open-ended. 
   According to another undepicted variant of the invention, the number of lugs  51  may be higher than two, the lugs advantageously being uniformly distributed over the surface of the element equipped therewith. It may also be advantageous, when there are several lugs  51 , to have these lugs not uniformly distributed, and likewise the corresponding locking slots  23  and safety slots  43 . The coupling obtained would thus have polarizing means, contributing to making the coupling more safe. 
   Furthermore, each lug  51  may not form an integral part of the body  5  but be attached to this body and immobilized by any appropriate means. Each lug  51  could equally be provided with a flat so as to spread the contact loads resulting from the action of the valve springs, in the notch  23 B of the corresponding locking slot. As an alternative, this notch  23 B could be designed with an arc-shaped arrangement a few tenths of a millimeter deep so as to prevent hammering of the contact surfaces which occurs when a cylindrical lug  51  is mated with a flat-walled notch  23 B. 
   Finally, in the embodiment described, the clearances there are between each lug  51  and the notch  23 B of the corresponding locking slot are not compensated. As an alternative, these clearances could be compensated by the safety ring  4  in the axial and lateral directions using an appropriately rated spring. Circumferential, or lateral, locking of each lug  51  in the position in which the male and female elements are connected may also be provided exclusively by the safety ring  4 , through suitable configuration of this ring. In this case, the locking ring  2  merely locks each lug  51  in the axial direction.