The present invention relates to a ball coupler suitable for use, in particular in circuits for conveying fluid under pressure, in order to provide quick coupling between two circuit elements such as a hose and a member for delivering or receiving fluid, or to hoses. 
   More particularly, the couplings concerned are of the type described in document FR-A-2 786 848. 
   BACKGROUND OF THE INVENTION 
   Ball couplers are known that comprise a male tubular endpiece presenting an outer annular flange with a groove defined behind the flange, and a female tubular endpiece for receiving the male tubular endpiece, the endpieces being designed to be associated with respective elements of the circuit. The male endpiece is held in the female endpiece by locking means that act on balls that are received in the groove behind the annular flange. In general, the locking means comprise a ball-retaining cage mounted via one end on the female endpiece so as to extend beyond the female endpiece, and a grip mounted on the retaining cage so as to be capable of being turned between first and second positions. The grip has internal camming surfaces that are angularly offset relative to one anther and that are arranged so that when the grip is in its first position, the balls are held projecting into the inside of the retaining cage so as to retain the annular flange of the male endpiece, and when the grip is in its second position, the balls are released radially and can be taken to a retracted position, thereby releasing the flange and enabling the male endpiece to be extracted from the female endpiece. 
   Thus, the coupling is unlocked by causing the grip to turn relative to the sleeve. The risk of such a movement being of accidental origin is limited and this constitutes one of the main advantages of a coupler of this type, since the probability of the coupler being unlocked in untimely manner is small. 
   The above-mentioned document describes two main embodiments. One of them is an embodiment without a valve member for closing the duct, with the connection being undone while still connected to a source of fluid under pressure. The other includes a valve member, which thus opens when the connection is made and closes when the connection is undone. In that second embodiment, there is a variant in which disconnection takes place in two stages: a first stage during which the valve member is closed and the hose downstream from the connection (downstream relative to the source of fluid under pressure) is purged, and a second stage during which the physical separation of the connection is completed, but without there being any pressure in the connection. 
   In those embodiments, means are described for returning the grip into a position in which it locks the connection, i.e. a position in which the flange cannot be extracted because it is not possible for the blocking balls to be pushed back radially by the flange during such a movement. This is also the position in which the blocking means are to be found when there is no male endpiece, which position does not act in all of the embodiments described to prevent a connection being made. 
   The invention relates specifically to a ball coupler in any of the above-mentioned variants in which the grip-return means are improved so as to be even more robust and less expensive to fabricate for a more sophisticated coupler. 
   SUMMARY OF THE INVENTION 
   To this end, the invention provides a ball coupler having a longitudinal axis and comprising:
         a male tubular endpiece;   a female tubular endpiece;   a tubular sleeve extending the female endpiece and presenting slots for forming a cage for retaining balls for blocking the male endpiece in the female endpiece; and   a grip coaxial about the sleeve and mounted to turn thereon about the longitudinal axis of the coupler between at least two angular positions relative to the sleeve, the grip possessing housing means for housing each ball, which means comprise for each ball:
           a first setback facing the corresponding slot when the grip is in a first position in order to retain the ball in question in a position for blocking the connection;   a second setback offset angularly relative to the first setback and connected thereto so as to receive the blocking ball in a position for unblocking the connection when the grip is in a second position; and   resilient return means for urging the grip into its first position; which return means comprise, in the grip, a ring that is constrained to turn with the grip and that is movable axially relative thereto, said ring presenting two end surfaces, one of which faces towards a shoulder of the sleeve for slidably bearing thereagainst to co-operate in reversibly transforming turning movement of the grip into axial movement of the ring relative to said grip, and the other of which forms the bearing face for a compression spring tending to urge said ring against said shoulder.   
               

   In this configuration, the coupler is more robust. The return spring is of the well-tried compression spring type, there operates solely under stress along the direction of its axis, unlike the spring described in the above-mentioned document. 
   In a preferred embodiment of the invention, the shoulder of the sleeve presents a projection turned towards the sloping ring, with the end surface of the ring that faces the projection constituting, for said projection, an unstable bearing surface in the form of a ramp extending between two points that are axially offset relative to each other, the point of the ramp that is furthest from the shoulder being associated with an angular abutment for the projection in such a manner as to index the position of the grip and of the sleeve in spite of the constantly present resilient return force urging the grip towards the shoulder of the sleeve. The surface of the projection that is in contact with the slope is of small area and the plastics materials used ensure that friction between the projection and the ramp is very low, thereby encouraging reversibility of the movement and thus enabling a weak spring to be used. 
   In preferred manner, the coupler includes, in the grip, an annular setback into which the first setbacks open out axially in such a manner as to receive the balls in an unblocking position, and a second ring mounted in the annular setback for sliding between a position in which it releases the annular setback, and a position in which it closes it, and towards which it is urged resiliently, pushing the balls into their first setback, and the compression spring is placed between said two rings. 
   This provides a coupler in which only one spring is used and the grip is axially decoupled from the spring so that resistance to the grip being turned is due solely to the co-operation between the sloping ring and the shoulder of the sleeve, and to the forces involved therewith, independently of any interfering friction force. 
   In the variant embodiment of the coupler described in document FR-A-2 786 848 that provides for disconnection to take place in two stages, with the grip being turned in one direction and then in the other, the end surface of the ring facing towards the shoulder has two ramps adjacent to each other at the point where the grip is angularly indexed relative to the sleeve. Thus, regardless of the direction in which the grip is turned manually, it returns to the angularly-indexed position on being released. 
   Other characteristics and advantages of the invention appear from the description given below of embodiments thereof. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is made to the accompanying drawings, in which: 
       FIG. 1  is a fragmentary longitudinal section view of a coupler of the invention while it is being coupled; 
       FIG. 2  is a view identical to that of  FIG. 1 , the coupler being in a disconnection state; 
       FIG. 3  shows a second embodiment of the coupler of the invention in a similar section view; and 
       FIG. 4  is a fragmentary outside view of the  FIG. 3  coupler, the outer grip being removed. 
   


   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 1 and 2 , the ball coupler constituting a first embodiment of the invention about a longitudinal axis  1  comprises a male tubular endpiece given overall reference  2  and a female tubular endpiece given overall reference  3 . The male tubular endpiece has an outer annular flange  4  with converging side walls  4 . 1  and  4 . 2 . The male endpiece  2  is designed to be mounted on a hose and to be inserted in the female endpiece  3 . The female endpiece  3  includes an O-ring  5  for sealing its coupling with the male endpiece  2 . The female endpiece  3  is designed to be mounted on another hose or on a member that is to be fed with fluid under pressure. 
   The ball coupler also includes a sleeve given overall reference  6  mounted via one of its ends on the female endpiece  3  so as to extend coaxially thereabout. The sleeve  6  has a portion  8  of circular inside section that is larger than the section of the annular flange  4 , and that extends beyond the female endpiece  3 . The portion  8  of the sleeve  6  presents elongate slots  10  extending parallel to the longitudinal axis  1  at 90 degrees from one another. The slots  10  possess edges  11  that converge towards each other going towards the inside of the sleeve. Balls  12  are received in the slots  10  and are of a diameter greater than the transverse dimension of the smallest opening defined by the edges  11 , such that the balls  12  cannot penetrate completely into the inside of the sleeve  6 . The sleeve  6  thus forms a cage for holding the balls  12  in the coupler. 
   A grip  13  is mounted to pivot on the sleeve  6  via two ring portions  14  projecting towards the inside of the grip  13  so as to be received in two grooves  15  formed on the outside of the sleeve  6 . The respective dimensions of the ring portions  14  and of the groove portions  15  are determined in such a manner as to enable the grip  13  to turn angularly relative to the sleeve  6  through an angle that is equal to 35 degrees, in this example. This defines first and second extreme angular positions for the grip  13  relative to the sleeve  6 . Naturally, it would be possible to provide a retaining cage having some number of slots other than four for the purpose of receiving a corresponding number of balls. 
   The grip  13  has internal means for housing the balls  12 . 
   These means comprise first setbacks  16 , each facing a portion of a slot  10  adjacent to the portion  8  of the sleeve  6  when the grip  13  is in its first position. The first setbacks  16  are of a depth that is determined in such a manner that the balls  12  received in the first setbacks  16  define a passage of section smaller than the outside section of the annular flange  4 . 
   Second setbacks  17 , angularly offset from the first setbacks  16  through an angle equal to said 35 degrees, are provided in the grip  13  and are connected to the first setbacks  16  via sloping walls. 
   It will be understood that because of the angular offset that exists between each first setback  16  and each second setback  17 , each second setback  17  extends in register with a slot  10  when the grip  13  is in its second position The depth of the second setback  17  is determined in such a manner that when the balls  12  are received in the second setback  17 , they leave a passage of section that is not less than the section of the annular flange. 
   The means for housing the balls  12  also comprise a third setback  19 . The third setback  19  is annular and it is offset axially relative to the first setback  16  so as to face the innermost portion of the slots  10  within the coupler, in the vicinity of the endpiece  3 . The third setback  19  is connected to the first setback  16  via a conical wall  20 . 
   The diameter of the third setback  19  is determined so that the balls received in said third setback  19  define a passage of section that is not less than the section of the annular flange  4 . 
   A ring  21  is mounted to slide in the third setback  19 . The ring  21  is mounted to slide between: a position in which it disengages the third setback  19  ( FIG. 1 ), with the ring  21  releasing sufficient space in the third setback  19  to receive the balls  12 ; and a position in which it closes the third setback  19  ( FIG. 2 ) into which the ring  21  is urged resiliently by a spring  24 , i.e. towards the first setbacks, pushing the balls  12  into the first setback, the spring  24  being interposed between the sleeve  6  and the ring  21 . 
   The operation of this coupler is described in document FR 2 786 848. 
   In  FIGS. 1 and 2 , it can be seen that a second ring  30  is housed in the grip  13  and the sleeve  6 . This ring  30  is constrained to turn with the grip  13  by peripheral splines  31  that co-operate with axial grooves  13   a  formed in the cylindrical inside surface of the grip  13 . The ring  30  can slide on the sleeve  6  and is subjected to the effect of a spring  32  that is placed around the sleeve  6 , in a setback  13   b  formed in the grip  13  and tending to urge the ring  30  against a shoulder  6   a  on the sleeve  6  by bearing against one of its end faces  30   a.    
   The shoulder  6   a  of this sleeve presents a projection  33  with an end  33   a  that bears against the other end face  30   b  of the ring  30 . This other face  30   b  includes a ramp  34  between two points  35  and  36  that are axially offset relative to each other, the point  36  that is further away from the shoulder  6   a  being marked by the ramp  34  and an abutment face  37  against which the projection  33  can bear laterally. This point serves to index the angular position of the grip  13  relative to the sleeve  6 . 
   In  FIG. 2 , the grip  13  has been turned relative to its position in  FIG. 1  through an angle, e.g. of 35 degrees. The housings  17  are thus facing the balls  12  such that traction exerted on the endpiece  2  to the right of the figure leads to a disconnection, the balls possessing radial clearance space in the housings  17 . When the grip is turned in this way, the ramp  34  of the ring  30  slides along the projection  33   a  and the spring  32  is compressed by virtue of the axial displacement of the ring  30  within the grip  13 . When the operator releases the grip  13 , given that the position shown is unstable, the projection  33  responds to the thrust from the spring  32  by sliding over the ramp and causing the ring  30  and thus the grip  13  to turn so as to go back to the endpiece-blocking position (if the endpiece is present), i.e. the position in which the setbacks  16  face the slots  10  and the projection  33  is in abutment against the surface  37 . 
     FIG. 3  shows some of the same elements as described above, and they are given the same references. 
   As above, the ball coupling in this embodiment has a longitudinal axis  1  and comprises a male tubular endpiece  2  and a female tubular endpiece  3 . The male tubular endpiece has an outer annular flange  4 . The female endpiece  3  is shaped in this embodiment to define a setback  40  within a tubular end member  41  having a seat  42  for a valve member  43  mounted to slide in the chamber  40  between a position in which the female endpiece is closed with the valve member  43  urged resiliently by a spring  44  against the seat  42 , and an open position in which the valve member  43  is spaced apart from the seat  42  and defines an annular flow orifice. The valve member has a tubular perforated tail  45  extending through the seat  42  from the side of the valve member that is opposite from its resilient return spring  44 . 
   As in the first embodiment, the ball coupler has a sleeve, constituted by the tubular end member  41  that is fitted on the female element  3  of the coupler and that carries the seat  42 . As before, a portion  8  of the sleeve  41  presents elongate slots  10  receiving balls  12 . The slots  10  are three in number in this embodiment and they are at 120 degree intervals from one another. 
   The portion  8  of the sleeve  41  likewise presents elongate slots  50  extending parallel to the longitudinal axis  1  and at 120 degrees from one another in alternation relative to the slots  10 . The slots  50  are longer than the slots  10  so as to extend beyond them towards the inlet end of the endpiece and they are of the same section as the slots  10 . Balls  52  are provided in the slots  50  like the balls  12  in the slots  10 . The grip  13  includes internal means for housing the balls  52 , which means are axially offset relative to the means for housing the balls  12  so as to block the balls  52  radially, or on the contrary so as to leave them radial space enabling them to be received and clear a passage for the flange  4 . It is by turning the grip in a manner similar to that used for controlling the balls  12 , that the balls  52  can be blocked in position or released. The above-mentioned document FR 2 786 848 provides a full explanation of this coupler in which two operations on the sleeve enable the portion of the circuit that is isolated by the valve member to be purged before finishing off a disconnection. 
   It is thus in a central position that the grip  13  blocks both the balls  12  and the balls  52 . A first turning operation enables the flange to pass the balls  12  while it is still retained by the balls  52 . When the grip is released, resilient return means cause it to return to its central position. A second turning operation of the grip, in the opposite direction to the first, then enables the flange to go pass the balls  52 . 
   The means for resiliently returning the grip  13  into this central zone can be seen in particular in  FIG. 4 . The sleeve  41  has a stationary outer jacket  60  that carries a shoulder  60   a  similar to the shoulder  6   a  of  FIGS. 1 and 2 . This shoulder also has a projection  61  facing towards the ring  30  that is also present in this embodiment. In  FIG. 4 , there can be seen the splines  31  of this ring that co-operate with the grip  13  so as to constrain them to turn together. The ring  30  possesses two ramps  34   a  and  34   b  extending respectively between two extreme points  35   a  and  35   b  and a change-of-direction point  36  which constitutes the indexing point for indexing the angular position of the grip  13  relative to the sleeve  41 , corresponding to said central position of the grip. A spring  62  is situated between the ring  21  and the ring  30 . This spring performs two functions: it pushes the ring  30  towards the shoulder  60   a , thereby causing the grip to be returned angularly if it is not already in its indexed position, and pushing the balls  12  and  52  into their respective slots  10  and  50  after the current connection has been made, during which the ring  21  is pushed towards the female endpiece in order to release the annular setback  19  described with reference to  FIGS. 1 and 2 . 
   This arrangement makes it possible to use only one spring, and above all it releases the grip  13  from any axial stress and from any interfering friction from a spring acting on the grip that would lead to faster wear of the parts concerned. 
   In the embodiment described, the extent to which the grip can be turned relative to the coupling is limited by the grooves and rings  14  and  15 . In the version shown in  FIGS. 3 and 4 , means can be provided between the inside surface of the grip  13  and the jacket  60  to limit the extent to which the grip can be turned, for example external portions in relief  63  on the jacket  60  engaging a spline (not shown) on the inside surface of the grip  13  which comes into abutment against one or the other portion in relief depending on the direction of rotation of the grip.
A ball coupler having a longitudinal axis and including a male tubular endpiece; a female tubular endpiece; and a tubular sleeve extending the female endpiece and presenting slots for forming a cage for retaining balls for blocking the male endpiece in the female endpiece. A grip is coaxial about the sleeve and mounted to turn about the longitudinal axis of the coupler between at least two angular positions relative to the sleeve, the grip having a housing for each ball. A resilient return device urges the grip into its first position, including in the grip, a ring that is constrained to turn with the grip and that is movable axially relative thereto.