CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a U.S. National Phase Patent Application based on International Application Serial No. PCT/EP2009/002093 filed Mar. 21, 2009, the disclosure of which is hereby explicitly incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a coupling for a connector for fluid pipes, specifically for fuel injection lines of automobiles. 
         [0004]    The invention applies in particular to a coupling for a connector for fluid pipes, comprising a female tubular base in which a male tubular end-piece is inserted in a certain axial direction to create a sealed joint, an elastically deformable blocking element for blocking the end-piece in the base when the end-piece is pushed sufficiently deep in axial direction in the base, and a locking sleeve which is mounted movable in axial direction around the blocking element in such way as to occupy a first axial position in which the blocking element is free to deform radially towards the exterior of the base and a second axial position in which it prevents the radial deformation of the blocking element. 
         [0005]    2. Description of the Related Art 
         [0006]    One known coupling for a fluid pipe connector is disclosed in WO2005/059426, in which the blocking element consists of an assembly of rigid, elastically deformable, arms arranged in tulip shape in the extension of the tubular base. When the locking sleeve occupies the first position, the arms are free to open allowing the insertion of the male end-piece in the base. Then, the arms close (returning to their rest position) in a peripheral groove of the male end-piece in order to block the end-piece in the base. In the second locking position, the sleeve surrounds the elastic arms, preventing their opening and the release of the male end-piece. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a coupling having a compact and robust design. 
         [0008]    To this end, the present invention provides a coupling for a fluid pipe connector, comprising a female tubular base in which a male tubular end-piece is inserted in a certain axial direction to create a sealed joint, an elastically deformable blocking element for blocking the end-piece in the base when the end-piece is pushed sufficiently deep in axial direction in the base, and a locking sleeve which is mounted moveable in axial direction around the blocking element in such way as to occupy a first axial position in which it leaves the blocking element free to deform radially towards the exterior of the base and a second axial position in which it prevents the radial deformation of the blocking element, characterized in that the blocking element is a C shaped rigid wire with two free extremities bent towards each other and suitable to pass through the base when the wire is radially deformed, and in that the sleeve has at least one interior radial recess in which each of the corresponding free extremities of the blocking element engages when the latter is radially deformed and the sleeve occupies said first axial position, when the sleeve occupies said second axial position, each recess is axially offset relative to the corresponding free extremity of the blocking element which prevents the radial deformation of the blocking element. 
         [0009]    The coupling according to the invention provides a quick, sealed joint between male end-piece and female base. With such a coupling arrangement, the blocking element can be locked by a short axial travel of the locking sleeve over the base; this travel corresponds approximately to the diameter of the rigid wire forming the blocking element. 
         [0010]    Advantageously, locking of the male end-piece in the female base can only occur when the male end-piece is fully inserted in the female base, which ensures that the joint is sealed. Indeed, as long as the male end-piece is only partially inserted in the female base, the blocking element will prevent the axial displacement of the locking sleeve over the base. 
         [0011]    Advantageously, a coupling for a fluid pipe connector according to the invention can have the following features:
       the rigid wire is a metallic wire, which has the advantage of good temperature resistance;   the locking sleeve has a tubular body axially extended by a leg; the leg has one free extremity which protrudes relative to the base when the sleeve occupies said first axial position and which is flush with the base when the sleeve occupies said second axial position. Advantageously, this construction provides a visual and tactile indication of the correct locking of the sleeve on the base, and therefore of the sealing of the joint;   the base has a detent which is inserted in a notch in the leg of the sleeve when the sleeve occupies said second axial position, which provides security against unexpected unlocking of the coupling;   the sleeve has a radial slot for radial insertion of said blocking element in the base so that the coupling according to the invention, consisting of three separate elements, is easy to mount.       
 
         [0016]    In one form thereof, the present invention provides a coupling for fluid pipe connector, including a female tubular base in which is inserted in a certain axial direction a male tubular end-piece to create a sealed joint, an elastically deformable blocking element for blocking the end-piece in the base when the end-piece is pushed sufficiently deep in the base in axial direction, and a locking sleeve which is mounted moveable in axial direction around the blocking element in such way as to occupy a first axial position in which it leaves the blocking element free to deform radially towards the exterior of base and a second axial position in which it prevents the radial deformation of the blocking element, characterized in that the blocking element is a C-shaped rigid metallic wire with two free extremities bent towards each other and suitable for passing through the base when the locking element is radially deformed, in that the sleeve has at least one internal radial recess in which each corresponding free extremity of the blocking element is engaged when the latter is radially deformed and the sleeve occupies the first axial position, each recess is axially offset relative to the corresponding free extremity of the blocking element when the sleeve occupies the second axial position, which prevents the radial deformation of the blocking element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0018]      FIG. 1  is a longitudinal section along axis I-I of  FIG. 2  of the connector according to the invention in the first axial position of the sleeve and when the male end-piece is partially inserted in the female base; 
           [0019]      FIG. 2  is a view of a transversal section along axis II-II of  FIG. 1  of the connector according to the invention in the same position as  FIG. 1 ; 
           [0020]      FIG. 3  is a view of a longitudinal section along axis of  FIG. 4  of the connector according to the invention in the first axial position of the sleeve and when the male end-piece is fully inserted in the female base; 
           [0021]      FIG. 4  is a view of a transversal section along axis IV-IV of  FIG. 3  of the connector according to the invention in the same position as  FIG. 3 ; 
           [0022]      FIG. 5  is a view of a longitudinal section along axis V-V o  FIG. 6  of the connector according to the invention in the second position of the sleeve; 
           [0023]      FIG. 6  is a view of a transversal section along axis VI-VI of  FIG. 5  of the connector according to the invention in the same position as  FIG. 5 ; 
           [0024]      FIG. 7  is a perspective view of the connector according to the invention in the first axial position of the sleeve and when the male end-piece is separated from the female base; 
           [0025]      FIG. 8  is a perspective view of the connector according to the invention in the second axial position of the sleeve and when the male end-piece is fully inserted in the female base; 
           [0026]      FIG. 9  is a perspective view of the connector according to the invention in another execution form, in the first axial position of the sleeve and when the male end-piece is separated from the female base; 
           [0027]      FIG. 10  is a perspective view of the connector according to the invention in another execution form, in the second axial position of the sleeve and when the male end-piece is fully inserted in the female base; 
           [0028]      FIG. 11  is a view of a transversal section along axis XI-XI of  FIG. 9  of the connector according to the invention, in the same position as  FIG. 9 ; and 
           [0029]      FIG. 12  is a view of a transversal section along axis XII-XII of  FIG. 10  of the connector according to the invention in the same position as  FIG. 10 . 
       
    
    
       [0030]    Corresponding reference characters indicate corresponding parts throughout the several views. Although the exemplifications set out herein illustrate embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed. 
       DETAILED DESCRIPTION 
       [0031]      FIG. 1  shows a fluid pipe connector  1  according to the invention comprising a coupling  2  and a male tubular end-piece  3 . 
         [0032]    Coupling  2  according to the invention comprises a female tubular base  4  in which the male tubular end-piece  3  is inserted in axial direction indicated by arrow A, an elastically deformable blocking element  5  inserted in the female base  4  and a locking sleeve  6 , in the form of a tubular body mounted around the female base  4  and the blocking element  5 , which is movable in axial direction A. 
         [0033]    In  FIG. 1 , the male end-piece  3  is shown partially inserted in the female base  4 . 
         [0034]    As shown in  FIG. 1 , the female base  4  is fitted, in its upper part opposite the opening in which the male end-piece is inserted, with two fluid lines  4 A,  4 B which must be connected with the male end-piece  3 . It is obvious that the female base  4  can be fitted with one or more than two fluid lines. 
         [0035]    Furthermore, the external wall of female base  4  can be provided advantageously with a guide groove or rib cooperating with a corresponding rib of groove (not shown) in the internal wall of the locking sleeve to facilitate the axial guiding of sleeve  6  over base  4 . 
         [0036]    The male end-piece  3  is shown in the form of a cylindrical tube with varying external diameters over its length. More particularly, it comprises an extremity length portion  3 A forming a groove with a first diameter indicated by D 1  in  FIG. 1 , this portion  3 A is intended to be inserted in the bottom of the female base  4 . An O-ring seal surrounds this portion  3 A. 
         [0037]    Portion  3 A is extended by another length portion  3 B with a diameter D 2  greater than diameter D 1 ; the two portions  3 A,  3 B are connected by an intermediate tapered portion  3 C with low slope (increasing diameter). As will be described here after, the low slope of portion  3 C allows for the progressive radial deformation, towards the exterior of base  4 , of the blocking element  5 . 
         [0038]    The male end-piece  3  has also in the immediate extension of portion  3 B, another intermediate tapered portion  3 D (decreasing diameter) which precedes a third cylindrical portion (not indicated) having a diameter smaller than D 2  but slightly larger than D 1 . The slope of portion  3 D is steeper than the slope of portion  3 C to form a sort of shoulder for the blocking element  5  as described further down. 
         [0039]    The female base  4  has an axial bore  4 C with internal diameters D 3 , D 4  complementary to external diameters D 1 , D 2  of the male end-piece  3 . When the male end-piece  3  is fully inserted in the female base  4 , the O-ring seal  7  is compressed in the bore of the female base  4  (in the portion of the bore with diameter D 3 ) in order to create a sealed joint. The bore in the base has also a tapered portion, complementary to portion  3 C of the male end-piece which serves as centering for the male end-piece in the female base. 
         [0040]      FIG. 2  shows a transversal section of connector  1  according to the invention in the same position as  FIG. 1 , which provides a better view of how the blocking element  5  is arranged in the female base  4  and in the locking sleeve  6 . 
         [0041]    Blocking element  5  is here a spring in the form of a C-shaped staple made of rigid wire, of which the two free extremities  8 A,  8 B are bent towards each other. This elastically deforming staple can be a round or flat metallic wire. The staple is mounted in coupling  2  by lateral insertion through a radial slot  9  in locking sleeve  6 , then in two lateral recesses  10 A,  10 B of base  4  so that its free bent extremities  8 A,  8 B surround the male end-piece  3  in bore  4 C. As shown in  FIG. 2 , the free extremities  8 A,  8 B of staple  5  form two symmetrical S′s; the extremities  11 A,  11 B are bent radially towards the exterior of the free extremities  8 A,  8 B and engage respectively in two corresponding internal radial recesses  12 A,  12 B of sleeve  6  and the median parts  13 A,  13 B of the free extremities  8 A,  8 B which surround the male tube. 
         [0042]    In  FIG. 2 , staple  5  is radially deformed towards the exterior of base  4  around the length portion  3 B with large diameter D 2  and the locking sleeve  6  occupies a first axial position, indicated by arrow P 1  on  FIG. 1 , in which it leaves the blocking element  5  free to deform radially towards the exterior of base  4 . At rest, the median parts  13 A,  13 B of staple  5  define a circle with internal diameter approximately equal to D 1 . 
         [0043]    In a first insertion phase of the male end-piece  3  in the female base  4 , the portion with length  3 A surrounded by seal  7  (with external diameter approximately equal to D 1 ) passes through the staple. Then, the tapered portion  3 C of the male end-piece applies a radial deformation stress on the staple which causes the ends  11 A,  11 B of extremities  8 A,  8 B to be thrust in recesses  12 A,  12 B of sleeve  6 . Then, the staple  5  surrounds the portion with length  3 B and diameter D 2 . In this deformed position, staple  5  prevents the axial displacement of sleeve  6 . The radial recesses  12 A,  12 B have a height in axial direction which is slightly greater than the height of the staple (diameter of the wire for instance) but which is less than the travel of the sleeve along this axial direction. 
         [0044]      FIGS. 3 and 4  show now the male end-piece fully inserted in the female base  4 . The tapered portion  3 D, with decreasing diameter, of the male end-piece is now facing staple  5 . Seal  7  is compressed in bore  4 C of the basis. The free extremities of the staple  8 A,  8 B are elastically returned to their retracted position (rest position) and are outside the recesses  10 A,  10 B. 
         [0045]    In its retracted position, the staple applies an axial force on the tapered portion  3 D which tends to push the male end-piece to the bottom of the bore of the female base. 
         [0046]    In  FIGS. 5 and 6 , the locking sleeve  6  is axially displaced (here towards the bottom of the base) from its initial position P 1  to a second position P 2  to axially offset the recesses  10 A,  10 B from the ends  11 A,  11 B of extremities  8 A,  8 B of staple  5 , which prevents radial deformation of staple  5  and therefore locks the male end-piece in the female base. 
         [0047]      FIGS. 7 and 8  show in perspective the connector according to the invention, respectively with the male end-piece separated from the base and with the male end-piece inserted in the base. In  FIG. 7 , the locking sleeve  6  is in its position P 1  for insertion of the male end-piece in the female base and in  FIG. 8 , the locking sleeve  6  is in its position P 2  locking the male end-piece in the female base. 
         [0048]    As shown in  FIGS. 7 and 8 , the locking sleeve  6  consists of a cylindrical section with an axially extending leg  14 . In position P 1  of the locking sleeve  6 , the free extremity  14 A of the leg  14  protrudes relative to the female base  4 . By pressing this free extremity  14 A of the leg  14  sleeve  6  is displaced from position P 1  to position P 2 . In the P 2  position of the locking sleeve  6 , the extremity  14 A of the leg  14  is flush with the female base  4 , which provides an easy tactile and visual detection to verify that the male end-piece is locked in the female base. 
         [0049]    As shown in  FIGS. 7 and 8 , the base  4  has a detent  15  in the form of a boss and leg  14  of locking sleeve  6  has a notch  17 . In position P 1  of the locking sleeve, the detent  15  is abutted against face  16  of notch  17 , blocking the displacement of sleeve  6  in axial direction A (towards the bottom of the base). In position P 2  of the locking sleeve, the detent  15  is inside notch  17 , blocking the displacement of sleeve  6  in the axial direction A (towards the top of the base). The displacement of locking sleeve  6  from position P 1  to position P 2  and inversely requires that a certain axial force is applied on leg  14 . The dimensions of detent  15  and notch  17  are adjusted to correspond to the axial travel of the sleeve between the two positions P 1  and P 2 , which is approximately equivalent to the thickness in axial direction of staple  5 . 
         [0050]      FIGS. 7 and 8  show the radial slot  9  in the sleeve which serves for installing the staple  5  in the base and also a thin slot  18  which serves for the axial positioning of the head of staple  5  in the sleeve when the locking sleeve  6  is in position P 2 . The axial distance between slots  9  and  18  is identical to the axial travel of sleeve  6  between positions P 1  and P 2 . 
         [0051]    To connect the male end-piece  3  in the female base  4  of coupling  2  according to the invention, staple  5  is elastically deformed to allow the passage of a centering diameter D 3  of the male end-piece  3 . When in contact with this diameter D 3 , staple  5  achieves the maximum flexion position. In this position, staple  5  interacts with the locking sleeve  6  by engaging in the recesses  12 A,  12 B made in sleeve  6 . The extremities  11 A,  11 B of staple  5  positioned in this way, perform the function of axial abutment for the descent of locking sleeve  6 , which guarantees mechanically that locking will take place only when the staple  5  is returned to its rest position during the passage of a smaller diameter of the end-piece  3  than the centering diameter. In this rest position, staple  5  is locked behind a shoulder  3 D of the male end-piece and the locking sleeve  6  can be blocked by an axial displacement. 
         [0052]      FIGS. 9 to 12  illustrate a variant configuration of a connector  100  according to the invention with a coupling  200  comprising a locking sleeve  6  with two legs  101 ,  102  diametrically opposed and axially offset, while leg  101  is slightly longer than leg  102 . 
         [0053]    In  FIG. 9 , the male end-piece  3  is separated from coupling  200  and the locking sleeve  6  occupies the first axial position P 1 .  FIG. 9  shows that the two legs are axially guided in two guide ways  103 ,  104  diametrically opposed and made in the external wall of the female base  4 . 
         [0054]    Legs  101 ,  102  have respectively one free extremity  101 A,  102 A, the free extremity of leg  101  is protruding relative to the female base  4 , while the free extremity  102 A of leg  102  is flush with female base  4  at the upper surface  4 D of the female base  4 . As shown in  FIG. 11 , legs  101 ,  102  are blocked in this position by two detents  105 ,  106  respectively formed in the respective guide ways  103 ,  104  of the female base  4 , cooperating with two notches  107 ,  108  in the form of slots respectively made in legs  101 ,  102 , blocking the displacement of sleeve  6  in axial direction A in position P 1 . 
         [0055]      FIG. 10  shows the connector  100  according to the invention with the male end-piece  3  fully inserted in coupling  2 , and the locking sleeve  6  occupying the second axial position P 2 . In this second axial position of locking sleeve  6 , the free extremity  101 A of leg  101  is now flush with the female base  4  and the extremity  102 A of leg  102  of sleeve  6  is axially retracted relative to the female base  4 . As shown in  FIG. 12 , legs  101 ,  102  are blocked in this position by detents  105 ,  106  which now cooperate respectively, on the one side, with a notch  109  in the form of a slot made in leg  101  above notch  108 , and on the other side, with the free extremity  102 A of leg  102 , blocking the displacement of the sleeve in axial direction A in position P 2 . 
         [0056]    As described previously in correspondence with connector  1 , the displacement of the locking sleeve  6  from position P 1  to position P 2  and inversely, requires the application of a certain axial force on leg  101 . The difference in height between extremities  101 A,  102 A of legs  101 ,  102  of sleeve  6  provides advantageously a flat contact area on the upper surface  4 D of the female base  4 , serving for the installation of coupling  200  on the male end-piece  3 . 
         [0057]    The respective dimensions of detent  105  and notches  108 ,  109  (same as the respective dimensions of detent  106 , notch  107  and extremity  102 A) are adjusted to correspond to the axial travel of the sleeve between the two position P 1  and P 2  which is approximately equivalent to the thickness in axial direction of staple  5 . 
         [0058]    While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
A crawling ( 2) for a connector ( 1) for fluid pipes comprises a female base ( 4) in which a male end-piece ( 3) is inserted in a certain axial direction (A) to produce a sealed connection, an elastically deformable C-shaped metal wire spring ( 5) for immobilizing the end-piece in the base, and a locking sleeve ( 6) which can move axially around the spring and the base so as to occupy a first axial position (P 1) in which the spring can deform radially towards the outside of the base, and a second axial position (P 2) prohibiting the radial deformation of the spring. The sleeve has at least one radial interior recess ( 12 A, 12 B) into which the spring retracts when it is deformed by the end-piece and when the sleeve occupies said first position. Each recess is offset axially with respect to the spring when the sleeve occupies said second position, preventing the radial deformation of the spring and thereby safeguarding the scaled connection.