Abstract:
A snap-fitted arrangement of a valve on a pump includes means of which at least one is elastic such that one of the means is integrated with the valve and the other means is integrated with the pump. The means are arranged in a complementary manner in a linear engagement of the male-female type such that the elastic means elastically deforms during engagement. One of the means includes a channel and the other means includes a protuberance which engages the channel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage application under 35 USC 371 of PCT Application No. PCT/EP2014/064828 having an international filing date of Jul. 10, 2014, which is designated in the United States and which claimed the benefit of French Patent Application No. 1357558 filed on Jul. 31, 2013, the entire disclosures each are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to the snap-fitted arrangement of a valve on a pump body or at the end of a common rail supplying injectors. 
       TECHNOLOGICAL BACKGROUND TO THE INVENTION 
       [0003]    A valve is generally arranged and attached on a high-pressure pump body by means of screws. The valve is first centered on the body by fitting a female cylindrical surface of the valve onto a male cylindrical surface of the pump body, then securing the assembly by means of screws. Furthermore, the arrangement of a high-pressure valve at the end of the common rail of an injection system also comprises a centering means then an attachment. In this case the valve body may be threaded so as to be directly screwed onto the end of the rail, which is itself threaded. 
         [0004]    Whatever the type of valve and the device on which it is placed, the arrangement requires attachment means, specific machining and assembly time. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention aims to solve these problems by proposing an arrangement of a valve on a device, the casing of the valve being snap-fitted onto the body of the device. 
         [0006]    More particularly, the casing and the body have, integrated therein, means of which at least one is elastic, said means being arranged in a complementary manner in a linear engagement along a main axis. The engagement is of the male-female type and is a force fit. During the engagement, the elastic means deforms. 
         [0007]    One of the means comprises a channel and the other means comprises a protuberance arranged so as to engage in the channel at the end of the force-fitting such that the valve casing is snap-fitted onto the body of the device. 
         [0008]    The casing and the body are provided with radial faces arranged pressing against one another when the protuberance engages in the channel such that the casing is snap-fitted onto the body and is axially positioned relative to the body. 
         [0009]    During the engagement of the protuberance in the channel, the elastic means returns to its rest shape retaining a residual elastic deformation such that the casing is snap-fitted, positioned axially A and held radially relative to the body. 
         [0010]    The channel and the protuberance are provided with complementary faces held against one another by the residual elastic deformation. This produces an axial force pressing the casing against the body such that the valve is snap-fitted, axially and held radially relative to the device. 
         [0011]    The complementary means comprise two cylindrical, tubular portions of which at least one is crenellated such that the merlons are elastically deformable. 
         [0012]    The protuberance is an annular bead integrated into the internal face of the female tubular portion and in which the channel is an annular channel integrated into the external face of the male tubular portion. 
         [0013]    The complementary faces of the channel and of the bead are conical faces whose vertices are on the main axis and are oriented towards the interior of the body. 
         [0014]    Furthermore, once assembled, the valve and the device may be separated in a non-destructive manner. The elastic portion deforms as before. 
         [0015]    More particularly, the body is that of a high-pressure fuel pump and the valve, arranged by snap-fitting on the pump body, controls the ingress of fuel into the pump. 
         [0016]    The invention also relates to a valve able to be arranged in an arrangement created according to the preceding paragraphs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Other features, aims and advantages of the invention will emerge upon reading the following detailed description, and with reference to the appended drawings, which are provided by way of non-limiting example and in which: 
           [0018]      FIG. 1  is an axial section through a valve casing arranged on a high-pressure pump. 
           [0019]      FIG. 2  is a detail of  FIG. 1 . 
           [0020]      FIG. 3  is an external view of the valve casing of  FIG. 1 . 
           [0021]      FIG. 4  is an axial section through a valve arranged at the end of the common rail of a system on a high-pressure pump. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    A first non-limiting embodiment of the arrangement  10  according to the invention is now described with reference to  FIGS. 1, 2 and 3 . 
         [0023]    A valve  12 , of which only the casing  14  is shown, is arranged at the head of a high-pressure pump  16 . 
         [0024]    The body  18  of the pump  16  is provided with an open bore extending along a main axis A and surrounded at its opening by a cylindrical projection  20  having a first diameter D 1  (called out in  FIG. 4 ). At the base of the projection  20 , there is created an annular channel  22  and, on the periphery of the projection  20 , the body  18  is provided with a radial disk surface  24  connecting to the projection  20  along a peripheral fillet  26  forming the bottom of the channel  22 . The bottom of the channel has a second diameter D 2  (called out in  FIG. 4 ). The fillet  26  connects upwards, in the conventional and non-limiting sense of the figures, with a widening conical surface  28  whose vertex S 1  is on the main axis A inside the pump body  16 . The conical surface  28  returns, at the top, to the first diameter D 1  of the main cylindrical surface  30  of the projection  20 . In one preferred embodiment, the angle at the vertex of the cone is between 10° and 45°. 
         [0025]    The casing  14  of the valve  12  is provided with a generally cylindrical peripheral base  32  which, in the arrangement  10 , is coaxial A with the projection  20 . The base  32  has a cylindrical internal surface  34  having a third diameter D 3  (called out in  FIG. 4 ), barely larger than the first diameter D 1 , and which terminates at its lower end, in the conventional and non-limiting sense of the figures, in a peripheral internal bead  36  forming a radial protuberance. The bead  36  connects to the cylindrical surface  34  along a short conical surface  38 , whose vertex S 2  is on the main axis A close to the vertex S 1  of the conical surface  28  of the projection  20 , the angle at the vertex of the conical surface  38  being slightly less than the angle at the vertex of the cone of the channel  22 . The conical surface  38  of the casing  14  extends towards the end of the base  32  as far as a fourth diameter D 4  (called out in  FIG. 4 ), slightly larger than that, D 2 , of the bottom of the channel  22 , then it widens rapidly, connecting downwards to a radial disk surface  40 . 
         [0026]    Furthermore, and more particularly visible in  FIG. 3 , the base  32  of the casing  14  is crenellated such that the merlons  42  thus created are provided with a slight radial elasticity. The peripheral bead  36 , for its part, is only on the merlons  42 . 
         [0027]    The arrangement  10  of the valve  12  on the pump body  18  is now described. 
         [0028]    Before the assembly is effected, the valve  12  and the pump  18  are aligned along the main axis A and brought together such that the bead  36  is in contact with the vertex of the projection  20 . By exerting, on the casing  14  of the valve, an axial force oriented towards the pump, the merlons  42  open slightly in an elastic manner such that the projection  20  enters into the base  32  of the valve, the vertex of the bead  36 , of diameter D 4 , engaging around the cylindrical surface  30  and sliding until the bead  36  is arranged in the channel  22 . The elastically deformed merlons  42  return to a shape close to the rest shape but retain a residual elastic deformation. The two conical surfaces  28 ,  38 , are then pressed against one another by the residual deformation, which produces, on each merlon  42 , a force F normal to the conical surfaces  28 ,  38  in contact, the resulting force of all the forces F being along the main axis A and oriented towards the pump  16 . The casing  14  of the valve, on which this resulting axial force acts, is then pressed against the pump body, the two disk surfaces  24 ,  40  being in contact against one another. 
         [0029]    The leaktightness of the arrangement  10  is ensured by an O-ring  44  arranged between the casing  14  and the pump body  18 , the seal  44  having been placed prior to the engagement of the valve base  32  about the projection  20 . 
         [0030]    It therefore appears that the arrangement  10  thus created positions the valve  12  relative to the body  18  both in the direction of the main axis A, the valve  12  being forced to press against the pump body  18 , and in the radial direction, the tight fit of the diameters preventing this type of movement. 
         [0031]    The residual deformation of the merlons  42  holds in position but the forces produced may be overcome and the valve  12  may be repositioned angularly by turning it about the main axis A. 
         [0032]    Similarly, the valve  12  may be removed by exerting, on the casing  14 , an “upward” axial force such that the merlons  42  again open elastically and once more slide along the projection  20 . 
         [0033]    Many alternatives may be created according to the above-described teachings. Thus, the projection may be crenellated such that the merlons thus formed deform radially towards the main axis. In addition, the engagement with the female valve and the male pump may be reversed, the valve base entering the body, the merlons opening whether they are on the valve or on the projection. 
         [0034]    A second embodiment is now described briefly with reference to  FIG. 4 . It relates to a valve  12  arranged at the end of the common rail  16  of an injection system. The principle is similar to that of the first embodiment, the crenellated base of the valve being provided with a bead which is received in a groove created at the base of a cylindrical portion extending from the common rail. The main difference resides in the position of the O-ring seal which in this case is arranged at the bottom of the channel and on which the end of the bead presses. 
         [0035]    As shown in the figures, the casing  14  encloses an electromagnetic actuator comprising a fixed winding and an axially mobile core cooperating with a valve. In this context, the casing  14  of the valve  12  is made of magnetic steel and the described snap-fitted arrangement provides excellent direct contact between the steel of the casing  14  and that of the pump body or that of the common rail, providing magnetic continuity favorable to the operation of the whole.