Patent Publication Number: US-2006017282-A1

Title: Arrangement for connecting a rigid tube to a flexible tube

Description:
BACKGROUND OF THE INVENTION  
      The invention proposes an arrangement for connecting a rigid tube to a flexible tube.  
      More particularly, the invention proposes an arrangement for connecting a rigid tube to a flexible tube, of the type in which an upstream end section of the rigid tube is pushed coaxially into a complementary downstream end section of the flexible tube, and of the type which comprises a tubular sleeve which extends coaxially around the downstream end section of the flexible tube and is crimped radially onto the flexible tube to fix the rigid tube to the flexible tube by radial clamping.  
      Rigid tubes connected to flexible tubes are used particularly in automotive construction, for producing the braking circuit connecting the vehicle brakes to the master cylinder.  
      The rigid tubes are formed by bending so as to suit the various forms of the vehicle and so that the braking circuit does not impede the installation of the other components of the vehicle within the chassis.  
      The flexible tubes are used so that the braking circuit can be deformed, thus simplifying the fitting of the circuit to the vehicle, and allowing a part fixed to the body of the vehicle, such as the master cylinder for example, to be connected to a part that can move with respect to the body, such as a brake caliper mounted on a wheel of the vehicle for example.  
      Document GB-A-2 336 636 describes a braking circuit comprising two rigid tubes connected by a flexible tube, and an arrangement for connecting an upstream end section of a rigid tube to a complementary downstream end section of the flexible tube.  
      However, with this arrangement, the upstream end section of the rigid tube, the complementary downstream end section of the flexible tube and the sleeve are straight.  
      In addition, the flexible tube in this circuit is bent.  
      In order to limit the deformation of the flexible tube, it has been proposed for the rigid tube to be bent in the region of the arrangement which is situated on the rigid tube, downstream of the arrangement.  
      In addition, this bend in the rigid tube is situated a certain distance away from the arrangement, which distance is dependent in particular on the method used to produce the bend.  
      Thus, a straight section of the rigid tube and the arrangement which is also straight extend between the flexible tube and the bend, and that accordingly increases the bulk of the circuit in the region of the arrangement.  
     SUMMARY OF THE INVENTION  
      It is an object of the invention to propose an arrangement for connecting a rigid tube to a flexible tube for which the bend in the rigid tube is situated near the flexible tube.  
      To this end, the invention proposes an arrangement of the type described hereinabove, characterized in that the sleeve and the upstream end section of the rigid tube are curved at least in part and with more or less the same radius of curvature.  
      According to other features of the invention: 
          the sleeve and the upstream end section of the rigid tube are produced by bending, before they are assembled;     the upstream end section of the rigid tube comprises at least one straight portion and one curved portion which run on from one another, and the sleeve comprises a straight part situated in line with the straight portion of the upstream end section of the rigid tube which is deformed radially so as to crimp the sleeve;     the upstream end section of the rigid tube comprises two straight upstream and downstream end portions connected by the curved portion, and the sleeve comprises two straight upstream and downstream end parts, each situated in line with an associated straight portion of the upstream end section of the rigid tube;     the downstream end of the sleeve comprises an internal radial flange which is in abutment in the downstream direction against a radial bulge on the downstream end of the upstream end section of the rigid tube;     the upstream end of the upstream end section of the rigid tube has a radial bulge;     the radius of curvature is equal to twice the diameter of the sleeve; 
            the radius of curvature is equal to three times the diameter of the sleeve;     the upstream end section of the rigid tube can be pushed coaxially into the sleeve before it is pushed coaxially into the downstream end section of the flexible tube.    
               

    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Other features and advantages of the invention will become apparent from reading the detailed description which follows, for an understanding of which reference will be made to the attached figures among which:  
       FIG. 1  is a schematic perspective depiction of an arrangement according to the invention;  
       FIG. 2  is an axial section through the arrangement depicted in  FIG. 1 ;  
       FIG. 3  is a view similar to that of  FIG. 2 , in which the rigid tube and the sleeve are fitted before the flexible tube is fitted. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      In the description which follows, elements that are identical, similar or analogous will be denoted by the same reference numerals.  
      The figures depict an arrangement  10  for connecting a rigid tube  12  to a flexible tube  14 , in which an upstream end section  12   a  of the rigid tube  12  is pushed coaxially into a downstream end section  14   a  of the flexible tube  14 .  
      The arrangement  10  also comprises a tubular sleeve  16  which extends coaxially around the downstream end section  14   a  of the flexible tube  14 , and therefore coaxially around the upstream end section  12   a  of the rigid tube  12 , and which is crimped radially onto the downstream end section  14   a  of the flexible tube  14  so as to fix the rigid tube  12  to the flexible tube  14 .  
      To do this, the sleeve  16  comprises two upstream and downstream end parts  18  which are deformed radially by performing the crimping of two associated portions  20  of the downstream end section  14   a  of the flexible tube  14  onto two portions  22  of the upstream end section  12   a  of the rigid tube  12 .  
      Crimping the sleeve  16  also allows the connection to be a sealed one.  
      In accordance with the invention and as can be seen in greater detail in  FIG. 3 , the upstream end section  12   a  of the rigid tube  12  and the sleeve  16  are partially bent, which makes it possible to reduce the space required by the arrangement  10  if the braking circuit has an elbow situated in the region of the downstream end section  14   a  of the flexible tube  14 .  
      In this instance, the upstream end section  12   a  of the rigid tube  12  and the sleeve  16  are bent at right angles. However, it will be understood that the invention is not restricted to this embodiment of the arrangement and that the angle of bending may have any other magnitude.  
      As can be seen in  FIG. 3 , the upstream end section  12   a  of the rigid tube  12 , which is bent in accordance with the invention, comprises two upstream and downstream straight portions  22  which are connected by a bent portion  24 .  
      The upstream and downstream straight portions  22  each extend in the region of a respective upstream or downstream end of the upstream end section  12   a  of the rigid tube  12 .  
      The sleeve  16  according to the invention, which is itself also bent, comprises two straight parts  18  and a bent part  26  connecting the straight parts.  
      According to another aspect of the invention, the upstream end section  12   a  of the rigid tube  12  and the sleeve  16  are bent with more or less the same radius of curvature. This allows the upstream end section  12   a  of the rigid tube  12  and the sleeve  16  to be effectively coaxial.  
      The straight parts  18  of the sleeve  16  in this case are the upstream and downstream end parts of the sleeve  16 , which are deformed radially so as to crimp the sleeve  16 .  
      Thus, each straight part  18  of the sleeve  16  is situated in line with a straight portion  22  of the upstream end section  12   a  of the rigid tube  12 .  
      This makes it possible to have uniform clamping of the portions  22  of the end section between the straight parts  18  of the sleeve  16  and the straight portions  22  of the upstream end section  12   a  of the rigid tube  12 .  
      In addition, in order to improve the coaxiality of the assembly, the bent part  26  of the sleeve  16  is situated in line with the curved portion  24  of the upstream end section  12   a  of the rigid tube  12 .  
      According to another aspect of the invention that makes it possible to simplify the method of producing the arrangement  10 , the upstream end section  12   a  of the rigid tube  12  and the sleeve  1  are formed individually by bending before they are assembled.  
      This is because the bending of a tubular element, that is to say in this case the bending of the rigid tube  12  and of the sleeve  16  requires special-purpose tooling so as to avoid kinking the part that is to be bent. In consequence, simultaneous bending of the downstream end section  12   a  of the rigid section  12  and of the sleeve  16  would require the use of special-purpose tooling that is excessively expensive.  
      The radius of curvature of the upstream end section  12   a  of the rigid tube  12  and of the sleeve  16  are determined as a function of the dimensions of the straight portions  22  of the upstream end section  12   a  of the rigid tube  12 , so as to allow the entirety of the upstream end section  12   a  of the rigid tube  12  to be introduced coaxially into the sleeve  16 .  
      The radius of curvature is in particular determined as a function of the length “l” of the straight portions  22  of the upstream end section  12   a  of the rigid tube  12  and as a function of the inside diameter “d” of the sleeve  16 .  
      Thus, according to a first embodiment of the invention, the radius of curvature is twice the diameter of the sleeve  16 , and according to another embodiment of the invention, the radius of curvature is equal to three times the diameter of the sleeve  16 .  
      As can be seen in  FIG. 3 , the positioning of the sleeve  16  with respect to the upstream end section  12   a  of the rigid tube  12 , along its main axis, is achieved by means of an internal radial flange  28  of the downstream end  16   a  of the sleeve  16  which is in abutment against a radial bulge  30  of the downstream end of the upstream end section  12   a  of the rigid tube  12 .  
      In this instance, the upstream end section  12   a  of the rigid tube  12  is introduced into the sleeve  16  through a movement from the downstream to the upstream direction, with reference to  FIG. 3 . In consequence, the flange  28  is in abutment in the downstream direction against the bulge  30 .  
      Once the sleeve  16  has been mounted around the upstream end section  12   a  of the rigid tube  12 , the downstream end section  14   a  of the flexible tube  14  is pushed around the upstream end section  12   a  of the rigid tube  12 .  
      The flexibility of the flexible tube  14  allows the downstream end section  14   a  of the flexible tube  14  to adopt the same curvature as the upstream end section  12   a  of the rigid tube  12  and as the sleeve  16 .  
      The downstream end section  14   a  of the flexible tube  14  is pushed around the upstream end section  12   a  of the rigid tube  12  until its downstream end comes into abutment against the flange  28  of the sleeve  16 , at the same time immobilizing the sleeve  16  between the downstream end of the downstream end section  14   a  of the flexible tube  14  and the radial bulge  30  of the rigid tube  12 .  
      The upstream end  12   b  of the upstream end section  12   a  of the rigid tube  12  also comprises a second external radial bulge  32  which causes a local radial deformation of the downstream end section  14   a  of the flexible tube  14  so as to hold the downstream end section  14   a  of the flexible tube  14  in position with respect to the upstream end section  12   a  of the rigid tube  12 .  
      Next, in a final step of assembling the arrangement  10  according to the invention, the straight parts  18  of the sleeve  16  are crimped radially onto the downstream end section  14   a  of the flexible tube  14 , to clamp the downstream end section  14   a  of the flexible tube  14  onto the upstream end section  12   a  of the rigid tube  12 .  
      The arrangement  10  according to the invention is particularly well suited to motor vehicle braking circuits in which the fluid pressure is sometimes very high.  
      To prevent the flexible tube  14  from expanding radially under the effect of the pressure, and according to an alternative form of embodiment of the invention (not depicted), the outer cylindrical wall  14   e  of the flexible tube  14  is covered with a metal sheath, or braid, of known type, which is configured in such a way as to prevent the flexible tube  14  from deforming radially.  
      In order to prevent the sheath from sliding coaxially with respect to the flexible tube, at least the upstream straight part  18  of the sleeve  16  is crimped onto one end of the sheath.  
      The arrangement  10  according to the invention makes it possible to bend a section of the rigid tube  12  where it connects with the flexible tube, thus simplifying the design of the braking circuit.