Patent Publication Number: US-2005115615-A1

Title: Connector having an embedded valve

Description:
TECHNICAL FIELD  
      The present invention relates to a connector having a valve embedded therein for use in evaporation piping of fluid through the connector, for example, in the fuel supply system of an automobile.  
     BACKGROUND TECHNOLOGY  
      It is desirable that the vapor generated in the fuel tank of an automobile be contained such that it will not be discharged to the atmosphere. A popular vapor discharge prevention mechanism that provides such a treatment is the type in which the generated vapor is adsorbed in a canister. The vapor discharge prevention mechanism of this type requires evaporation piping for connecting a fuel tank with a canister or breather circuit, or for connecting a fuel tank with inlet piping, for which a reduction in the amount of vapor generated during the fuel supply is essential and the canister size must be reduced. A one-way valve or a check valve is used to serve the above purposes by maintaining the appropriate pressure inside the fuel tank.  
      Such a one-way valve used for evaporation piping or breather piping, for example is embedded in the connector housing of a piping connector as taught in U.S. Pat. No. 6,397,884 and Japanese Unexamined Patent Application Publication No. 2003-028010. The embedded valve comprises: a valve seat provided to the path or through-path of the connector housing; a valve body for opening or closing the valve gate and restricting the flow rate of the vapor flowing from the fuel tank to the canister or inlet-pipe side; and, a compression coil spring which pushes the valve body toward the fuel tank. As the vapor pressure increases inside the fuel tank, the valve body moves to the canister side or inlet against the spring force of the compression coil spring, thereby opening the valve gate. As the vapor pressure increases, the accumulated vapor in the fuel tank flows into the canister or inlet pipe through the embedded valve.  
      In the embedded valve configuration as described above, the amount of vapor flowing from the fuel tank side to the canister side or to the inlet pipe side is mostly dependent on how much the valve gate that is seated on the valve body opens. Hence, the spring characteristics determine not only the minimum pressure applied to the valve body to open the valve gate, but also the vapor flow rate from the fuel tank side to the canister or inlet-pipe side.  
      Nevertheless, it is likely that the characteristics of a compression coil spring, particularly a spring of low rigidity, will change over time due to fatigue or aging. As a result, the mode of controlling the vapor flow rate must be changed significantly since the conventional configuration controls the entire vapor flow solely by the spring characteristics of a compression coil spring, in other words, the characteristics of the valve are dependent on those of the spring.  
      In the vapor control method which is dependent only on the spring force of a compression coil spring, the motions of a valve body can become unstable after the valve is open: for example, any change in the vapor pressure shakes the valve body. Unstable motions of the valve body cannot stabilize the vapor flow rate. Yet, minimizing the vapor flow rate is desirable in order to suppress evaporation so as to maintain a low vapor level thereof.  
      The objective of the present invention is, therefore, to provide a connector with a long-life embedded valve that can ensure a stable flow rate.  
      The connector of the present invention comprises: a connector housing having a path for fluid flow through the connector, an embedded valve embedded in the fluid path of the connector housing, a first connector component provided upstream of the embedded valve for upstream piping and a second connector component provided downstream of the embedded valve for downstream piping; wherein the embedded valve comprises: a valve seat provided in the fluid path of the connector housing having a valve gate; a valve body which opens or closes the valve gate on the valve seat; a compression coil spring which pushes the valve body in the upstream direction, and an exit-orifice disposed downstream of the valve seat for restricting the discharge rate of fluid flow through the downstream piping. The spring characteristics of the compression coil spring are, for example, set for the purpose of ensuring a given pressure required to open the valve. In addition, the cross-sectional area to diameter ratio at the exit-orifice or the cross-sectional area to diameter ratio of the fluid path at the exit orifice is set on the assumption that, for example, a given pressure results in a given flow rate from upstream to downstream. The characteristics of a valve embedded in the connector of the present invention are dependent on the exit-orifice and the characteristics of the compression coil spring. Hence, the valve body motion can be stabilized.  
      Nonetheless, if there is a disturbance in the fluid flow coming from the upstream piping, the valve body may slide along the inner circumference of the path being shaken in a radial direction. If the valve body slides along the inner circumference of the path, noise from abrasion occurs and is transmitted to the passenger compartment of an automobile, thereby disturbing the silence thereof. For this reason, it is desirable that an inlet-end orifice is provided more toward upstream than the valve seat provided in the path of the connector housing so as to stabilize the fluid flow coming from the upstream piping.  
      The connector and embedded valve of the present invention has excellent durability because of its ability or certain valve characteristics to withstand aging. In addition, the flow rate of the connector is not controlled only by the force derived from the compression coil spring, and motions of the valve body are stabilized to produce a minimal effect on the fluid flow rate. This effectively prevents the internal fluid from evaporation and provides a good degree of freedom in designing of the connector. Further, the exit-end orifice and the compression coil spring together will determine the valve characteristics. Accordingly, the number of compression coil springs to be managed is reduced and the components to be assembled are easily obtained while reducing manufacturing costs thereof.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a connector of the present invention having an embedded valve;  
       FIG. 2  is a cross-sectional view of the connector of  FIG. 1 ;  
       FIG. 3  is an enlarged cross-sectional view of the first connector component part of the connector of  FIG. 1 ;  
       FIG. 4  is a perspective view of the valve body of the embedded check valve in  FIG. 1 ;  
       FIG. 5  is a diagram illustrating the connector of  FIG. 1  being used for evaporation piping;  
       FIG. 6  is a diagram illustrating the valve body of  FIG. 3  in the open state, and  
       FIG. 7  is a diagram illustrating the pressure-flow rate characteristics as a function of the diameter of the exit-end orifice. 
    
    
      Embodiments of the present invention are described herein with reference to the drawings.  
      Connector  1  having an embedded valve used for the evaporation piping of a gasoline fuel tank comprises for example: connector housing  3  made of polyacetal (POM); and check valve  7  embedded in path  5  of connector housing  3 . Connector housing  3  further comprises: body component  9 , having embedded check valve  7 ; first connector component  11 ; and second connector component  13  such that these three components are integrated to provide a T-shape wherein first connector component  11  with a smaller diameter is formed upstream and extends along the axis; second connector component  13  with a larger diameter is formed downstream and extends in the direction orthogonal to the axial direction.  
      As shown in  FIG. 3 , first connector component  11  is constructed with: upstream component  15  and downstream component  21 ; wherein upstream component  15  has an outer circumferential plane with a diameter gradually expanding in the downstream direction; two protruding flange components  19 ,  19  with a triangle shape in cross-section having a diameter expanding in the downstream direction are provided at a distance along the axis one after another from upstream to downstream. A resin tube for upstream piping (hereinafter referred to as first resin tube  23 ), as shown in  FIG. 5 , is tightly fitted to the outer circumference or outer circumferential plane to connect the resin tube thereto. Upstream outer circumferential plane  25  of downstream component  21  between upstream component  15  and protruding flange component  17  is formed with a small diameter or is formed as a relatively deep groove. Seal-ring or first seal-ring  27 , shown in  FIG. 5 , is placed on upstream outer circumferential plane  25  to fit the resin tube thereto.  
      The inner circumferential plane of first connector component  11  is a cylindrical inner surface throughout the length and inlet  29  or a part of path  5  is provided thereon. It also constitutes inlet orifice  31  having, for example, half of the diameter of inlet  29  at the upstream edge or tip portion.  
      Upstream body component  9  of connector housing  3  has valve housing component  33  formed integrally with cylindrical first connector component  11  having a small diameter; downstream body component  9  has outlet component  35  formed integrally with cylindrical second connector component  13  having a large diameter; valve housing  33  and outlet component  35  are integrated by tightening the upstream portion of outlet component  35  about the outer circumference of the downstream portion of valve housing component  33  during ultrasound welding. Reference Numeral  36  is such a welded portion. Outlet component  35  is constructed with cylindrical base  37  and fitting component  39  having a large diameter wherein cylindrical base  37  is a downstream short extension along the axis which is incorporated with the center length of second connector component  13 ; fitting component  39  is incorporated with the upstream portion of cylindrical base  37  such that fitting component  39  is fitted to the outer circumference of the downstream portion of valve housing component  33 . Annular spring-receiving groove  41  is provided to the annular plane of upstream cylindrical base  37 . The inner plane of cylindrical base  37  is a simple cylinder and constitutes outlet  43 . Outlet  43  and the inside second connector component  13  communicate with each other through exit-end orifice  45 . Exit-end orifice  45  is given about ¼ of the inner diameter of outlet  43  on cylindrical base  37 .  
      Upstream inner plane  47  of valve housing component  33  of connector housing  3  is a simple cylindrical plane extending with a diameter which is 1.5 times larger than that of outlet  29  of first connector component  11 , and provides guiding hole  49  which is a part of path  5  having a nearly equal diameter to that of outlet  43  of cylindrical base  37 ; downstream inner plane  47  is a simple cylindrical plane extending with a diameter which is 1.7 times longer than that of guiding hole  49 , and provides sliding hole  51  which is a part of path  5  as well. Between slide  51  and guide  49 , inner plane  47  of valve housing  33  has first taper component  53  and second taper component  55 , wherein first taper component  53  extends from one axial end of slide hole  51  toward upstream inner plane  47  in such a manner that the diameter of valve housing component  33  reduces relatively sharply in a tapered manner; second taper component  55  extends from the upstream of first tapered component  53  to the other axial end of the guiding hole in such a manner that the diameter of housing component  33  reduces relatively gradually in a tapered manner. Second tapered component  55  or the inner plane thereof functions as a valve seat, providing a valve gate inside the valve seat.  
      Valve body  57  constituting embedded check valve  7  is housed in valve housing component  33 . As depicted in detail in  FIG. 4 , valve body  57  is integrally formed with blockage component  63 , downstream guide  65 , and upstream guide  67  wherein blockage component  63  is formed integrally about the outer circumference of thin disk-like component  59  with annular component  61  slightly extending in the downstream direction; upstream guide  67  extends from the outer circumference of disk-like component  59  of blockage component  63  in the upstream direction. The material used for valve body  57  is POM.  FIG. 4  is a perspective view of valve body  57 . In blockage component  63 , connecting outer circumferential plane  69  for disk-like component  59  and annular component  61  is formed in such a manner that connecting outer circumferential plane  69  circularly expands outward in cross-section, thereby providing a contact plane which closely touches second tapered component  55  or a valve seat having a liner cross-section [(See  FIG. 6 )].  
      Downstream guide  65  is constructed with multiple, specifically six, plate-like downstream sliding legs  71  that are formed integrally with annular component  61  about the circumference thereof at an even distance, more specifically, at a 60 degree angle. Each downstream sliding leg  71  comprises: holding component  73  provided on annular component  61 ; and rectangular sliding component  75  formed integrally with the other end of holding component  73  along the axis in such a manner that the thickness direction of these plates corresponds to the tangent direction of annular component  61 . The distance from the center of annular component  61  to the outer end plane along the radius of each sliding component  75  is equal to or somewhat smaller than the radius of the inner circumferential plane of sliding hole  51 ; the outer end plane along the radius of each sliding component  75  is formed as a plane extending along the axis of sliding component  75  such that the downstream connector  13  can slide along the inner circumferential plane of sliding hole  51 . Holding grooves  77  extending or having slits pointing in the upstream direction are formed to be at nearly identical positions along the radius of annular component  61 .  
      Upstream sliding guide  67  is constructed with multiple, specifically four, plate-like sliding legs  79  formed integrally with the outer circumference of disk-like component  59  at even intervals, specifically at 90 degree angles, about the circumference thereof. Upstream sliding legs  79  are arranged to form right angles with the thickness direction of the plates, which corresponds to the tangential direction of disk-like component  59 , and with the radial-outer end of the plates extending along the axis. The distance between the central part of disk-like component  59  and the outer end or outer end plane along the radius of upstream sliding leg  79  is approximately equal to or slightly smaller than the radius of the inner circumferential plane of guiding hole  49 . The outer end plane along the radius of upstream sliding leg  79  is formed such that it can slide along the inner circumferential plane of guiding hole  49 .  
      The upstream portion of valve body  57  of the above configuration is housed in holding groove  77  formed on sliding component  75  of downstream sliding leg  71 . It is also pushed by compression coil spring  81  in the upstream direction to cause upstream guide  67  to enter guiding hole  49  of body component  9  and to cause connecting outer circumferential plane  69  of blockage component  63  to touch approximately the mid point along the axis of second tapered component  55  or the valve seat, wherein the downstream portion of compression coil spring  81  is housed in spring receiving groove  41  on cylindrical base  37 .  
      As is apparent from  FIG. 2 , second connector component  13  has connector components  83 ,  83  of the same configuration at the first and second end along the length direction or the direction perpendicular to the axis. Each connector component  83  comprises: length-wise outer side component  85  and length-wise center side component  91  wherein outer side component  85  has an outer circumferential plane whose diameter increases toward the center along the length thereof; center side component  91  has protruding flange component  87  in a rectangular shape in cross-section and two protruding flange components  89 ,  89  in a triangular shape in cross-section; all of  87 ,  89 , and  89  are formed about the outer circumferential plane, which is a simple cylindrical outer plane extending at the center side of length-wise outer side component  85 ; the diameter of the outer circumferential plane thereof increases towards the center along the length; and two protruding flange components  89 ,  89  are formed one after another from the outside to the center side at a distance along the length. The resin tubes of the downstream piping consists of second resin tube  93  and third resin tube  95  (See  FIG. 5 ) and these are tightly fitted to the outer circumference or outer circumferential plane to provide a connection thereof. Length-wise outer circumferential plane  97  on center side component  91  between outer side component  85  along the length and protruding flange component  87  is formed as a relatively deep annular groove. Accordingly, the sealing rings or second sealing ring  99  and third sealing ring  105  (See  FIG. 5 ) are arranged along the length to fit the resin tube thereto. Note that Reference Numeral  103  is a hook component.  
       FIG. 5  is a diagram illustrating connector  1  with an embedded valve used for evaporation piping.  
      The evaporation piping is configured as follows: first resin tube  23 , which extends from a gasoline fuel tank, is fitted to the outer circumference of first connector component  11  of connector  1  with an embedded valve. Second resin tube  93  (downstream piping) for use in upstream piping, which is different from first resin tube  23 , is fitted to connector elements  83  of second connector component  13 ; and third resin tube  95  (downstream piping) for use in downstream piping, which is not the piping in which first resin tube  23  and second resin tube  93  are used, is fitted to other connector elements  83  of second connector component  13 . In the figure, Reference Numerals  105 ,  107 , and  109  are flanges that regulate the amount of the resin tube to be fitted or pressed therein.  
      Now, if the vapor pressure increases in a gasoline fuel tank which is the case illustrated in  FIG. 6 , valve body  57  moves in the downstream direction against a spring force generated by compression coil spring  81  to cause the valve body  57  to open ( FIG. 6  is a diagram illustrating valve body  57  in the open state). As the valve moves in the downstream direction and connecting outer circumferential plane  69  of blockage component  63  leaves the midpoint of second tapered component  55  along the axis, vapor flows into sliding hole  51  (arrow A) through the annular space with a large diameter between connecting outer circumferential plane  69  and the axial midpoint of second tapered component  55 . The incoming vapor, then, flows out from outlet  43  and enters second connector  13  (arrow B) through exit-end orifice  45 . Then, valve body  57  can move in the downstream direction until sliding component  75  of second end sliding leg  71  touches the annular upstream end plane of cylindrical base  37 . The motion of valve body  57  along the axis causes guiding hole  49  of upstream sliding leg  79  and sliding hole  51  of downstream sliding leg  71  on the inner circumferential planes thereof to slide together. As a result, valve body  57  will not tilt during the movement. If the vapor flow is disturbed, valve body  57  is pressed against inner circumferential plane  47  of body component  9  in a biased manner, possibly generating a fricative sound. Nevertheless, the presence of the inlet-end orifice at the edge of the upstream of first connector component  11  along the axis can stabilize the vapor flow. Note that upstream sliding leg  79  will not be pushed away from guiding hole  49  because upstream sliding leg  79  is of a length longer than the distance between downstream sliding leg  71  and upstream cylindrical base  37  as is shown in  FIG. 3  or the movable distance that valve body  57  travels along the longitudinal axis (from the valve open to valve closed position) provided that the valve body  57  is blocked.  
       FIG. 7  is a chart illustrating the pressure-flow rate (PQ) characteristic as a function of diameter or cross-sectional area of exit-end orifice  45 .  
      Measurements were taken for the pressure-flow rate or valve properties for connector  1  with an embedded valve, where the inner diameter of outlet  43  was set to 8.0 mm; the spring properties of compression coil spring  81  were set such that valve-opening pressure of valve body  57  remains at 1.4 kPa; the diameter of exit-end orifice  45  was changed from 1.8 mm to 2.0 mm, 2.2 mm, and 2.4 mm; the pressure was measured in kPa at first connector component  11  side and the flow rate was measured in L/min or l/m for the fluid passing through exit-end orifice  45 . In the figure, the results of measurements are plotted in accordance with the following orifice diameters: 1.8 mm for Curve  1 ; 2.0 mm for Curve  2 ; 2.2 mm for Curve  3 ; 2.4 mm for Curve  4 ; 2.4 mm for Curve  5  wherein in Curve  5 , the spring constant of compression coil spring  81  was increased 5 times while maintaining the valve-opening pressure constant at 1.4 kPa. As is apparent from  FIG. 7 , the PQ properties change little even though the spring constant of the compression coil spring is increased 5 times. However, any change in orifice diameter significantly changes the PQ properties. This means that even though aging change the spring properties to some extent, such a change will not be significant.  
      If the connector and embedded valve of the present invention is installed in the evaporation piping in an automobile, for example, the vapor generated in the fuel tank can be handled appropriately.