Abstract:
A capless filler neck creates a vapor-tight closure for a fuel system using a spring-loaded door and a latch structure that anchors the door to create a vapor-tight seal. The filler neck includes a spring that biases the door shut and a wedge arrangement that acts as the latching structure. The wedge arrangement includes a movable plate that selectively engages with the door to pull the door shut with sufficient force to form and maintain the vapor-tight seal.

Description:
TECHNICAL FIELD 
   The present invention relates to filler tube closures, and more particularly to a vapor-tight closure for a fuel tank. 
   BACKGROUND OF THE INVENTION 
   Vehicle emissions standards have become increasingly stringent due to the increased knowledge of the negative environmental effects of hydrocarbon emissions, which are generated by fuel vapors into the atmosphere. For vehicles and other fuel-operated devices, controlling and containing fuel vapors is of great importance in reducing emissions. Most vehicles contain an on-board diagnostics system that monitors whether the fuel system is completely vapor-tight. Although it is relatively easy to contain vapors when they are already in the fuel system, the greatest amount of vapor tends to be generated by the refueling process rather than vehicle operation. Past studies have shown that more hydrocarbon emissions were generated during the refueling process than when the entire tank of fuel is actually burned. 
   More particularly, the refueling process requires a user to remove a closure, such as a gas cap, which seals a filler tube in the fuel system when the gas cap is attached to the filler tube. Although the gas cap is normally designed to be vapor-tight when it is attached to the filler tube, it is common for users to replace the gas cap too loosely, creating a leak. Although some fuel systems have a spring-loaded flapper that shuts the nozzle opening, this flapper simply closes the opening without sealing it. The leak in the fuel system caused by the loose gas cap is detectable by the on-board diagnostics system in the vehicle, which usually indicates the leak by illuminating a “check engine” light. However, because the “check engine” light itself does not specifically indicate that the leak is the problem, diagnosing the leak at the gas cap is time-consuming and inconvenient, particularly in view of how commonly loose caps occur due to user error. 
   There is a desire for a filler tube closure that can create a vapor-tight seal in a reliable fashion. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a capless filler neck that creates a vapor-tight closure for a fuel system without relying on a user to properly attach a gas cap to create a seal. The capless filler neck includes a spring-biased flapper at the filler neck opening and a latch assembly that anchors the flapper to create a vapor-tight seal. The filler neck includes a spring that biases the flapper shut and a wedge arrangement that engages with the flapper to hold the flapper shut with sufficient force to form the vapor-tight seal. 
   In one embodiment, the wedge arrangement includes a movable plate configured to release the flapper in a released position and to engage with the flapper in a latched position. Either the plate or the flapper may have a groove with a ramp for engagement. Because the flapper and the plate are wedged together when the flapper is engaged with the plate, the flapper is pulled securely to compress a seal disposed on the flapper. Moreover, the engagement between the flapper and the plate ensures that the flapper is held securely with a relatively high amount of force to maintain the vapor-tight seal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of a latch assembly according to one embodiment of the invention in a released position; 
       FIGS. 2A and 2B  are section views of  FIG. 1  taken along lines A—A and lines B—B, respectively; 
       FIG. 3  is a plan view of the latch assembly of  FIG. 1  in a latched position; 
       FIGS. 4A and 4B  are section views of  FIG. 3  taken along lines A—A and B—B; respectively; 
       FIG. 5  is an exploded view of the latch assembly of  FIG. 1  with an optional protective cover. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIG. 5  illustrates components in a capless filler neck system  100  having a latch assembly  101  that secures and seals a flapper  102  in a filler neck opening  104 . The filler neck opening  104  is formed in a support  106  that supports the latch assembly  101 . The flapper  102  itself may be in the form of any movable door that closes the filler neck opening  104 . In one embodiment, the flapper  102  has a seal  107  formed around its periphery to create a vapor-tight closure when the flapper  102  is latched by the latch assembly  101  against the support  106 . The flapper  102  is movable between an open position and a closed position. 
   The latch assembly  101  itself includes a movable plate  110  that slides or otherwise moves on top of the support  106 , preferably in a linear fashion, between a released position and a latched position. Note that although the illustrated embodiment shows a sliding plate  110 , the plate  110  can move in any fashion to latch the latch assembly  101  without departing from the scope of the invention. The movable plate  110  in the illustrated embodiment has a keyhole-shaped opening  112  having a release portion  114  and a latch portion  116 . As shown in the Figures, the release portion  114  is large enough to allow the flapper  102  to move freely without touching the movable plate  110  when the movable plate  110  is in the released position. The latch portion  116  is configured so that it is smaller than the flapper  102  in at least one dimension so that the flapper  102  and the area of the movable plate  110  surrounding the latch portion  116  engage with each other when the movable plate  110  is in the latched position. In an alternative embodiment, the plate  110  may have a generally U-shaped configuration having only the latch portion  116 . This reduces the overall length of the plate  110  by omitting the release portion  114 . 
   In one embodiment, the flapper  102  has slots  124  formed on opposing portions of its circumferential edge, and the movable plate  110  has engagement portions, such as ramp portions  126 , formed on areas corresponding to the slots  124 . However, the reverse configuration may also be used (i.e., with the slots  124  on the movable plate  110  and the ramp portions  126  on the flapper  102 ) without departing from the scope of the invention. The actual dimensions of the ramp portions  126  may include, for example, a subtle change in the thickness of the movable plate  110  to create a wedging action between the slots  124  and the ramp portions  126  when the movable plate  110  and the flapper  102  engage with each other completely. This wedging action holds the flapper  102  securely in place with a high amount of force. 
   The travel path of the movable plate  110  may be restricted by a guide structure  120 , such as guide channels  122 , grooves, ridges, or other similar structures. Note that although  FIG. 5  shows the guide structure  120  as a separate component that also acts as an impact and as a locator for the resilient member  130 , in the latch assembly  101 , the guide channels  122  or other guide structures may be integrated into the support  106  itself, as well. One or more resilient members  130  are attached to the movable plate  110  to bias the movable plate  110  toward the latched position. This ensures that the flapper  102  is latched automatically when the movable plate  110  is in its default position (i.e., the latched position). 
   Referring to  FIGS. 1 ,  2 A, and  2 B, moving the movable plate  110  in the direction of arrow X against the biasing force of the resilient member  130  (e.g., during a refueling process) pulls the movable plate  110  so that the flapper  102  is disposed in the release portion  114  of the opening  112  in the movable plate  110 . This action disengages the movable plate  110  from the flapper  102 , allowing the flapper  102  to be moved easily to the open position by, for example, a fuel nozzle. 
   Referring to  FIGS. 3 ,  4 A, and  4 B, when the fuel nozzle is removed from the filler neck opening  104 , the biasing force of the resilient member  130  causes the movable plate  110  to move toward the latched position. This causes the ramp portions  126  on the movable plate  110  to engage with the slots  124  on the flapper  102 , pulling the flapper  102  slightly closer toward the support  106 . The pulling action compresses the seal  107  against the underside of the support  106  to form a vapor-tight seal. 
   By incorporating a latching structure having a latching plate that engages with the flapper in a wedged fashion only when the door is closed, the invention ensures that the amount of force needed to open the door is minimized while at the same time ensuring that the forces holding the flapper closed are high enough to maintain a vapor-tight seal and to prevent the flapper from inadvertently opening, even when a force is applied to the flapper  102 . The wedged latching structure provides these functions without requiring complicated rotating mechanisms or multiple latches to hold the flapper  102  in place and eliminate a chamber outside of the flapper  102  and seal  107  where trapped liquid may reside. 
   The inventive latch structure may be used in conjunction with a protective cover  200  having a sliding door  202 , such as the cover described in commonly-assigned U.S. application Ser. No. 11/047,071.  FIG. 5  illustrates capless filler neck system  100  with the cover  200 . The door  202  on the cover is coupled to the movable plate  110  so that the door  202  and the plate  110  can be moved simultaneously simply by moving the door  202  alone. The cover  200  protects the latch assembly  101  and flapper  102  from being damaged by environmental contaminants. In the illustrated embodiment, a retainer  204 , such as a bolt or a pin, on the door  202  engages with an engagement structure, such as a protrusion  206 , on the movable plate  110  when the door  202  is moved toward the open position. Note that any engagement structure is possible without departing from the scope of the invention; for example; the door  202  may be configured to have a protrusion for engaging with the movable plate  110 . 
   The engagement between the retainer  204  on the door  202  and the protrusion  206  causes the movable plate  110  to move to the released position when the door  202  is moved to the open position. Moreover, when the biasing force applied to the movable plate  110  by the resilient member  130  moves the movable plate  110  back toward the latched position, the engagement between the retainer  204  and the protrusion  206  causes the door  202  to move automatically toward the closed position through the same biasing force. 
   Linking the movement of the door  202  with the movement of the movable plate  110  allows the door  202  and the movable plate  110  to be moved in a single motion. During the refueling process, the user can simply press the tip of the fuel nozzle against the door  202  to open the door and unlatch the flapper  102  at the same time, freeing the flapper  102  so that the nozzle can be inserted into the filler neck opening  104 . The nozzle holds the door  202  open and holds the in the unlatched position during refueling. Removal of the nozzle from the filler neck opening  104  frees the door  202  and the movable plate  110 , causing the biasing force applied to the movable plate  110  by the resilient member  130  to push the movable plate  110  back to the latched position to pull the flapper  102  against the support  106  and seal the filler neck opening  104 . At the same time, the biasing force also pulls the door  202  back to the closed position due to the engagement between the door  202  and the movable plate  110 . As a result, incorporating the cover  200  allows the flapper  102  to be protected from harsh environmental conditions automatically when the nozzle is removed from the filler neck opening  104 . 
   The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.