Abstract:
A refueling valve for a motor vehicle includes a body connected to the upper wall of a fuel tank in vertical depending relationship thereon and the body has a body top or cover with a vapor exit passage adapted to be connected to a fuel vapor storage canister, a baffle is connected to the valve body intermediate the ends thereof to form a fuel space and a vapor space; the body includes a portion depending from the cover that has a vapor exit port communicating with the vapor space and wherein the vent exit port has a valve seat closed by a valve mounted on one end of a connecting rod that has its opposite end connected to a float within the fuel space and wherein the vapor exit port remains open until the fuel tank is filled and/or fuel slosh in the tank raises the float to close the valve; the connecting rod is directed through a port in the baffle to provide for vapor exhaust across the baffle during tank fill and to restrict fuel bypass into the vapor space during fuel slosh within the tank. In one embodiment a baffle is a transverse wall and in another embodiment the baffle is an inverted cone having a center vapor relief port therein and a peripheral wall formed with fuel return openings.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to refueling valves and more particularly to refueling valves with fuel vapor vents and liquid traps for use with a motor vehicle fuel tank.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the typical fuel vapor vent valve for a motor vehicle fuel tank wherein the valve is adapted to prevent spillage in case of shaking, tilting or rollover of the vehicle, the valve normally opens the fuel tank to an orifice that is connected by a vapor exit passage in the valve body to a vapor hose leading to a fuel vapor storage device. The valve body is commonly made as a one-piece plastic injected molded part that for simplicity of design has a simple direct connection between the orifice and the vapor exit passage. However, this connection has a tendency to collect and pass any liquid fuel issuing from the orifice under pressure from the tank on to the vapor storage canister. The latter contains a fuel vapor absorber such as carbon and any liquid fuel delivered thereto will quickly reduce its vapor adsorbing ability. It is difficult to configure the top of the molded body with a vapor exit passage connection that would somehow trap this liquid after it passes through the orifice and then drain the trapped liquid back to the tank. This is also the case where the valve is omitted and only venting is provided through an orifice in a vent body that mounts on the fuel tank.  
           [0003]    As to any such possible fuel drainage back to the tank in the case of a vent assembly having a valve that is adapted to block the orifice on overfill, vehicle shaking, tilting and/or vehicle rollover, there is also the consideration of adversely affecting the operation of the valve as it is required to provide for normal venting operation in an upright position but close under these various circumstances to block exit of fuel from the tank. Any such drainage path for liquid fuel trapped downstream of the orifice can not provide a possible path for fuel vapor to vent around the valve in the normal upright attitude of the tank or allow liquid fuel to escape from the tank when tipped or inverted. An example of such systems is set-forth in U.S. Pat. No. 5,044,389, assigned to the assignee of the present invention.  
           [0004]    One solution to such problems is set-forth in U.S. Pat. No. 5,413,137, also assigned to the assignee of the present invention. The fuel vapor vent assembly set-forth in the &#39;137 patent embodies a fuel impervious insert that is adapted to be mounted in such a vent or vent valve body and defines both a vertically oriented vent orifice and a liquid basin extending about the exit of this orifice. A simple cavity formed in the interior of the top of the plastic body co-operates with the basin in the insert to define an expansive chamber elevated above the orifice and this chamber communicates the orifice with a horizontal vapor exit passage in the plastic body adapted to be connected to a vapor storage device. The expansive chamber forms an elevated liquid trap at the exit of the orifice that traps liquid from the venting fuel vapor while permitting venting to continue therethrough and then drains the trapped liquid in the basin back into the tank through the orifice in the insert when the pressure in the fuel tank is relieved. The liquid trapping chamber has a ceiling directly opposite the orifice dead ending the vapor stream issuing therefrom and the vapor exit passage is connected to the expansive chamber at a point above the basin. These features combine to aid in separating any liquid fuel out from the vapor and down into the basin and prevent it from passing on to the vapor exit passage and thence to the vapor storage canister.  
           [0005]    While suitable for their intended purpose, the fuel vapor vent assemblies set-forth in the aforesaid prior art patents do not include provision for venting vapor from the tank as the float is closing at the same rate at which the fuel tank is being filled nor do they provide a predetermined vapor dome space within said tank to accommodate vapor pressure increases when the refueling valve is closed. Further, the unitary body arrangement is configured to locate the valve seat close to the tank top and vent openings are located at the base of the unitary body such that they will be immersed in fuel when the tank level reaches the float so that venting will be restricted as the float moves between its normally open position and its normally closed position.  
           [0006]    Another fuel vapor vent valve that obviates the aforesaid problem is set-forth in U.S. Pat. No. 5,687,756 also assigned to the assignee of the present invention. The valve shown in the &#39;756 patent provides a fuel vapor vent device that will vent vapor during fuel fill at the same rate as the rate of fuel flow into the tank while preventing liquid fuel flow to a fuel vapor storage canister. Such operation is in part provided by a valve body having a vapor exit passage and a liquid inlet passage and the body is connected to the top of a fuel tank in depending relationship therewith and the valve includes a float and a valving element carried by the float and tiltable with respect to the float for compensating for tilt and further characterized by the body further including a vapor exit port adjacent the top and also including a vent tube with a valve seat located below the vapor exit port for preventing liquid fuel particles from entering the vapor exit passage. The vent tube has a length more than one half of that of said body for locating said valve seat at a distance from the upper wall of the fuel tank that will provide for a predetermined vapor dome space within said tank to accommodate vapor pressure increases when the refueling valve is closed. While suitable for its intended purpose, the length of the vent tube is not always suitable for application in different fuel tank configurations and requires assembly and the valve seat thereon is not isolated from fuel to so as to minimize fuel carryover to a charcoal canister resulting from violent dynamics of fuel in a closed vessel in response to vehicle maneuvers.  
           [0007]    Accordingly, an object of the present invention is to provide a fuel vapor control valve configured to be connected vertically within the upper space of a fuel tank and including connections to a charcoal canister and further including a valve body having a float therein with a valve having a sealing surface isolated from fuel and engaging and sealing against a valve seat for preventing fuel flow through a vapor vent port from the valve body and the valve body having an opening configured to direct fuel vapors from the fuel tank to the interior of the valve body the fuel vapor control valve being characterized by a baffle connected to the interior of the valve body separating the valve body into a vapor space and a fuel space and a connecting rod connected to the float and raised therefrom a predetermined distance to isolate a valve element sealing surface from fuel and directed generally vertically through the baffle and a valve element located on the connecting rod within the vapor space and wherein the baffle and connecting rod are configured such that fuel entry into the vapor space will be delayed until the float is displaced by the entry of fuel in the valve body to cause the valve element to seal the valve seat to prevent fuel passage through the vapor vent port during violent vehicle maneuvers.  
           [0008]    A further object is to provide such a fuel vapor control valve of wherein the baffle divides the valve body to form an upper chamber and a lower chamber; the fuel inlet openings into the valve body communicating only with said lower chamber and vapor exit openings being formed within the valve body to communicate the vapor dome of a fuel tank with the upper chamber and wherein a skirt on the valve body cover is configured for encompassing the valve seat and the valve element when it is both opened and closed; the valve body having fuel vapor openings therein located outboard of the skirt at a position shielded by the skirt such that the skirt deflects fuel droplets directed through the fuel vapor openings from entering the vapor vent port.  
           [0009]    Still another object of the invention is to provide such a fuel vapor control valve having a body dividing baffle therein including a hole for guiding the valve sealing surface isolating connecting rod within the body and for permitting movement of the connecting rod with respect to the baffle.  
           [0010]    One feature of the invention is to provide the baffle in the aforesaid vapor control valve as an inverted cone baffle connected to the valve body and including a hole for passage of the valve sealing surface isolating connecting rod there through during closure of the vent valve and the inverted cone baffle operative to deflect fuel particles in the lower chamber from passing through the vapor vent port when said vent valve is open.  
           [0011]    Another feature of the invention is to provide the baffle formed as a planar divider wall connected to and directed transversly across the valve body and including a hole for guiding the connecting rod there through during closure of the vent valve and the planar divider wall operatively deflecting fuel in the lower chamber of a valve body from passing through the vapor vent port.  
           [0012]    Yet another object of the invention is to provide universal connections between the valve sealing surface isolating connecting rod, the float and the valve element for adjusting the position of the valve element during closure against the valve seat in response to fuel slosh produced by any normal to violent vehicle maneuvers.  
           [0013]    A further object is to provide such connections as a first ball joint on the upper end of the float connected to a socket on one end of the connecting rod and the connecting rod including a second ball joint connected to a ball socket on a valve carrier and including a valve element on the valve carrier located by the upper and lower connections to seal a valve seat for preventing vapor escape when the float is raised within the valve body by displacement of liquid flowing into the valve body through the inlets therein.  
           [0014]    These and other objects, advantages and features of the present invention will become more apparent from the following description and accompanying drawings wherein: 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a sectional view of a motor vehicle fuel tank vapor control valve associated with a fragmentary section of a fuel tank and the valve including a baffle arrangement and valve assembly constructed in accordance with the present invention; and  
         [0016]    [0016]FIG. 2 is a sectional view of a vapor control valve assembly like that shown in FIG. 1 of another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    Referring to FIG. 1, there is illustrated a fuel vapor control valve device  10  for venting a motor vehicle fuel tank  12  to a fuel vapor storage canister  14  containing a fuel absorber such as carbon. The fuel tank  12  is made of high density polyethylene (HDPE).  
         [0018]    The valve device  10  comprises body  16  that includes a generally cylindrical upper end  16   a  that is fit on a cylindrical extension  19  received in an opening  20  in the top of the fuel tank  12 . The valve device  10  further comprises a closed upper end cover or top  22  having a radially outwardly extending annular flange  24  that abuts with the tank about the opening  20 .  
         [0019]    The top  22  is also made of a high density polyethylene (HDPE), this material being selected for its ability to weld to the fuel tank  12  and is merely illustrative with it being understood that other suitable plastic or metallic materials can be used. Thus the flange  24  is welded about its perimeter to the tank to sealingly secure the fuel vapor vent valve device in place in a normal vertically oriented or upright position as shown. The valve body top  22  has an integrally formed hose fitting or outlet tube  26  by which the fuel vapor vent valve device is adapted to be connected by a hose  28  to the vapor storage canister  14 .  
         [0020]    Mounted in the valve body is a fuel isolated valve assembly including a valve carrier  30 , raised connecting rod  32 , float  34 , valve  36  and a closure member  38  at the bottom end  16   b  of the valve body  16 . A liquid inlet opening  39  is provided in the closure member  38  for communicating the interior of the valve body with the liquid fuel as the tank fills for purposes to be discussed. Also, four vertical slots  41  are annularly located in the valve body  16  around the float  34 .  
         [0021]    The valve carrier  30  has an annular skirt  30   a  and an elongated ball socket  40 . A ball  42  is provided on the upper end of the raised connecting rod  32  for universally connecting the upper end of the connecting rod  32  to the valve  36 . Likewise the lower end of the raised connecting rod  32  has an elongated ball socket  44  that is connected to a ball  45  formed on the upper surface of the float  34  for universally connecting the lower end of the connecting rod  32  to the float  34 .  
         [0022]    The float  34  is located within the valve body  16  and has a outer wall  34   a  centered in spaced relationship to the inner wall  16   c  of the valve body  16 .  
         [0023]    The valve carrier  30  has an integral valve element  36  formed as a central upstanding valve element with a slightly raised curved elastomeric outer surface  36   a  aligned with a valve seat  48  formed on the inner surface of the cover  22  at the entrance of a vent tube  50  formed within the cover  22  and defining a vapor exit passage  52 . The vent tube  50  receives fuel vapors from the fuel tank from vapor exit ports  54  formed in the upper end  16   a  of the valve body  16  at a point located closely adjacent the upper wall or inner surface  12   a  of the fuel tank and at a point that is covered by a vapor flow baffle  56  that covers the valve seat  48  to prevent fuel carry over into the vapor exit passage and hence into the fuel vapor canister  14 .  
         [0024]    In this embodiment, the float  34  includes an integral end closure disk  58  that will maintain the outer wall  34   a  of the float  34  in spaced relationship to the inner surface  16   c  of the valve body  16 .  
         [0025]    The underside of the closure disk  58  is configured to have a conical surface or ramp  60  that is supported on a ball  62  that is, in turn, supported by the conical inner surface or ramp  64  on the closure member  38 .  
         [0026]    In the illustrated arrangement, the float and closure disk  58  are heavy enough not to flow shut at low pressure buildups in the final tank  12 , but are light enough to float in the fuel during a fuel filling operation in which the fuel level is raised in the fuel tank  12  toward the top  12   a  thereof. The weight of the closure disk  58  is placed such that the float  34  always floats straight up within the valve device  10  thereby to reduce frictional contact between the float  34  and the valve body  16 . The angle of ramp of the conical surface  64  is configured such that it will allow the ball  62  to move and shut the valve when the vehicle tilts greater than a predetermined amount, such as in a range of 30°. The ball  62  also has to be heavy enough to close the valve shut when the vehicle rolls over.  
         [0027]    In the embodiment of the invention shown in FIG. 1, the bottom closure member  38  includes tabs  38   a  thereon that are configured to fit into openings  16   d  on the bottom end  16   c  of the valve body  16 . It includes a liquid inlet opening  39  therein to allow for a substantially unrestricted flow of fuel into the interior of the valve valve body  18  for causing the float  34  to float in response to liquid fuel flow into the tank  12 .  
         [0028]    In accordance with certain principles of the present invention, the vapor exit passage  52  is configured to be large enough to vent vapors at a rate equal to or greater than the rate of fuel flow into the fuel tank during a filling operation. The communication between the vapor exit ports  54  and the inlet end of the vent tube  50  is selected so that there is no orifice-like restriction there between that can produce over pressurization of the tank during filling. The result is that there is substantially no pressure build up in the fuel tank during the refueling operation due to entrapment of vapor therein. The vapor exit ports  54  are configured and located so that vapor can vent from the tank and out the port or vapor exit passage  52  through an offset flow path defined by the fact that the vent exit ports  54  are located above and laterally of the entrance to the vent tube  50  at the valve seat  48  thereon. The vent exit ports  54  need to be large enough to cause vapors to flow without restriction during the refueling operation. Furthermore, they must be high enough in the tank so that the liquid droplets that might occur in the tank are not able to directly flow from the vapor exit ports  54  to the valve seat  48  during the refueling operation or during tilting or other jousting of the fuel tank  12  thereby to avoid any fuel carryover to the charcoal canister  14  that can affect its vapor absorbing capacity.  
         [0029]    In the embodiment of FIG. 2, the curved conical configuration of the outer surface  36   a  of the valve element  36  is selected to restrict vapor flow during closure of the float valve that would otherwise build up pressure in the fuel tank as the fuel moves the float  34  upwardly during a fuel filling operation. The curved shape of the surface  36   a  is configured so that there is enough pressure build up in the fuel tank  12  to shut the fuel nozzle supplying the fuel tank  12  from the fuel filler pipe even though the float valve is not completely closed. This allows for some of the vapor to vent and drain the fuel in the filler pipe head as the tank reaches its fuel shut off level. Additionally, the curved surface is shifted into a centered relationship with the valve seat center  46  for sealing there across when the roll-over valve is closed by the universal connections defined by the ball joint connections  40 ,  42  and  46  between the connecting rod  32 , the valve carrier  30  and the float  34 .  
         [0030]    Additionally, the above-described arrangement avoids a sudden build up of pressure in the tank that might otherwise cause a fuel spit back effect at the fill head.  
         [0031]    The position of the float, relative to the cover, determines a vapor dome height. The valve seat is positioned as far away from the fuel as possible to prevent liquid fuel from going into the port to the canister.  
         [0032]    In this embodiment, another feature is that the valve sealing action is isolated from fuel in the fuel space by the provision of a valve isolating connecting rod  32  that is extended such that the valve sealing surface  36   a  of the valve element  36  is raised well above the fuel within the bottom of the valve body  16 . This isolation is further enhanced by the provision of a baffle  66  formed as an inverted cone having its outer periphery  68  connected to the inner wall  16   c  of the valve body  16  and having a tubular extension  70  formed at is apex. The baffle  66  divides the interior of the valve body  16  into a lower chamber  72  that is a fuel chamber when the tank is filled with fuel and an upper chamber  74  that is normally separated from the fuel in the tank and that serves as a path for escape of vapor during refueling operations and when the valve element  36  is open. The baffle  66  thus creates a division between the upper and lower chambers  72 .  74 . Slots  76  are provided in the periphery  68  for vapor flow between the upper and lower chamber  72 ,  74  and to provide a path for return of any fuel that might enter the upper chamber  74  during dynamic fuel events such as sloshing in a sealed tank during vehicle maneuvers. While shown as an inverted cone, the cone  66  can be formed as a conical shape in which the extension is at the lower end of a cone that diverges upwardly from the cone rather than diverging downwardly from an extension as shown in FIG. 2.  
         [0033]    The tubular extension  70  forms a guide hole  77  for the valve isolating connecting rod  32  to provide for free relative movement with respect to the baffle  66  during valve closing and opening movements of the float  34 . The guide hole  77  aligns the connecting rod  32  generally vertically within the valve body  16  and also serves as a path for some venting of fuel vapor during certain phases of valve operation.  
         [0034]    The connecting rod  70  in addition to isolating the valve element  36  from the lower chamber  72 , serves to transfer the mechanical motion of the float  34  to the valve element  36  while maintaining a predetermined separation distance there between for isolating the valve seat  48  from the lower chamber  72  and hence for isolating the valve sealing function from fuel sloshing movements that will raise and lower the fuel level within the valve body  16  through the liquid or fuel opening  39  through the bottom closure member  38 .  
         [0035]    In addition to the space isolation provided by the length of the connecting rod and the provision of the baffle, the top cover  22  includes a depending skirt portion defined by the vapor flow baffle  56 . As shown in FIG. 2, the skirt  56  encompasses the valve seat  48  and the valve element  36  and the curved outer surface  36  thereon to assist in the isolation of the sealing interface from liquid fuel in the lower chamber  72 .  
         [0036]    In operation, the significance of the valve device  10  becomes more apparent. During normal to violent movements of fuel in a closed tank due to vehicle maneuvers the fuel sloshing within the tank can cause the float  34  to move up and down within the valve body  16  so as to cause the valve to open and close cyclically due to such fuel slosh. With the present invention when the fuel sloshes, first it will engulf the float area at the lower chamber  72  and close the valve due to upward buoyancy of the float  34  and or the mechanical assist provided by the ball  42  and ramps  60 ,  64 . Since the valve seat  48  and the seat seal defined by the curved outer surface  36   a  of the valve element  36  are isolated from the fuel affected portion of the valve at the lower chamber  72  the delay of fuel entry from the lower chamber  72  to the upper chamber  74  is delayed and this delay is sufficient to assure that the float and or mechanical action produced during roll over or tipping to shift and hold the valve element  36  tightly sealed against the valve seat  48 . Such delay and valve action effectively seals the port or vent tube  50  before any significant fuel flow passes into the upper chamber  74 . Following such valve closure and a return of less violent vehicle maneuvers the fuel in the valve will drain to the tank (if less than full) and will return to the lower chamber  72  if the tank is full thereby causing any fuel passing into the upper chamber to drain downwardly through the baffle so that when the float is lowered to open the valve only fuel vapors will be directed into the fuel vapor storage canister  14 .  
         [0037]    Thus, the valve device  10  is operative to maintain its refueling vapor flow capability while significantly decreasing the potential for liquid fuel carryover.  
         [0038]    [0038]FIG. 3 illustrates another embodiment of the invention including a refueling valve device  80  that includes a valve body  82 .  
         [0039]    Mounted in the valve body  82  is a fuel isolated valve assembly including a valve carrier  84 , raised connecting rod  86 , float  88 , valve  90  and a closure member  92  at the bottom end  82   a  of the valve body  82 . A liquid inlet opening  94  is provided in the closure member  38  for communicating the interior of the valve body with the liquid fuel as the tank fills as discussed in the aforesaid description of the embodiment of FIGS. 1 and 2.  
         [0040]    The upper end of the raised connecting rod  86  is connected to the valve carrier  84 . The lower end of the raised connecting rod  86  is connected to the float  88 .  
         [0041]    The float  88  is located within the valve body  82  and has an outer wall  88   a  centered in spaced relationship to the inner wall  82   b  of the valve body  82 .  
         [0042]    The valve carrier  84  locates the valve element  90  as a central upstanding valve element with a slightly raised curved outer surface  90   a  aligned with a valve seat  96  formed on the inner surface of a valve cover  98  corresponding functionally to the cover  22  at the entrance of a vent tube  50  in the first embodiment of FIG. 1. In this embodiment the valve seat  96  surrounds a vent port  100  that is encompassed by a skirt  102  corresponding to the skirt  56  in FIG. 2. The vent port  100  receives fuel vapors from the fuel tank from vapor exit ports  103  formed in the upper end  82   c  of the valve body  82  at a point located closely adjacent the upper wall of a fuel tank.  
         [0043]    In this embodiment, the float  88  includes a closure disk  104  that will maintain the outer wall  88   a  of the float  88  in spaced relationship to the inner surface  82   b  of the valve body  82 .  
         [0044]    The underside of the closure disk  104  is configured to have a conical surface or ramp  106  that is supported on a ball  108  that is, in turn, supported by the conical inner surface or ramp  110  on the closure member  92 .  
         [0045]    As in the case of the first embodiment of FIGS. 1 and 2, in this embodiment, the float and closure disk are heavy enough not to flow shut at low pressure buildups in the fuel tank, but are light enough to float in the fuel during a fuel filling operation in which the fuel level is raised in the fuel tank toward the top thereof. The weight of the closure disk is placed such that the float  88  always floats straight up within the valve device  80  thereby to reduce frictional contact between the float  88  and the valve body  82 . The angle of ramp of the conical surface  110  is configured such that it will allow the ball  108  to move and shut the valve when the vehicle tilts greater than a predetermined amount, such as in a range of 30°. The ball  108  also has to be heavy enough to close the valve shut when the vehicle rolls over.  
         [0046]    In the embodiment of the invention shown in FIG. 3, includes a plurality of elongated, circumferentially spaced openings  111  in the valve body  82  to allow for a substantially unrestricted flow of fuel into the interior of the valve body  82  for causing the float  88  to float in response to liquid fuel flow into an associated fuel tank such as tank  12  partially shown in FIG. 2.  
         [0047]    In accordance with certain principles of the present invention, the vapor vent port  100  is configured to be large enough to vent vapors at a rate equal to or greater than the rate of fuel flow into the fuel tank during a filling operation. The communication between the vapor exit ports  103  and the vent port  100  is selected so that there is no orifice-like restriction there between that can produce over pressurization of the tank during filling. The result is that there is substantially no pressure build up in the fuel tank during the refueling operation due to entrapment of vapor therein. The vapor exit ports  103  are configured and located so that vapor can vent from the tank and out the port  100  through an offset flow path defined by the fact that the vent exit ports  103  are located above and laterally of the entrance to the vent port  100  at the valve seat  96 . The vent exit ports  103  need to be large enough to cause vapors to flow without restriction during the refueling operation. Furthermore, they must be high enough in the tank so that the liquid droplets that might occur in the tank are not able to directly flow from the vapor exit ports  103  to the valve seat  96  during the refueling operation or during tilting or other jousting of the fuel tank thereby to avoid any fuel carryover to the charcoal canister such as canister  14  shown in FIG. 2 that can affect its vapor absorbing capacity.  
         [0048]    In the embodiment of FIG. 3, the curved conical configuration of the outer surface  90   a  of the valve element  90  is selected to restrict vapor flow during closure of the float valve that would otherwise build up pressure in the fuel tank as the fuel moves the float  34  upwardly during a fuel filling operation. The curved shape of the surface  90   a  is configured so that there is enough pressure build up in the fuel tank to shut the fuel nozzle supplying the fuel tank from the fuel filler pipe even though the float valve is not completely closed. This allows for some of the vapor to vent and drain the fuel in the filler pipe head as the tank reaches its fuel shut off level. Additionally, the curved surface  90   a  in this embodiment is somewhat more conical than in the first embodiment such that its shape will cause the valve element  90  to be shifted into a centered relationship with the valve seat center  96  for sealing there across when the refueling valve is closed.  
         [0049]    Additionally, the above-described arrangement avoids a sudden build up of pressure in the tank that might otherwise cause a fuel spit back effect at the fill head.  
         [0050]    The position of the float, relative to the top cover, determines a vapor dome height. The valve seat is positioned as far away from the fuel as possible to prevent liquid fuel from going into the port to the canister.  
         [0051]    In this embodiment, another feature is that the valve sealing action is isolated from fuel in the fuel space by the provision of a valve isolating connecting rod  86  that is extended such that the valve sealing surface of the valve element  90  is raised well above the fuel within the bottom of the valve body  82 . This isolation is further enhanced by the provision of a baffle  112  formed as a wall connected to the inner wall  82   b  at the upper end  82   c  of the valve body  82 . More particularly the outer periphery  112   a  of the baffle  112  is connected to the inner wall  82   b  of the valve body  82  and has a center hole  114  therein through which the connecting rod  86  is directed. The baffle  112  also includes fuel drain holes  116  therein that are located at circumferentially spaced points around the center hole  114 . As in the first embodiment, the baffle  112  divides the interior of the valve body  82  into upper vapor chamber  118  and a lower chamber  120  that is a fuel chamber when the tank is filled with fuel. The upper chamber  118  is normally separated from the fuel in the tank and that serves as a path for escape of vapor during refueling operations and when the valve element  90  is open. The baffle  112  thus creates a division between the upper and lower chambers  118 ,  120 . The center hole  114  and drain holes  116  serve to direct vapor flow between the upper and lower chamber  118 ,  120  and to provide a path for return of any fuel that might enter the upper chamber  118  during dynamic fuel events such as sloshing in a sealed tank during vehicle maneuvers as described in the operation of the first embodiment.  
         [0052]    The center hole  114  guides the valve isolating connecting rod  86  to provide for free relative movement with respect to the baffle  112  during valve closing and opening movements of the float  88 . The center hole  114  aligns the connecting rod  86  generally vertically within the valve body  82  and also serves as a path for some venting of fuel vapor during certain phases of valve operation.  
         [0053]    The connecting rod  86  in addition to isolating the valve element  90  from the lower chamber  120 , serves to transfer the mechanical motion of the float  88  to the valve element  90  while maintaining a predetermined separation distance there between for isolating the valve seat  96  from the lower chamber  120  and hence for isolating the valve sealing function from fuel sloshing movements that will raise and lower the fuel level within the valve body  82  through the liquid or fuel openings  111  therein and through the opening  94  in the bottom closure member  92 .  
         [0054]    In addition to the space isolation provided by the length of the connecting rod and the provision of the baffle, the top cover  98  includes the depending skirt portion  102  defining a vapor flow baffle. As shown in FIG. 3, the skirt  102  encompasses the valve seat  96  and the valve element  90  to assist further in the isolation of the sealing interface from liquid fuel in the lower chamber  120 .  
         [0055]    The operation of this embodiment generally corresponds to the description of operation for the embodiment of FIGS. 1 and 2. In the embodiment of FIG. 3, during normal to violent movements of fuel in a closed tank the float  88  moves up and down within the body  82  so as to cause the valve to open and close cyclically due to such fuel slosh. When the fuel sloshes, first it will engulf the float area at the lower chamber  120  and close the valve due to upward buoyancy of the float  88  and or the mechanical assist provided by the ball  108  and ramps  106 ,  110 . Since the valve seat  96  and the seat seal defined by the curved outer surface  90   a  of the valve element  90  are isolated from the fuel affected portion of the valve at the lower chamber  120  the delay of fuel entry from the lower chamber  120  to the upper chamber  118  is delayed and this delay is sufficient to assure that the float and or mechanical action produced during roll over or tipping to shift and hold the valve element  90  tightly sealed against the valve seat  96 . Such delay and valve action effectively seals the port  100  before any significant fuel flow passes into the upper chamber  118 . Following such valve closure and a return of less violent vehicle maneuvers the fuel in the valve will drain to the tank (if less than full) and will return to the lower chamber  120  if the tank is full thereby causing any fuel passing into the upper chamber to drain downwardly through the baffle so that when the float is lowered to open the valve only fuel vapors will be directed into the fuel vapor storage canister.  
         [0056]    The invention has been described in an illustrative manner with respect to two embodiments, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention in light of the above teachings may be made. For example, the invention has been illustrated as adapted to a refueling valve assembly wherein the valve is operated with a hollow float but the valve could also be operated with another type of floatation device such as a cellular foam member having sufficient buoyancy. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically shown and described.