Abstract:
A float operated vapor vent/rollover valve for a fuel tank has a converging section formed in the liquid inlet to the valve which, in response to surges or waves in the fuel, creates a liquid jet impinging on the bottom of the float causing rapid closing of the valve and preventing liquid fuel from entering the vapor vent lines to the vapor storage device.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to vapor vent valves of the type employed with a motor vehicle fuel tank for controlling vapor flow during refueling and vapor emissions during vehicle operation. In particular, the invention relates to fuel tank vapor vent valves of the type employing a float for controlling vapor venting from the tank during refueling and preventing liquid spillage into the vapor emission control system in event of vehicle rollover.  
         [0002]     In normal vehicle operation the fuel is subjected to a complex surface wave pattern due to vehicle motion and these rapidly moving waves have created problems as they contact the float operated vent valve. Upon such a wave contacting the float operated valve, the inertia of the float may prevent the float from rising or responding rapidly enough to close the valve and prevent liquid fuel from escaping into the conduits connected externally to the vapor vent valve. Under severe vehicle motion, such rapidly formed waves in the fuel can cause liquid to enter the vapor lines and in certain circumstances the vapor storage device, such as a charcoal canister, connected to the vapor vent lines. The presence of liquid fuel in the vapor vent lines or the canister can result in malfunction of the vapor emission control system.  
         [0003]     Therefore, it has been desired to provide a way or means of alleviating the effects of rapid wave patterns in the fuel in a tank on a float-operated rollover/vent valve and to prevent passage of liquid fuel through the valve. It has further been desired to provide such protection from rapidly formed waves in the liquid fuel in the tank in a manner that does not require complete redesign of the fuel vapor vent valves currently employed and thus eliminate the need for costly retooling for manufacturing such valves.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     The present invention provides a float operated rollover and vapor vent valve for a vehicle fuel tank which employs a converging section in the liquid fuel inlet of the valve such that rapidly moving waves in the liquid fuel in the tank create a jet which impinges on the undersurface of the float thereby increasing the response of the float to the wave in the tank and preventing liquid fuel from escaping through the valve. The converging section in the inlet may be formed by modifying only portions of an existing valve and thereby eliminates the need of costly retooling of the entire valve. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a cross-section of a first embodiment of a fuel vapor vent/rollover valve employing the present invention; and,  
         [0006]      FIG. 2  is a view similar to  FIG. 1  of an alternative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0007]     Referring to  FIG. 1 , the present invention is embodied in a valve assembly indicated generally at  10  having a valve body  12  formed of material impervious to the fuel as, for example, polyamide material partially filled with glass particles. The valve body includes a hollow float chamber  14 , a vapor vent passage  16  formed in a fitting  18  which is intended to extend exteriorly of a fuel tank, portions of the wall of which are indicated by reference numeral  20 . A valve body  12  has the lower portion thereof forming the valving chamber  14  extending downwardly through an access opening  22  formed in the upper wall of the fuel tank. The body  12  has an outwardly extending flange  24  which, along with fitting  18 , the upper portion  26  of the body is overmolded with material compatible with weldment to the tank material as denoted by reference numeral  28  as, for example, high density polyethylene material (HDPE).  
         [0008]     An insert  30  is disposed in the valving chamber  14  and is secured therein by any suitable expedient, as for example, by weldment and has formed thereon an annular valve seat  32  with a vent passage  34  formed therein which communicates through upper portion  26  with the passage  16  in hose fitting  18 .  
         [0009]     A float assembly indicated generally at  38  is received in the valving chamber  14  and is moveable therein in response to fuel level in the tank. The float assembly includes a float  39  with resilient flexible valve member  40  disposed on the upper end of the float which closes valve seat  32  upon the float rising in response to the fuel level in the tank reaching a predetermined level. Valve member  40  is retained with the float by a cage  41 . The float assembly  38  is retained in the valving chamber by a cup-shaped member  42  which is attached over the lower portion  12  of the valve body; and, the member  42  has an inlet passage  44  formed in the lower or closed end thereof which has a converging section  46  formed on the upstream end of passage  44 . The float is biased in an upward direction by a calibration spring  46  having one end registered against the closed end of the member  42  and the opposite end registered against the lower end of the float assembly  38 .  
         [0010]     The converging section  46  of the inlet passage  44  functions to increase the velocity of the liquid fuel impinging on the inlet  46  due to sudden wave action in the fuel thereby producing a jet of fuel which impinges on the lower end of the float assembly  38  and raises the float rapidly to close valve member  40  against the valve seat  32 .  
         [0011]     It will be understood that the overmold material  28  over the periphery of the flange  24  extends axially downwardly over the periphery of flange  24  to provide an attachment surface  47  which may then be attached to the fuel tank as, for example, by weldment, such as by spin welding or sonic welding.  
         [0012]     Referring to  FIG. 2 , an alternate embodiment invention is shown in the valve assembly indicated generally at  50  which has the valve body  52  truncated adjacent the outwardly extending flange  54  which is overmolded by material  56  and which is secured to the wall  58  of a fuel tank by suitable weldment in a manner similar to that of the embodiment of  FIG. 1 .  
         [0013]     Valve body  52  has an insert  60  disposed therein with a vapor vent passage  62  formed therethrough and having a valve seat  64  formed on the lower end thereof. Vent passage  62  communicates through upper portion  53  of the valve body with a vent outlet passage  66  formed in a hose fitting  68  in a configuration similar to that of the embodiment of  FIG. 1 .  
         [0014]     A cup-shaped member  70  has the upper rim thereof attached to the undersurface of flange  54  by any suitable expedient; however, in the presently preferred practice of the invention the cup-shaped member  70  is attached thereto by weldment. The cup-shaped member  70  forms a float chamber  72  into which is slidably received and guided for movement therein a float assembly indicated generally at  74  which includes a flexible valve member  76  retained on the upper end of the float assembly. It will be understood that upon rising fuel level in the tank float assembly  74  moves upwardly causing the valve member  76  to close against valve seat  64  and preventing vapor or liquid fuel entering the vent passage  62 .  
         [0015]     The lower or closed end of the cup-shaped member  70  retains the float assembly  74  in the chamber  72 . A spring  78  has one end thereof registered against the inside of the closed end of the cup-shaped member  70  with the opposite or upper end registered against the lower end of the float assembly  74  thereby biasing the float in an upward direction for calibration of the valve  76  for closing at the proper desired liquid level of fuel in the tank.  
         [0016]     The lower end of the cup-shaped member  70  has a liquid fuel inlet passage  78  formed therein which has on the upstream or inlet end thereof a converging section  80  which functions to increase the velocity of the fuel entering passage  78  upon experiencing a sudden wave in the fuel. The increased velocity of the fuel passing through passage  78  creates a jet which impinges on the undersurface of float assembly  74  and causes the assembly  74  to rise rapidly closing valve  76  against valve seat  64 .  
         [0017]     The present invention thus provides a simple and low cost way of modifying a vapor vent valve to provide a fluid jet at the inlet in response to wave surges in the liquid fuel so as to impinge on the undersurface of the float valve to cause rapid closing thereof and thereby prevent liquid fuel from entering the vapor emission conduits and vapor storage canister.  
         [0018]     Although the invention has hereinabove been described with respect to the illustrated embodiments, it will be understood that the invention is capable of modification and variation and is limited only by the following claims.