Vapor control in a fuel dispensing nozzle
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of my copending U.S. Patent Application Ser. No. 553,529, filed Feb. 27, 1975, for Vapor Control. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to the improvements in the vapor handling capacities of fuel dispensing nozzles. 
     A number of systems have been proposed for dealing with the hydrocarbon vapors displaced from the vehicle&#39;s fuel tank during a refueling operation. One such system is disclosed and claimed in the above-mentioned U.S. Patent Application Ser. No. 553,529. Each such system requires that the fuel dispensing nozzle be equipped to capture the displaced vapors and to convey them to a vapor conduit interconnecting the nozzle and any vapor handling system. 
     My previous patent application U.S. Ser. No. 553,529 teaches various valving arrangements for achieving better control of flow through the vapor recovery conduits. It is a principle object of the present invention to provide yet further improved valving arrangements for control of such flow. It is an additional object to provide an improved arrangement for sealing the vehicle fuel tank mouth during refueling in order to prevent the escape of hydrocarbon vapors to the atmosphere, as well as to prevent the introduction of air into the vapor recovery conduits. It is a further object of the present invention to provide the improved arrangements just mentioned in a form which can be easily incorporated into existing fuel dispensing nozzles. 
     SUMMARY OF THE INVENTION 
     Briefly, the invention features improvements in a fuel dispensing nozzle comprising a body having a fuel conduit leading to a spout insertable into a fuel tank and having a manually operable fuel valve, a vapor conduit for transporting vapor displaced from the tank to a remote vapor handling system, and a vapor shut-off valve in said vapor conduit. In the improved nozzle, the vapor shut-off valve comprises a diaphragm having surfaces facing the vapor conduit and a chamber within the nozzle, respectively. The diaphragm causes the vapor conduit to be blocked in a first position and not to be blocked in a second position. Biasing means urge the diaphragm toward its position that blocks the conduit. The nozzle further includes valve opening means for urging the diaphragm toward its second position only when fuel is flowing past the nozzle&#39;s fuel valve. 
     Preferably, a vapor regulator valve is also provided in the nozzle for regulating vapor flow through the vapor conduit in response to predetermined vapor conditions within the fuel tank and the conduits. The vapor pressure regulator valve may comprise a second diaphragm supported intermediate the first diaphragm and the vapor conduit with a resilient spacer disc between the two diaphragms for transmitting force therebetween. A spring biases the second diaphragm away from the vapor conduit (i.e., toward a &#34;valve open&#34; configuration). Excessive vacuum conditions on the conduit side of the second diaphragm will draw that diaphragm toward the conduit thereby sealing the conduit (i.e., &#34;valve closed&#34; configuration) overcoming the force of the biasing spring. The operation of the regulator valve is overridden by the shut-off valve which, under the influence of its biasing spring presses through the resilient spacer disc and forces the second diaphragm into a valve closed orientation whenever there is no fuel being dispensed from the nozzle. 
     In another aspect, the invention features improvements in a shroud member which surrounds a portion of the nozzle spout and which defines a portion of the vapor recovery conduit system. One improved feature of such a shroud is the provision of a magnetic disc as a portion of the shroud end plate, thereby assuring intimate contact of the end plate with the magnetically susceptible material which forms the mouth of the fuel tank. The shroud may further include a substantially inextensible, force-transmitting element extending between the end plate and the body of the fuel dispensing nozzle, whereby the magnetic attraction between the end plate and the fuel tank mouth may help support the weight of the nozzle to prevent accidental displacement of the nozzle from the fuel tank. Another desirable feature of such a shroud is the provision of one or more pressur relief valves integrally formed with the material of the shroud in order to relieve pressure differentials between the interior and exterior of the shroud. 
     As to each of the features of the invention summarized above, of course, the improved structural relationships according to the present invention can be provided in the form of replacement parts for existing fuel dispensing nozzles, as well as being incorporated into newly manufactured nozzles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features, and advantages of the invention will appear from the following description of a particular preferred embodiment, which is illustrated in the accompanying drawings. In the drawings: 
     FIG. 1 is a partially sectioned side elevation of a fuel dispensing nozzle incorporating features of the present invention; and 
     FIG. 2 is a view taken at 2--2 of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF A PARTICULAR PREFERRED EMBODIMENT 
     Referring to the drawings, the dispensing nozzle includes a body 10, a spout assembly 12, and a spout shroud 14. Body 10 comprises casting 16 having a fuel conduit 18 extending from a supply hose 20 to the spout. A biased-closed fuel valve 22 is operated by conventional manual fuel valve operator 24. A shut-off mechanism 26, which can be of the type disclosed in U.S. Ser. No. 553,529, is also provided and includes passageway 28 connecting chamber 30 above diaphragm 32 with the outlet end 34 of spout 36, and a second passageway 38 leading to the gasoline conduit 18 just below valve 22. 
     The spout assembly 12 includes spout 36, and a fitting 40 which secures the spout to the body casting 16. The shroud 14 includes a flexible bellows 42 surrounding the upper portion of the spout, an attachment portion 44 secured to the fitting 40, and an end plate 46 which includes an opening 48 communicating with the space between the bellows and the spout. End plate 46, which seals against the mouth of fuel tank fill pipe 50 when the spout is inserted into the fill pipe, also includes a disc magnet 52 (preferably, a ceramic-rare earth magnet having eight poles per face). The nozzle can be held in place in the fill pipe by a ring 54 which catches under the lip of the fill pipe mouth. (Alternatively, a conventional spring wrapped around the lower spout segment could be used.) 
     A series of relatively inextensible filaments 55 can be provided extending between the end plate and the attachment portion. When under tension, the filaments would serve to support part of the nozzle&#39;s weight by the magnetic attraction to the fill pipe. Naturally, a variety of other structures could perform the same function. 
     The shroud 14 also includes a resilient receptacle 56 which is integral with a shroud portion 58 adjacent the attachment portion 44 and which has an opening 60 for receiving a tube 62 in a leak-proof friction fit. In the preferred embodiment illustrated, the shroud 14 is molded as an integral unit from a resilient flexible material that is substantially unaffected by hydrocarbon liquid or vapors. One suitable material is urethane rubber. The shroud portions 44 and 58, as well as the receptacle 56 and the end plate 46, preferably have a greater wall thickness than the bellows portion 42. The thicker portions, of course, have functions which require somewhat greater rigidity, and somewhat less flexibility, than the bellows. It is also preferred that the magnet 52 be completely encased in the material of which the shroud is formed in order to protect the magnet from damage and to eliminate the possibility of sparks which could develop if the magnet were to directly strike the fuel tank fill pipe 50. As will be evident to those skilled in the art, a shroud formed in this fashion is easily installed on existing conventional fuel dispensing nozzles. 
     The space between the shroud 14 and the spout 36 forms a conduit for receiving vapors displaced from the fuel tank. Such vapors enter that space through the opening 48 and exit through a tube 62 which extends from the receptacle 56 through an opening in a cap assembly 64 of the nozzle to convey the vapors to a chamber 66 in the cap assembly. The chamber 66, in turn, communicates with a passageway 68, also provided in the cap assembly. The passageway 68 leads to an external conduit 70 that is connected to a remote vapor handling system (e.g., the jet pump-powered suction system described in the above-mentioned U.S. Application Ser. No. 553,529). Preferably, the tube 62, passageway 68, and conduit 70 have the same inner diameter (e.g., 5/16 inch) in order to provide a relatively uniform vapor flow conduit. 
     The cap assembly 64 comprises a stacked arrangement of parts which can be secured to the conventional nozzle body 16 by a series of screws (not shown) passing through all parts of the stack. The main structural elements of the cap assembly 64 are a body 72, spacer 74, and cap 76. The body 72 includes an opening 78 which receives the tube 62 and which communicates with the chamber 66 provided in the body 72. The passageway 68 in the body 72 terminates in an upwardly facing annular surface 80 which, as described below, forms a valve seat. The lower portion of body 72 is relieved to define the chamber 30 that cooperates with diaphragm 32 to provide the full-tank shut-off feature described in detail in the above-mentioned U.S. Patent Application Ser. No. 553,529. 
     A vapor pressure regulator diaphragm 82 and a vapor shut-off diaphragm 84 are clamped around their peripheries between, respectively, the body 72 and spacer 74 and the spacer 74 and cap 76. In the rest configuration illustrated, the diaphragms 82, 84 are substantially parallel and are separated by a spacer disc 86, preferably formed from a closed cell foam rubber and having a thickness substantially equal to the thickness of spacer 74. A small opening 88 in the spacer 74 maintains the volume between the diaphragms 82 and 84 and atmospheric pressure. The cap 76 defines a chamber 90 above the shut-off diaphragm 84. A shut-off diaphragm biasing spring 92 is disposed in that chamber and biases the diaphragm 84 toward the diaphragm 82 and the valve seat 80. The regulator diaphragm 82 is biased upwardly by a spring 94 disposed around the valve seat 80 in the chamber 66. The biasing forces of springs 92 and 94 are chosen such that the force of spring 92 can overcome the force of spring 94. Aligned openings 96 and 98 in the spacer 74 and the cap 76 connect the chamber 90 with the conduit 38. 
     Referring to FIG. 2, the shroud portion 58 is provided with a pair of integral pressure relief valves 100, 102. Each valve comprises a pair of adjacent flexible flaps 104, each integral with a biasing panel 106 that is, in turn, integral with the wall 58 at an opening 108 therein. As will be evident to those skilled in the art, valve 100 will permit air to enter the shroud to relieve an excessive vacuum and value 102 will permit vapor to escape from the shroud to relieve excessive pressure. With tight seal of end plate 46 to the fill pipe 50, the valves serve as an additional protection against pressure extremes which could damage the vehicle fuel tank. 
     The dual function valving arrangement provided in the cap assembly 64 can best be described by considering the operation of the regulator diaphragm 82 absent the shut-off diaphragm 84, and then considering the constraints imposed by the presence of the shut-off diaphragm 84. The vapor pressure regulator diaphragm is biased away from the valve seat 80 (i.e., in a &#34;valve open&#34; configuration) by the spring 94. In this &#34;normal&#34; orientation of the diaphragm 82, hydrocarbon vapor is free to pass through the chamber 66, passageway 68, and conduit 70 to the remote vapor handling system (not shown). Excessive vacuum levels beneath the diaphragm 82, however, can overcome the biasing force of spring 94 and cause the regulator valve to close (i.e., the diaphragm 82 to engage the valve seat 80). 
     It is very desirable, however, that the vapor recovery passages be sealed at all times when fuel is not being dispensed by the nozzle. This is accomplished, according to the present invention, by the vapor shut-off diaphragm 84. As is illustrated in FIG. 1, absent the flow of fuel through the nozzle, the spring 92 overcomes the force of spring 94 and its force is transmitted through diaphragm 84 and spacer disc 86 to force the diaphragm 82 against the valve seat 80. Thus, even if a suction is applied to the remote end of vapor conduit 70 (e.g., a system such as described in the above-mentioned U.S. Patent Application Ser. No. 553,529 in which a suction is generated when the fuel pump is turned on, even if the fuel is not yet being dispensed through the nozzle) air is prevented from being sucked into the vapor return system. When fuel is being dispensed, however, a slight vacuum is created in the chamber 90 above the shut-off diaphragm 84 by the venturi effect as fuel flows past the mouth of conduit 38. The suction is transmitted through conduits 38, 96, and 98 to the chamber 90. Spring 92 is chosen to have the force such that the vacuum level produced in chamber 90 (e.g., about 2 to 3 inches of water), when acting upon the exposed surface of diaphragm 84, is sufficient to overcome the force of spring 92, thereby causing a compression of spring 92 and a movement of the diaphragm 84 away from the diaphragm 82. When this occurs, of course, the regulator diaphragm 82 is free to act independently of the shut-off diaphragm 84 and to perform its regulatory function. An interruption in the flow of fuel causes the return of diaphragm 84 and spring 92 to the configuration shown in FIG. 1, so that the operation of diaphragm 82 is overridden by the shut-off diaphragm 84. 
     As will be evident to those skilled in the art, the vapor shut-off valving arrangement shown in FIG. 1 can be provided in a system where no vapor pressure regulator valve is required. In the so-called &#34;vapor balance&#34; systems for example, there is no suction applied to the vapor return conduit 70 and no possiblity of damage to the vehicle&#39;s fuel tank by excessive vacuum levels. The regulator valve is thus superfluous. It would still be desirable, however, to positively seal the vapor return conduit system when the nozzle is not in use in order to prevent air from entering that system. The vapor shut-off valve arrangement shown in FIG. 1 would provide a simple and effective way of achieving this, with the diaphragm 84 engaging the valve seat 80 directly. 
     The cap assembly 64 which provides the vapor conduit valving arrangements according to the present invention, can be provided as a replacement assembly for the conventional caps which enclose the full tank shut-off mechanism in existing fuel dispensing nozzles. Naturally, there may be modification of the cap assembly parts as illustrated in FIG. 1 in order to accommodate slightly different structural features of existing nozzles and/or different vapor handling systems (e.g., with a &#34;vapor balance&#34; system the diaphragm 82, spring 94, spacer 74, and spacer disc 86 could be eliminate). Similarly, the shroud 14 can be provided as an &#34;add-on&#34; feature for existing nozzles. 
     While particular preferred embodiments of the present invention have been illustrated in the accompanying drawings and described in detail herein, other embodiments are within the scope of the invention and the following claims.