Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to fuel vapor emission control for internal combustion engines. More particularly, the present invention relates to fuel tank fuel vapor emission control for internal combustion engines. 
     2. Description of the Related Art 
     Modern transportation vehicles which employ a liquid fuel conventionally also employ for storage of the liquid fuel a fuel tank. Similarly, since most liquid fuels are highly volatile, such a fuel tank typically contains in addition to the liquid fuel a fuel vapor. A concentration of fuel in the fuel vapor within the fuel tank is generally related to the temperature of the liquid fuel within the fuel tank, the amount of air in ullage volume, and the temperature of the fuel vapor within the fuel tank. 
     While a fuel vapor within a fuel tank does not typically impair operation of a transportation vehicle which is powered by an engine which employs a liquid fuel extracted from the fuel tank, upon refueling of the fuel tank with additional liquid fuel, in a first instance, the fuel vapor present in the fuel tank must of necessity be displaced. Similarly, in a second instance, when refueling the fuel tank with additional liquid fuel there is typically also newly generated additional fuel vapor incident to splashing of the additional liquid fuel which is introduced into the fuel tank. For environmental protection purposes and for economic reasons, it is desirable for such displaced fuel vapor and newly generated fuel vapor not to be released into the atmosphere. 
     Various apparatus, systems and methods have been disclosed within the art of fuel system design for attenuating, upon refueling of a fuel tank, release of a fuel vapor into the atmosphere. Typical in that regard are apparatus, systems and methods which employ either or both: (1) valving schemes to redirect displaced fuel vapors and newly generated fuel vapors in a fashion such as to avoid release into the environment; and (2) sealing means to attenuate, in a first instance, generation of fuel vapors. Representative examples of such apparatus, systems and methods are disclosed within U.S. Pat. No. 4,836,835, U.S. Pat. No. 4,898,395, U.S. Pat. No. 4,944,779, U.S. Pat. No. 4,977,936, U.S. Pat. No. 5,056,570, U.S. Pat. No. 5,404,906 and U.S. Pat. No. 5,462,100, all of which are incorporated herein fully by reference. 
     While any of the foregoing apparatus, systems and methods provides upon refueling of a fuel tank with a liquid fuel an attenuated displaced fuel vapor release into the atmosphere and/or an attenuated newly generated fuel vapor release into the atmosphere, such desirable result is often achieved only with particularly complicated piping and valving schemes, or with an otherwise incomplete attenuation of fuel vapor release into the atmosphere. 
     There thus exists within the art of fuel system design a continuing need for comparatively simple apparatus, systems and methods for more completely attenuating upon refueling of a fuel tank release of a fuel vapor into the atmosphere. 
     It is towards that object that the present invention is directed. 
     SUMMARY OF THE INVENTION 
     In order to realize the object towards which the present invention is directed, the present invention provides, in a first instance, a fuel tank filler pipe neck assembly comprising: (1) a chamber having formed therein a liquid fuel dispensing nozzle entry port and a liquid fuel exit port; (2) a liquid fuel dispensing nozzle seat disposed within the chamber, where the liquid fuel dispensing nozzle seat is sized to accept and seal a rim of a liquid fuel dispensing nozzle introduced into the liquid fuel dispensing nozzle entry port while allowing flow of a liquid fuel dispensed from the liquid fuel dispensing nozzle through the liquid fuel dispensing nozzle seat; and (3) a means for resiliently and flexibly biasing the liquid fuel dispensing nozzle seat against the rim of the liquid fuel dispensing nozzle while resiliently and flexibly sealing the liquid fuel dispensing nozzle seat to the liquid fuel exit port. 
     By: (1) employing within the present invention the chamber having disposed therein the liquid fuel dispensing nozzle seat and the means for resiliently and flexibly biasing the liquid fuel dispensing nozzle seat against a rim of a liquid fuel dispensing nozzle introduced into the chamber; and (2) when properly seating the rim of the liquid fuel dispensing nozzle upon the liquid fuel dispensing nozzle seat in the process of introducing liquid fuel into a fuel tank to which is connected the fuel tank filler pipe neck assembly of the present invention, there is avoided within the context of the present invention entrainment into the liquid fuel which is introduced into the fuel tank air which would otherwise provide for formation of fuel vapor within the fuel tank. 
     Similarly, since within the present invention the seating of a rim of a liquid fuel dispensing nozzle against the liquid fuel dispensing nozzle seat in part seals a flow of a liquid fuel from the liquid fuel dispensing nozzle with respect to a liquid fuel exit port within the fuel tank filler pipe neck assembly of the present invention, and since the present invention thus eliminates a splashing of the liquid fuel in the vicinity of a vacuum sensing port incorporated into the liquid fuel dispensing nozzle, the preferred embodiments of the present invention also provide an alternative means for shutting down the liquid fuel dispensing nozzle by means of inducing vacuum with respect to the vacuum sensing port of the liquid fuel dispensing nozzle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects, features and advantages of the present invention are understood within the context of the Description of the Preferred Embodiments, as set forth below. The Description of the Preferred Embodiments is understood within the context of the accompanying drawings, which form a material part of this disclosure, wherein: 
     FIG.  1  and FIG. 2 show a pair of schematic diagrams illustrating operation of a fuel tank filler pipe neck assembly within a fuel system in accord with a first preferred embodiment of the present invention. 
     FIG.  3  and FIG. 4 show a pair of schematic diagrams illustrating operation of a fuel tank filler pipe neck assembly in accord with a second preferred embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG.  1  and FIG. 2, there is shown a pair of schematic diagrams illustrating operation of a fuel tank filler pipe neck assembly within a fuel system in accord with a first preferred embodiment of the present invention. Shown in FIG. 1 is a schematic diagram of the fuel system at an earlier point in operation of the fuel tank filler pipe neck assembly. 
     Shown in FIG. 1 is a fuel tank  10  having incorporated therein a fuel tank filler pipe  12  which is employed for introducing a liquid fuel  20   a  into the fuel tank  10 . Within the fuel tank  10 , the liquid fuel  20   a  has formed thereover a fuel vapor  20   b.  At a distal end of the fuel tank filler pipe  12  with respect to the fuel tank  10  there is illustrated a fuel tank filler pipe neck assembly  22 . There is also shown within the schematic diagram of FIG. 1 further with respect to the fuel tank  10 : (1) a fuel tank fuel vapor vent pipe  14  which vents the fuel vapor  20   b  from the fuel tank  10  when refueling the fuel tank  10  with the liquid fuel  20   a;  and (2) a fuel tank fuel level sensor  16  which is similarly further in fluid communication with the fuel tank filler pipe neck assembly  22 . 
     Within the first preferred embodiment of the present invention with respect to the fuel tank level sensor  16 , and as illustrated within the schematic diagram of FIG. 1, the fuel tank level sensor  16  comprises a hollow member, such as but not limited to a tube, one end of which penetrates into the fuel tank  10  and the other end of which terminates within the fuel tank filler pipe neck assembly  22 . Operation of the fuel tank level sensor  16  is discussed in greater detail below. 
     Within the first preferred embodiment of the present invention with respect to the fuel tank filler pipe neck assembly  22 , the fuel tank filler pipe neck assembly  22  comprises in a first instance a first chamber  30  having formed therein a liquid fuel dispensing nozzle entry port (illustrated by implication) through which is introduced a liquid fuel dispensing nozzle  18  and a liquid fuel exit port (also illustrated by implication) through which exits the liquid fuel  20   a  which is dispensed by the liquid fuel dispensing nozzle  18 . Similarly, with respect to the fuel tank filler pipe neck assembly  22  and contained within the first chamber  30  is a liquid fuel dispensing nozzle seat  24  upon which is seated and sealed a rim of the liquid fuel dispensing nozzle  18  while dispensing the liquid fuel  20   a  therefrom, and while allowing the liquid fuel  20   a  to pass through the liquid fuel dispensing nozzle seat  24 . Similarly, there is also shown within the schematic diagram of FIG. 1 with respect to the first chamber  30  and the liquid fuel dispensing nozzle seat  24  a resilient and flexibly biased sealing means  26  further sealing the liquid fuel dispensing nozzle seat  24  with respect to the liquid fuel exit port of the first chamber  30 . 
     Within the first preferred embodiment of the present invention with respect to the resilient and flexibly biased sealing means  26 , although the schematic diagram of FIG. 1 illustrates the resilient and flexibly biased sealing means  26  as nominally formed of a spring  26   a  surrounding a flexible curtain  26   b  typically and preferably formed of a liquid fuel  20   a  impervious material, other resilient and flexibly biased sealing means may be employed when fabricating the resilient and flexibly biased sealing means  26 . In that regard, for example and without limitation, the resilient and flexibly biased sealing means  26  may also be formed as a laminated construction which incorporates both a resilient bias means and a flexible sealing means into a single component. Similarly, and also for example and without limitation, within the present invention and the first preferred embodiment of the present invention the flexible curtain  26   b  may be formed surrounding the spring  26   a.  Important to the present invention is that the resilient and flexibly biased sealing means  26  actually be resilient (i.e., elastic) and flexible (i.e., able to be deformed in multiple directions) such as to accommodate variations of seating of the liquid fuel dispensing nozzle  18  with respect to the liquid fuel dispensing nozzle seat  24 . Finally, although the preferred embodiment of the present invention also illustrates the liquid fuel dispensing nozzle seat  24  and the resilient and flexibly biased sealing means  26  as separate components, they too may also be fabricated as a single integral component. 
     As is illustrated within the schematic diagram of FIG. 1, since the liquid fuel dispensing nozzle seat  24  and the resilient and flexibly biased sealing means  26  effectively seal a flow of liquid fuel  20   a  from the liquid fuel dispensing nozzle  18  when dispensing the liquid fuel  20   a  from the liquid fuel dispensing nozzle  18  into the fuel tank filler pipe  12 , within the context of the present invention and the first preferred embodiment of the present invention there is no adventitious air or fuel vapor entrained into the liquid fuel  20   a  dispensed from the liquid fuel dispensing nozzle  18  and thus there is minimized formation of additional fuel vapor  20   b  within either the fuel tank  10  or the first chamber  30  when dispensing liquid fuel  20   a  from the liquid fuel dispensing nozzle  18 . 
     However, and also within the context of the present invention and the first preferred embodiment of the present invention, since the liquid fuel dispensing nozzle  18  is effectively seated against the liquid fuel dispensing nozzle seat  24  and sealed with respect to the liquid fuel exit port of the first chamber  30 , there is also absent within the present invention and the first preferred embodiment of the present invention a splashing of the liquid fuel  20   a  against a vacuum sensing port  36  of the liquid fuel dispensing nozzle  18 , which splashing would otherwise trigger a shut down of the liquid fuel dispensing nozzle  18  when the fuel tank  10  is filled with liquid fuel  20   a.    
     Thus, in order to effectively shut down the liquid fuel dispensing nozzle  18  when the liquid fuel  20   a  within the fuel tank  10  reaches an appropriately high level, the fuel tank filler pipe neck assembly  22  of the present invention employs an alternative means which is not predicated upon a splashing of liquid fuel  20   a  against the vacuum sensing port  36  of the liquid fuel dispensing nozzle  18 . Within the context of the first preferred embodiment of the present invention, the alternative means comprises a second chamber  32  annular to the liquid fuel dispensing nozzle  18  and further in fluid communication with the fuel tank fuel level sensor  16 . As is illustrated within the schematic diagram of FIG. 1, the second chamber  32  is enclosed with an unbiased annular sealing means  34  (i.e., illustrated specifically as a diaphragm) which may be formed of a flexible sealing material analogous or equivalent to the flexible sealing material from which is formed the flexible curtain  26   b.  The unbiased annular sealing means  34  when unbiased as illustrated within the schematic diagram of FIG. 1 allows entry of air, gas or vapor (i.e., an uncondensed make-up fluid) into the first chamber  30  such that the vacuum sensing port  36  of the liquid fuel dispensing nozzle  18  experiences no vacuum and thus liquid fuel  20   a  is continuously dispensed from the liquid fuel dispensing nozzle  18 . 
     As is further illustrated within the schematic diagram of FIG. 2, under circumstances when the fuel tank  10  is sufficiently filled with the liquid fuel  20   a  such that the liquid fuel  20   a  covers the fuel tank fuel level sensor  16 , there is provided a pressure head to a volume of gas or vapor within the second chamber  32  such that the unbiased annular sealing means  34  as illustrated in FIG. 1 is pressure biased to form the pressure biased annular sealing means  34 ′ which effectively annularly seals the liquid fuel dispensing nozzle  18  within the first chamber  30  such that the vacuum sensing port  36  of the liquid fuel dispensing nozzle  18  senses a vacuum which shuts down the liquid fuel dispensing nozzle  18 . 
     Referring now to FIG.  3  and FIG. 4, there is shown a pair of schematic diagrams illustrating operation of a fuel tank filler pipe neck assembly in accord with a second preferred embodiment of the present invention. Shown in FIG. 3 is a schematic diagram of the fuel tank filler pipe neck assembly at an early stage in its operation in accord with the second preferred embodiment of the present invention. 
     Shown in FIG. 3 is a schematic diagram of a fuel tank filler pipe neck assembly generally equivalent to the fuel tank filler pipe neck assembly  22  whose schematic diagram is illustrated in FIG. 1, but without illustration of a fuel tank  10  which otherwise equivalently connects with a fuel tank filler pipe  12  and a fuel tank fuel level sensor  16  as illustrated within the fuel tank filler pipe neck assembly whose schematic diagram is illustrated in FIG.  3 . Within the fuel tank filler pipe neck assembly whose schematic diagram is illustrated in FIG. 3, in comparison with the fuel tank filler pipe neck assembly  22  whose schematic diagram is illustrated in FIG. 1, equivalent elements and structures are numbered equivalently while analogous elements and structures are numbered analogously, but denoted with a prime. 
     As is illustrated within the schematic diagram of FIG. 3, the liquid fuel dispensing nozzle  18  is sealed within a first chamber  30 ′ by means of an annular sealing means  38  located at a liquid fuel dispensing nozzle entry port of a first chamber  30 ′. Similarly with the first preferred embodiment of the present invention, as illustrated within the schematic diagram of FIG. 1, the liquid fuel dispensing nozzle  18  is seated upon a liquid fuel dispensing nozzle seating means  24  which is further sealed with respect to a liquid fuel exit port of the first chamber  30 ′ by means of a resilient and flexibly biased sealing means  26 . 
     In contrast with the first preferred embodiment of the present invention, within the second preferred embodiment of the present invention, air, gas or vapor (i.e., the uncondensed make-up fluid) is supplied to a vacuum sensing port  36  of the liquid fuel dispensing nozzle  18  through means of a first chamber vent tube  42  which is generally counter-opposed to a second chamber  32 ′ having formed thereupon an unbiased areal sealing means  40  (i.e., also specifically illustrated as a diaphragm), and wherein the second chamber  32 ′, similarly with the second chamber  32  within the first preferred embodiment of the present invention, is in fluid communication with the fuel tank fuel level sensor  16 . 
     Referring now to FIG. 4, there is shown a schematic diagram illustrating the results of further operation of the fuel tank filler pipe neck assembly whose schematic diagram is illustrated in FIG.  3 . 
     Shown in FIG. 4 is a schematic diagram of a fuel tank filler pipe neck assembly otherwise equivalent to the fuel tank filler pipe neck assembly whose schematic diagram is illustrated in FIG. 3, but wherein, and analogously with the fuel tank filler pipe neck assembly whose schematic diagram is illustrated in FIG. 2, a volume of vapor or gas within the second chamber  32 ′ has been compressed by a pressure head of a sufficiently high liquid fuel level within a fuel tank (not shown), such that the unbiased areal sealing means  40  is transformed to a pressure biased areal sealing means  40 ′ which seals an air, gas or vapor flow through the first chamber vent tube  42  such that the vacuum sensing port  36  of the liquid fuel sensing nozzle  18  senses a vacuum and thus shuts down the liquid fuel dispensing nozzle  18 . 
     As is understood by a person skilled in the art, the preferred embodiments of the present invention are illustrative of the present invention rather than limiting of the present invention. Revisions and modifications may be made to materials components and dimensions through which is provided in accord with the preferred embodiments of the present invention a fuel tank filler pipe neck assembly, a fuel system or a method for filling a fuel tank in accord with the present invention, further in accord with the appended claims.

Technology Category: 7