Patent Publication Number: US-2018038320-A1

Title: Multi-stage check valve for vapor recirculation line of liquid containment system

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to liquid containment systems. More specifically, aspects of this disclosure relate to fuel storage systems with vapor recirculation and vapor capture capabilities for motor vehicles. 
     BACKGROUND 
     A wide array of storage tanks, drums and other fluid-tight containers are used for holding and transporting various types of fluids. As an example, most conventional motor vehicles, such as the modern-day automobile, are originally equipped with an onboard fuel tank for safely storing combustible petroleum-based fuels, such as gasoline and diesel fuel, for use by an internal combustion engine (ICE) assembly. Portable fuel containers, more commonly known as “gas cans” or colloquially as “gas caddies” in some countries, are also available for manually transporting smaller quantities of fuel. Liquefied gas tanks, on the other hand, are stationary containers used to store liquefied petroleum gases, such as propane, propylene, butanes, and butylenes, for use in both industrial and residential applications. 
     Vehicle fuel tanks are traditionally refilled at public gas stations, also known as filling stations, petrol stations, and petrol garages. Most vehicle fuel tank systems have a fill pipe with a fill cup that is designed to receive a fill pump nozzle that replaces the contents of the fuel tank. To reduce spillage during refilling, nearly all fill pump nozzles include a fill-limiting sensor for discontinuing the flow of fuel from the nozzle when the fuel in the tank reaches a predetermined volume. Typically, such fill-limiting sensors are triggered when the fuel tank is full, and fuel begins to “back up” the filler neck to reach or spray the fill-limiting sensor. To reduce hydrocarbon vapor emissions during and after refilling, many fuel tank systems employ an in-line vapor canister for capturing vapor that is emitted from the fuel tank. The captured vapor is stored by the vapor canister for future consumption by the engine as the vehicle is operated. 
     When the fuel fill cup is exposed for refueling, e.g., after opening a protective fuel door and/or removing a gas cap, and when fuel is flowing from the fill pump nozzle into the fill pipe, a flexible seal is positioned within some prior art fill cups to prevent the escape of hydrocarbon vapor from the tank through the fill cup that would otherwise bypass the vapor canister. In some arrangements, a recirculation line is fluidly connected at one end to an upper wall of the fuel tank and at another end to the fill pipe below the mechanical seal. The recirculation line permits fuel vapor to be recirculated from the tank through the fill pipe and back into the incoming flow of fuel. This reduces air entrainment by displacing outside air with fuel vapor. In so doing, the recirculation line helps to facilitate flow of the liquid fuel into the fuel tank and concomitantly minimize the discharge of fuel vapor out through the fill pipe to the atmosphere. 
     SUMMARY 
     Disclosed herein are liquid containment systems with multi-stage check valves for controlling fluid flow within vapor recirculation lines, methods for making and methods for using such liquid containment systems, and motor vehicles with fuel storage systems employing two-stage check valves for regulating recirculating vapor volume through fuel vapor recirculation lines. By way of non-limiting example, an improved two-stage unidirectional check valve is inserted into a fuel vapor recirculation line, e.g., interposed between the fuel tank and fill cup, or mounted directly to the fuel tank, e.g., interposed between the recirculation line and interior compartment of the fuel tank. At low fill rates, typically flowing at approximately 4 to 5 gallons/minute or less, in-tank pressures are relatively low (e.g., about 0.25 to 1.25 kilopascal (kPa)); the check valve&#39;s spring-biased plunger remains seated such that recirculation vapor flow is limited to passing through a central bleed hole in the plunger. Contrastingly, at high fill rates, e.g., ranging from approximately 8 to 10 gallons/minute, the in-tank pressures are sufficiently high (e.g., 1.25 kPa and above) to unseat and displace the valve plunger. By overcoming the spring force and displacing the plunger, additional recirculating vapor is allowed to flow around the plunger in addition to flow through the hole in the plunger. A reduced-diameter flow restrictor can be added to the vapor canister to increase in-tank pressures during refilling. 
     Attendant benefits for at least some of the disclosed concepts include the ability to dynamically manage fill-pipe recirculation flow volume with a dedicated multi-stage spring-loaded check valve assembly. The check valve assembly helps to minimize hydrocarbon vapor generation in the fuel tank during gas station refueling by recirculating an optimal volume of vapor for each of multiple fill rates. By saturating the incoming fuel with an optimal volume of existing fuel vapor, a reduced amount of outside air can become entrained with the incoming fuel such that a minimized amount of new vapor is generated. Advantageously, at least some of the disclosed systems ensure that the average vapor introduced into the liquid containment tank during refill is reduced to approximately 4.5 g/gal or less. Disclosed configurations can be easily integrated to efficiently and effectively minimize vapor generation even as vapor canister purge capabilities decrease industry-wide with newer and more efficient powertrains. Other attendant benefits can include lower system costs when compared to conventional measures, such as mechanical seals, vent valves, etc., that are used to address hydrocarbon vapor emissions. By simplifying the overall system architecture, the vapor recirculation system is more robust and, thus, less prone to warranty problems, such as failed nozzle tank pressure issues. 
     Aspects of the present disclosure are directed to liquid containment systems with vapor recirculation and vapor capture capabilities. Disclosed, for example, is a liquid containment system for stowing a hydrocarbon-based liquid discharged from a fill nozzle. This liquid containment system includes a liquid container with a vapor canister fluidly coupled to the liquid container. The vapor canister receives and stores hydrocarbon vapor from hydrocarbon-based liquid stowed in the liquid container. A fill conduit, which is fluidly coupled to the liquid container, has an open end for receiving hydrocarbon-based liquid from the fill nozzle. A vapor recirculation conduit is fluidly coupled to the liquid container and to the fill conduit proximate the open end thereof. The vapor recirculation conduit transmits hydrocarbon vapor from the liquid container to the fill conduit. The liquid containment system also includes a multi-stage check valve assembly that is fluidly coupled to the liquid container and vapor recirculation conduit. The check valve assembly has a housing and a plunger with a bleed hole. The plunger is movable within the housing to transition back-and-forth between a first (seated) position and a second (unseated) position. When in the first position, the plunger seats against the housing such that hydrocarbon vapor passes from the liquid container through only the bleed hole to the fill conduit via the vapor recirculation conduit. Contrastingly, when in the second position, the plunger unseats from the housing such that hydrocarbon vapor passes from the container through the bleed hole and around the plunger to the fill conduit via the recirculation conduit. 
     Other aspects of the present disclosure are directed to motor vehicles with fuel storage systems having vapor recirculation and vapor capture capabilities. A “motor vehicle,” as used herein, may include any relevant vehicle platform, such as passenger vehicles (internal combustion engine (ICE), hybrid, electric, fuel cell, etc.), commercial vehicles, industrial vehicles, tracked vehicles, all-terrain vehicles (ATV), farm equipment, motorcycles, boats, airplanes, spacecraft, etc. In an example, a motor vehicle is disclosed that includes an engine mounted to a vehicle body, a fuel tank fluidly coupled to the engine, and a vapor line fluidly coupled to the fuel tank. A vapor canister, which is fluidly coupled to the fuel tank via the vapor line, receives hydrocarbon vapor from fuel stowed in the interior space of the fuel tank, stores the vapor, and purges the vapor to the engine. A fill pipe has a first end fluidly coupled to the fuel tank and a second end fluidly coupled to a fill cup. This fill cup is designed to receive a fill pump nozzle. 
     The motor vehicle also includes a vapor recirculation line with a first end fluidly coupled to the fuel tank, e.g., via the vapor line, and a second end fluidly coupled to the fill cup. The vapor recirculation line transmits hydrocarbon vapor from the fuel tank into the fill pipe via the fill cup. A one-way two-stage check valve assembly is fluidly coupled to the fuel tank and vapor recirculation line. The check valve assembly has an elongated housing, a spring packaged inside the housing, and a plunger with a bleed hole. The plunger slides back-and-forth within the housing between first and second positions. When in-tank vapor pressure is sufficiently low, the spring biases the plunger towards the first position to seat against the housing such that hydrocarbon vapor passes from the fuel tank through only the bleed hole to the fill cup via the vapor recirculation line. When in-tank vapor pressure exceeds the bias force of the spring, the plunger unseats from the housing and moves to the second position such that hydrocarbon vapor passes through the bleed hole and around the plunger to the fill cup. 
     In yet other aspects of the present disclosure, methods for making and methods for using liquid storage containers are presented. For instance, a method of constructing a liquid containment system for stowing a hydrocarbon-based liquid discharged from a fill nozzle is disclosed. The method includes, in any order and in any combination: fluidly coupling a vapor canister to a liquid container, the vapor canister being configured to receive and store hydrocarbon vapor from the hydrocarbon-based liquid stowed in the liquid container; fluidly coupling a fill conduit to the liquid container, the fill conduit having an open end configured to receive the hydrocarbon-based liquid from the fill nozzle; fluidly coupling a vapor recirculation conduit to the liquid container and to the fill conduit proximate the open end thereof, the vapor recirculation conduit being configured to transmit hydrocarbon vapor from the liquid container to the fill conduit; and fluidly coupling a multi-stage check valve assembly to the liquid container and the vapor recirculation conduit, the check valve assembly having a housing and a plunger with a bleed hole, the plunger being movable within the housing to transition between a first position, whereat the plunger seats against the housing such that hydrocarbon vapor passes from the liquid container through only the bleed hole to the fill conduit via the vapor recirculation conduit, and a second position, whereat the plunger unseats from the housing such that hydrocarbon vapor passes through the bleed hole and around the plunger to the fill conduit. The method may also include fluidly coupling a flow restrictor between the liquid container and the vapor canister. The flow restrictor is designed to increase the internal pressure within the liquid container. The method may also include fluidly coupling a vapor generation reduction device (VGRD) to the fill conduit. The VGRD regulates in-flow fluid speed and turbulence of the hydrocarbon-based liquid discharged from the fill nozzle. 
     The above summary is not intended to represent every embodiment or every aspect of the present disclosure. Rather, the foregoing summary merely provides an exemplification of some of the novel aspects and features set forth herein. The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of representative embodiments and modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevated perspective-view illustration of a representative liquid containment system having a vapor canister and a vapor recirculation line with a two-stage check valve in accordance with aspects of the present disclosure. 
         FIG. 2  is a cross-sectional side-view illustration of the representative two-stage check valve of  FIG. 1 . 
         FIG. 3  is a perspective-view illustration of the representative fill pipe and vapor recirculation line of  FIG. 1  with an inset view showing a vapor generation reduction device (VGRD) disposed between the fill cup and storage tank. 
     
    
    
     The present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms disclosed in the drawings. Rather, the disclosure is to cover all modifications, equivalents, combinations, subcombinations, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     This disclosure is susceptible of embodiment in many different forms. There are shown in the drawings and will herein be described in detail representative embodiments of the disclosure with the understanding that the present disclosure is to be considered as an exemplification of the principles of the disclosure and is not intended to limit the broad aspects of the disclosure to the embodiments illustrated. To that extent, elements and limitations that are disclosed, for example, in the Abstract, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference or otherwise. For purposes of the present detailed description, unless specifically disclaimed: the singular includes the plural and vice versa; the words “and” and “or” shall be both conjunctive and disjunctive; the word “all” means “any and all”; the word “any” means “any and all”; and the words “including” and “comprising” and “having” mean “including without limitation.” Moreover, words of approximation, such as “about,” “almost,” “substantially,” “approximately,” and the like, can be used herein in the sense of “at, near, or nearly at,” or “within 3-5% of,” or “within acceptable manufacturing tolerances,” or any logical combination thereof, for example. 
     Referring now to the drawings, wherein like reference numbers refer to like features throughout the several views, there is shown in  FIG. 1  a perspective-view illustration of a representative liquid containment system for stowing hydrocarbon-based liquids. This system, which is designated generally at  10 , is represented herein for purposes of a more detailed discussion as a motor vehicle fuel storage system, e.g., for a passenger car, commercial vehicle or other automobile. The specific architecture of the liquid containment system  10  illustrated in  FIG. 1 —also referred to herein as “fuel storage system”—is merely an exemplary application with which the novel aspects of this disclosure can be practiced. In the same vein, the implementation of the present concepts into an automobile fuel system should also be appreciated as an exemplary application of the novel concepts disclosed herein. As such, it should be understood that the aspects and features of the present disclosure can be integrated into other liquid containment applications and can be utilized for any logically relevant type of motor vehicle. Lastly, the drawings presented herein are not necessarily to scale and are provided purely for instructional purposes. Thus, the specific and relative dimensions shown in the drawings are not to be construed as limiting. 
     According to the illustrated example, the fuel storage system  10  includes a fuel tank  12  (also referred to herein as “liquid container”) with bolt flanges  14  for mounting to a vehicle body, and a tank meter  16  for measuring a fuel level inside the tank  12 . Fuel tank  12  has a fluid-tight compartment  18  for stowing a hydrocarbon based fuel, such as diesel or gasoline fuel. While any suitable size and shape can be employed, the fuel tank  12  of  FIG. 1  has a 14-gallon capacity with a generally rectangular, oblong shape composed of opposing top and bottom walls  11  and  13 , respectively, connected by a sidewall  15 . A fuel fill pipe  20  (also referred to as “fill conduit” or “filler neck”) is fluidly coupled at a first (lower) end thereof to the fuel tank  12  via elbow pipe  22 . A second (open upper) end of the fill pipe  20  is fluidly coupled to a fill cup  24 , which is shaped and sized to receive therein at least the spout end of a conventional fill pump nozzle (not shown). Fuel is fed to the fuel tank  12  from the nozzle through the fill cup  24 , then fill pipe  20  and lastly into elbow pipe  22 . 
     Vapor capture and vapor recirculation capabilities are provided by hydrocarbon vapor capture and hydrocarbon vapor recirculation subsystems  26  and  28 , respectively. A vapor line or conduit  30  fluidly connects the fuel tank  12  to a vapor canister  32 , which allows evaporative emissions, namely hydrocarbon vapor, to be vented from the fuel tank  12  to the vapor canister  32 . This vapor canister  32  absorbs and stores fuel vapor from within the fuel storage system  10 . An internal combustion engine (ICE) assembly, shown schematically at  34 , draws fuel vapors purged from the vapor canister  32 , e.g., via a purge pump through a dedicated purge line, into an intake manifold to fuel the engine  34  as needed. The vapor canister  30  may be in the nature of, but is certainly not limited to, an activated-carbon packed canister, an activated-charcoal canister, or other known or hereinafter developed evaporative emissions canister suitable for absorbing fuel vapors in a fuel storage system. For activated-carbon canister configurations, average pore radius of the packed carbon is typically in the range of from about 12.0 to about 14.0 Angstroms, with particle diameters ranging from about 1.6 to about 3.0 mm. Heating elements activate the packed carbon for desired absorption and desorption performance. Unlike many conventional carbon canisters, the vapor canister  32  of  FIG. 1  can be characterized by a lack of a bleed valve or similar structure for purging vapor to the atmosphere. In the same vein, the vapor canister  32  may be configured with a fresh-air port but designed to prevent/eliminate vapor breakthrough. 
     To prevent the escape of vaporized fuel from the fuel tank  12  through fill cup  24  of  FIG. 1 , as well as to minimize the unwanted generation of new vapor during refilling of the liquid containment system  10 , a vapor recirculation line  36  permits fuel vapor to be recirculated up from the tank  12  through the fill cup  24 , and back into the fill pipe  20  to mix with the incoming flow of fuel. A first (lower) end of vapor recirculation line  36  is fluidly coupled to the top wall  11  of the fuel tank  12 , e.g., via fluid junction  38  to vapor line  30 . Conversely, a second (upper) end of the vapor recirculation line  36  is fluidly coupled directly to the fill cup  24 , e.g., below the spout opening at the upper-most end of the cup. A functional diameter of the recirculation line  36  is noticeably smaller than the functional diameter of the vapor line  30 , as can be inferred from  FIG. 1 ; thus, vapor will have a natural propensity to evacuate from the tank  12  to the vapor canister  32 . During refilling, however, the aspirating effect of incoming liquid flow reduces the pressure in the fill cup  24 . This creates a pressure differential that, once sufficiently large, diverts hydrocarbon vapor from the vapor line  30  into the vapor recirculation line  36 . The recirculation line  36  then transmits this vapor from the fuel tank  12  to the fill pipe  20  via the fill cup  24 . It may also be desirable, for at least some configurations, that vapor be transmitted by the recirculation line  36  from the fill head cup  24  to the vapor canister  32  during low in-tank pressures. As another optional configuration, the traditional mechanical filler nozzle seal that is typically disposed within many conventional fill cups to seal around the spout end of the fill pump nozzle can be altogether eliminated from the system architecture of  FIG. 1 . 
     Hydrocarbon vapor recirculation subsystem  28  provides dynamic control of recirculation flow volume to the fill pipe  20  using a multi-stage check valve assembly  40 . In the architecture illustrated in  FIG. 1 , the check valve assembly  40  is interposed between the fuel tank  12  and fill pipe  20 , integrated into the vapor recirculation line  40  fluidly upstream from the fluid-tight compartment  18  and fluidly downstream from the fill cup  24 . It is also envisioned that the check valve assembly  40  be welded or otherwise attached directly to the fuel tank  12  fluidly upstream from and fluidly coupled to the vapor recirculation line  40 . Other packaging locations within the liquid containment system  10  are deemed to be within the scope and spirit of the present disclosure. As another optional alternative, to support on-board vehicle diagnostics the check valve assembly  40  may be configured as a two-way valve assembly that allows vapor to flow, in a controlled manner, both towards and away from fill cup  24 . Check valve assembly  40  more accurately tunes recirculation flow volume to ensure fuel flowing at high velocity down the fill pipe  20  is substantially or fully entrained with vapor rather than fresh air. In so doing, vapor generation is reduced because liquid fuel mixed with fuel vapor is typically unable to produce additional fuel vapor. 
     With reference to  FIG. 2 , the illustrated check valve assembly  40  has an elongated, tube-like bipartite housing composed of a valve body cover  44  that is attached to a cylindrical main valve body  42  to cooperatively define an internal cavity  41 . As shown, the valve cover  44  includes an annular male attachment interface  50  that receives therein and snap-fits to an annular female attachment interface  52  of the valve body  42 . As some alternative examples, the valve cover  44  can be operatively attached to the valve body  42  by alternative means, such as helical threads, adhesives, quick-lock connectors, etc., or may be integrally formed as a single-piece, unitary structure. Extending through a longitudinal end of the housing&#39;s main body  42  is an inlet opening  43  for receiving hydrocarbon vapor from the fuel tank  12 , e.g., via vapor line  30  and recirculation line  36 . An outlet opening  45  extends through the valve body cover  44  and fluidly connects to the inlet opening  43  via internal cavity  41 ; hydrocarbon vapor is expelled from the check valve assembly  40  via outlet opening  45 . Each end of the valve housing  42 ,  44  includes respective line coupling adaptors  43  and  45  with one or more toroidal or helical teeth for ready installation into the vapor recirculation line  36 . 
     A biasing member, represented herein as a helical spring  46 , is packaged inside the internal cavity  41 , compressed between the valve body  42  and valve cover  44 . It should be appreciated that the biasing member may take on other forms, including leaf springs, torsional springs, electronically controlled linear actuators, etc., within the scope of this disclosure. A flow-control plunger  48 , which includes a central bleed hole  49 , is fixed to one end of the spring  46 . This plunger  48  slides back-and-forth along a linear path (e.g., left-to-right in  FIG. 2 ) within the internal cavity  41  of the housing  42 ,  44 . Main valve body  42  includes an annular plunger shoulder  51  against which the plunger  48  seats under the biasing force of the spring  46 . Likewise, the valve body cover  44  includes an annular spring shoulder  53  against which the spring seats to bias the plunger from the second position to the first position. Both the plunger shoulder  51  and spring shoulder  53  extend radially inward into the housing&#39;s internal cavity  41 , each having a central through-hole for allowing passage of fuel vapor. In the illustrated example, the plunger  48  has a hollow cylindrical body  55  with a disk-shaped cap  57  at one end thereof. The bleed hole  49  extends through the center of the cap  57 . The shape, size and relative proportions of the spring  46  and plunger  48  can be varied, individually or collectively, to accommodate the design parameters of different applications. For instance, the bleed hole  49  diameter, cap  57  dimensions, spring pre-load, and/or spring rate of spring  46  can be tailored to selectively tune tank pressure and recirculation flow with a high degree of accuracy and precision. 
     The plunger  48  reciprocates back-and-forth within the housing&#39;s internal cavity  41  between a first (seated) position and a second (unseated) position. When in the first position, shown in  FIG. 2  with solid-line plunger  48 , the spring  46  biases the plunger  48  to press against the housing&#39;s plunger shoulder  51 . Seating the plunger  48  against the plunger shoulder  51  constricts hydrocarbon vapor flow HV to pass through only the bleed hole  49  in cap  57 . Thus, vapor flow HV passing from the fuel tank  12  through the check valve assembly  40  to the fill cup  24  via the vapor recirculation line  36  is restricted to a first (reduced) flow rate. In contrast, when in-tank vapor pressure is sufficiently high to generate a line pressure force against the plunger cap  57  that exceeds the bias force of the spring  46 , the plunger  48  translates rectilinearly to the second position, shown in  FIG. 2  with hidden-line plunger  48 A. Unseating the plunger  48  from the plunger shoulder  51  allows hydrocarbon vapor flow HV to pass both through the bleed hole  49  and around the plunger  48 , e.g., via expanded diameter section  59  of the main valve body  42 . Thus, vapor flow HV passing from the fuel tank  12  through the check valve assembly  40  to the fill cup  24  via the vapor recirculation line  36  is amplified to a second (increased) flow rate. According to the illustrated example, an optional flow restrictor  54  ( FIG. 1 ), which may be in the nature of a reduced-diameter restriction, is fluidly interposed between the liquid container  12  and vapor canister  32 . This flow restrictor  54  increases the internal pressure within the fuel tank  12  to modulate the operability of the check valve  40 . In addition, an optional vapor generation reduction device (VGRD)  56  ( FIG. 3 ) is fluidly coupled to fuel fill pipe  20 , e.g., interposed between pipe  20  and elbow pipe  22 . VGRD  56 , which may be in the nature of an aerator plug, regulates in-flow fluid speed and turbulence of the hydrocarbon-based liquid discharged from the fill pump nozzle. 
     Vapor recirculation subsystem  28  helps to optimize the amount of recirculated fuel vapor in the fill pipe  20  to reduce fuel vapor generation and minimize vapor to the canister  32 . Minimizing vapor to the canister  32  can be essential, e.g., for small displacement, turbocharged engines with limited ability to purge large amounts of fuel vapor from the vapor canister. At low fill rates (e.g., ca. 4 gals/min or less), in-tank pressures are sufficiently low such that the check valve assembly  40  remains closed and vapor flows only through the bleed hole  49  in the plunger  48 . At high fill rates (e.g., ca. 10 gals/min), in-tank pressures are sufficiently high such that the check valve assembly  40  opens and allows vapor flow around the plunger  48  in addition to the flow through bleed hole  49 . During a refueling event, incoming fuel running down the fill pipe  20  tends to entrain outside air which typically generates extra vapor. With the system of  FIG. 1 , fuel vapor is recirculated to the top of the fill pipe  20  to sufficiently saturate incoming fuel with hydrocarbon vapor and thereby reduce the amount of new vapor generated. Using the two-stage check valve assembly  40  helps to ensure a maximum amount of vapor is recirculated into the fill pipe under changing operating conditions. 
     While aspects of the present disclosure have been described in detail with reference to the illustrated embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise construction and compositions disclosed herein; any and all modifications, changes, and variations apparent from the foregoing descriptions are within the spirit and scope of the disclosure as defined in the appended claims. Moreover, the present concepts expressly include any and all combinations and subcombinations of the preceding elements and aspects.