Vehicle Fuel Tank Vapor Recovery System

The present invention relates to fuel vapor recovery systems for vehicles.

Evaporative loses of hydrocarbons from motor fuel tanks contribute significantly to the unburned hydrocarbons emitted to the atmosphere. In 1991, the Environmental Protection Agency plans to require each vehicle manufacturer to provide an on-board method of recovering fuel vapors during a fuel refilling process. For safety reasons, such method must also provide for closing the vapor recovery line after completing the refueling process to prevent fuel from escaping during a collision or rollover. Automobile manufacturers desire, of course, to effect these ends with minimum changes to the vehicle and minimum changes to the customary refueling sequence.

In view of the above, and in accordance with the present invention, there is provided a fuel vapor recovery system which allows the fuel tank filler neck to be sealed during the fill phase of operation such that vapors generated during the fill phase can be directed to an evaporative control canister.

With the present invention, the physical installation and removal of the sealant member or gas cap is the activator of the system. More specifically, the present invention offers a valve assembly which is mounted in the fuel filler tube and is positionally responsive to the presence or removal of the sealant member or gas cap. The valve assembly of the present invention is disposed in combination with a vapor vent line leading to a fuel vapor canister. Broadly stated, the valve assembly includes first and second sealant means disposed on opposite sides of the vapor vent port. The first sealant means blocks or prevents communication between the atmosphere and the interior of the fuel tank when the gas cap is removed and the fuel nozzle is disposed in the filler tube. The second sealant means permits communication between the unrestricted vent port and the fuel tank interior when the gas cap or closure means is removed from the open ended filler tube and blocks communication between the fuel tank's interior and the vapor vent when the cap assembly is reinstalled. By such construction, the valve assembly of the present invention is capable of controlling vapor passage from the tank as a function of gas cap disposition.

Accordingly, a primary object of this invention is to improve collection of fuel vapor emissions generated from refueling a vehicle's fuel supply system while maintaining the same customer perception in the refueling sequence, maximizing the safety aspect in potential collision conditions, and minimizing vehicle changes.

Another object of this invention is the provision of a fuel vapor recovery means which controls vapor escapement from the tank as a function of the filler cap's disposition.

A further object of this invention is to provide a vapor vent valve assembly which includes a positionally responsive valve arrangement which responds to filler cap disposition.

Having in mind the above objects and other attendant advantages that would be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangement of parts as illustrated in the presently preferred forms of the invention which are hereinafter set forth in detail to enable those skilled in the art to readily understand the function, operation, construction and advantages of same when read in conjunction with the accompanying drawings in which;

FIG. 1 is a cross-sectional view of one embodiment of a fuel vapor recovery valve assembly which incorporates the teachings of the present invention; and

FIG. 2 is a cross-sectional view of a second embodiment of a fuel vapor recovery valve assembly incorporating the teachings of this invention.

Referring now to the drawings, FIG. 1 illustrates a fuel filler system including an open ended fuel tank filler tube 10 leading from and connected to a fuel tank 12 carried by a vehicle 14. The fuel tank 12 has an interior fuel space 16 into which tube 10, ultimately, opens. The filler tube 10 is provided with an unrestricted vent port 18 which permits communication between the interior space 16 of tank 12 and a vapor collection canister 20 sized to be easily located on the vehicle. The canister may be of a conventional configuration having an interior volume or cavity 21 filled at least in part with an active vapor absorbing material such as activated charcoal. A threaded, ratchet type seal cap assembly or closure member 22 is provided for opening and sealing off or closing the open end 23 of the filler tube depending on the disposition of the cap assembly.

The present invention relates to the provision of a positionally responsive operative assembly 24 disposed in the interior of the filler neck 10 in combination with the vent port 18 for controlling the escapement of fuel vapors during a fuel filling process. One salient feature of this invention being that the operative means for controlling fuel vapor escapement from the fuel tank operates as a function of the filler cap disposition.

The operative assembly 24 includes an elongated spool like member or body 26 non-rotatably arranged in the filler tube 10 for axial endwise displacement. In the embodiment illustrated in FIG. 1, member 26 includes end portions 28 and 30 joined by a center section 32 and defines a central or axial bore 34 extending therethrough. The center section 32 has a smaller diameter than the two end portions 28 and 30. As a result of the different diameter portions, a first shoulder or seat 36 is established between end section 28 and center section 32. A second shoulder or seat 38 is established between end section 30 and center section 32. The bore extending through the first section 28 is enlarged and includes a series of internal threads or elements 40 which are adapted to cooperate and interengage with a threaded portion of closure cap assembly 22. By such construction, when the cap 22 is rotated with respect to the operative assembly 24, the member or body 26 will move endwise in one direction or another depending on the direction of rotation imparted to the cap assembly 22.

In the illustrated embodiment, the body or member 26 is normally urged in an axial direction away from the open end of filler tube 10 by a resilient member or spring 42. As such, when the sealing cap assembly 22 is removed from threaded engagement with the operative assembly during the fuel filling process, member 26 is automatically moved away from the open end of the filler tube under the influence of the resilient means 42.

Fixedly arranged about the valve member 24, intermediate flanges or seats 36 and 38, is a suitably slotted and generally cylindrical ring-like member 44. The ring-like member 44 includes suitable sealant means 46 which may be disposed between the outer surface of member 44 and the inner surface of the filler tube 10 in such a manner that a sealing relationship is maintained therebetween. The ring-like member further includes a radial aperture or port 47 which opens to the unrestricted vent opening 18 provided in the filler tube 10. The ring-like member 44 also includes axially spaced flanges or seats 48, 50 and 51. As illustrated, flange or seat 48 is disposed on one side of opening 18 while flanges or seats 50, 51 are disposed on the opposite side of opening 18. A seal ring 52 may be disposed on one or both of the flanges 48 and 50. The spaced flanges or seats 48, 50, and 51 on the ring-like member selectively cooperate with the shoulders or flanges 36, 38, respectively, on the movable body 24 to define first and second annular sealant means.

The diameter of the bore or aperture 34 extending through the fuel tank nozzle receptacle assembly 24 is large enough to accommodate a fuel pump nozzle 54 during a fuel filling process. In this embodiment, bore 34 is provided with suitable sealant means 56. The sealant means 56 snugly fits about the pump nozzle inserted therethrough for preventing vapor escapement around the pump nozzle during the fuel filling process.

In the second embodiment of the invention illustrated in FIG. 2, those parts which serve substantially the same function or are similar to those in FIG. 1 are identified with like reference numerals. In this embodiment, operative means 58 are provided for preventing liquid fuel from entering vent port 18 and being delivered to the canister 20. Such operative means includes a housing and slideable valve combination. More specifically, a housing 60 including a vent port 18 leading to canister 20 is adapted to receive the vapors exiting aperture 47 on ring-like member 44. Interposed between aperture 47 and exit port 18 is a floating member which rises in response to liquid fuel levels. As will be readily understood, the floating member or valve 62 may be removed from the position shown in FIG. 2 in response to rising fuel levels and linearly moves such that it seats and seals against housing 60 to prevent the escapement of liquid fuel into the exit port 18. When the fuel level falls, the valve member 62 will respond accordingly.

For safety purposes, a pressure or safety release valve 64 may also be provided in combination with the valve assembly of the present invention. In its preferred form, the pressure relief valve 64 includes a resiliently biased member 66 adapted to normally close a fuel exit port 68 provided in the ring-like member 44.

A refueling vapor recovery system constructed in accordance with either embodiment will essentially operate in the following manner. As will be understood, the physical installation and removal of the sealant cap assembly 22 is the activator of the system. In a fuel refilling process, and upon removal of the closure member or cap 22, the internally threaded member or body 26, which is prevented from turning with the cap 22, will be automatically displaced endwise within the filler tube 10 to the limit of its travel. That is, threaded member 26 will be linearly displaced downward (as seen in the drawings) until shoulder 36 contacts the stationary upper seal face or seat 48 of the stationary ring-like member 44. In such position, the shoulder 36 and the seat 48 or sealant means 52 on the ring-like member cooperate to establish an annular sealant means disposed on one side of the vent port to prevent vapor escapement past movable body 26 to atmosphere. In the illustrated embodiment in FIG. 1, sealant member 52 also provides a seal between ring-like member 44 and inner surfaces of filler tube 10 preventing the escapement of fuel vapor therepast. Because of the linear displacement of member 26, a vapor flowpath is established between the lower seat or sealface 50 on the ring-like member and the other shoulder or flange 38 on the movable member 26. This flowpath permits communication between the interior 16 of the fuel tank and the vent port 18 leading to the canister 20. As such, vapor is free to flow through the valve area to the canister 20. Because a mechanical seal occurs on the outside diameter of the pump nozzle, vapor escapement may be controlled through the vent port 18 by the disposition of body member 26. Moreover, and because the valve assembly 24 is responsive to movement of the gas cap or sealant member 22, the opening of the vapor path to canister 20 is effected before or prior to the seal cap assembly 22 breaking the seal to atmosphere. By such construction, tank vapors may be "burped" prior to removing the gas cap thus avoiding the historic "hiss" or spit back of fuel.

As the fuel rises and covers the pump nozzle 54, a normal end-of-fill shut off should occur. Liquid could continue to be pumped if the automatic nozzle shut off fails. If the fuel rises sufficiently, the floating valve assembly 58 will be influenced by the rising fuel level. More specifically, if the fuel rises sufficiently, the floating member 62 will be linearly displaced into a sealing engagement with the housing 60 to prevent liquid fuel from being delivered into the vent port 18. Once the operative valve means 58 closes off the vent port 18 and if fuel is continually pumped into the tank 12 a pressure rise in the tank will result. When the pressure rise exceeds the predetermined value set by the check valve 64, the valve 64 will open. Thus, liquid will be released to atmosphere at the filler neck location which will alert the customer to a nozzle malfunction and prompt a manual shut off.

The removal of the pump nozzle after filling and the reinstallation of the closure assembly 22 affects linear displacement of the operative assembly 24 and seals the vent port 18 and canister 20 from communication with the fuel tank interior 16. That is, the combined interengagement of the threaded elements on gas cap assembly 22 and member 26 will, understandably, cause linear displacement of body member against the action of the resilient means 42. Such displacement causes shoulder or seat 38 on valve member 26 to sealingly engage with seats or flanges 50 and 51 on the annular ring-like member 44. Because the second annular seal is disposed on the opposite side of the vent port, a second annular seal is established therebetween. As such, the vent 18 and canister 20 are closed or sealed off from communication with the interior 16 of the gas tank.

The design of this system is such that all the valving mechanisms are in-board of the fill neck housing. This results in an impact resistant design whose integrity is maintained as long as the gas cap assembly remains in position. Even in the event of the operative valve means 58 being sheared off, the fuel tank environment remains sealed to atmosphere by the operative valve arrangement 24. The net result is a system that is mechanical in nature which minimizes changes to the vehicle, provides minimal changes to the customer's refueling sequence, and maximizes integrity under potential collision situations.

Thus, there has been provided a VEHICLE FUEL TANK VAPOR RECOVERY SYSTEM which fully satisfies the aims, objectives, and advantages set forth above. While the invention has been described in connection with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.