Closure assembly for a tank filler neck

Abstract

A filler neck closure assembly for a vehicle fuel tank filler neck, comprising: a housing configured to be mounted in the filler neck and formed to include a sealing surface and a pressure-relief valve positioned to lie in the housing and provided with a nozzle-receiving portion and a sealing portion, wherein the nozzle-receiving portion is formed to include a nozzle-receiving opening sized to receive a pump nozzle during refueling of the fuel tank and the sealing portion is movable with the nozzle portion and relative to the housing between a closure-sealing position sealingly engaging the sealing surface and a pressure-relief position away from the sealing surface to define an opening to vent fuel vapor from the fuel tank when tank pressure exceeds a predetermined maximum pressure. The housing is formed to include a passageway containing the pressure-relief valve therein and defines an annular space around the pressure-relief valve, between the pressure-relief valve and the housing, and with a coiled compression spring positioned in the annular space, the pressure-relief valve including an axially outwardly extending annular guide wall adjacent to the annular space which defines a radially inner side of the annular space, the housing further including a radially inwardly extending annular lip wherein the guide wall slidingly engages the lip of the housing to radially guide the pressure-relief valve during movement of the pressure-relief valve between the closure-sealing position and the pressure-relief position.

I claim:  
     
       1. A filler neck closure assembly for a vehicle fuel tank filler neck, the assembly comprising 
       a closure for closing the filler neck, the closure including a housing formed to include an interior region for receiving fuel vapor in the filler neck and a vent aperture for discharging fuel vapor from the interior region, closure retainer apparatus appended to the housing and configured to engage the filler neck when the housing is installed in the filler neck to block removal of the closure from the filler neck, a seal member engaging the housing and lying in a position to engage the filler neck to establish a sealed connection between the housing and the filler neck when the housing is installed in the filler neck, and a movable tank pressure control assembly mounted for movement in the interior region of the housing between a filler neck-closing position blocking discharge of fuel vapor in the filler neck through the vent aperture and a filler neck-venting position allowing discharge of fuel vapor in the filler neck through the vent aperture, the movable tank pressure control assembly including a nozzle-receiving opening and a door mechanism normally closing the nozzle-receiving opening.  
     
     
       2. The assembly of  claim 1 , further comprising an outer shell formed to include a nozzle-receiving opening aligned with the nozzle-receiving opening formed in the movable tank pressure control assembly to allow a fuel pump nozzle to pass through said nozzle-receiving opening and open the door mechanism to reach the interior region of the housing, the outer shell being mounted on the housing for rotation about an axis passing through the interior region of the housing to allow the outer shell to be rotated relative to the housing to a predetermined orientation relative to the housing. 
     
     
       3. The assembly of  claim 2 , wherein the closure retainer apparatus includes annular flanges for rotatably engaging the filler neck and further comprising a torque-override mechanism engaging the outer shell and housing and providing a torque-limited driving connection between the outer shell and the housing when the outer shell is rotated in a cap-advancing direction. 
     
     
       4. The assembly of  claim 2 , wherein the torque-override mechanism includes a resilient finger cantilevered to the housing, a driven tooth appended to the resilient finger to move therewith relative to the housing, and a plurality of drive teeth appended to the outer shell and positioned to engage the driven tooth on the resilient finger in response to rotation of the outer shell about the axis of rotation. 
     
     
       5. The assembly of  claim 4 , wherein the housing includes a body engaging the seal member and a frangible section interconnecting the body and the resilient finger to support the resilient finger in a cantilevered position relative to the housing. 
     
     
       6. The assembly of  claim 3 , wherein the torque-override mechanism includes a plurality of resilient fingers cantilevered to the housing, a driven tooth appended to each resilient finger, and a plurality of drive teeth appended to the outer shall and positioned to engage the driven teeth on the resilient fingers in response to rotation of the outer shell about the axis of rotation. 
     
     
       7. The assembly of  claim 6 , wherein the housing includes a body engaging the seal member and a frangible section interconnecting the body and each of the resilient fingers to support the resilient fingers in cantilevered positions relative to the housing. 
     
     
       8. The assembly of  claim 3 , wherein the housing includes an outer body termed  formed to include the vent aperture and the torque-override mechanism includes a resilient finger cantilevered to the outer body, a driven tooth appended to the resilient finger, and a plurality of drive teeth appended to the outer shell and positioned to engage the driven tooth on the resilient arm in response to rotation of the outer shell about the axis of rotation. 
     
     
       9. The assembly of  claim 2 , wherein the outer shell includes a side wall having an annular outer edge and a front wall appended to the annular outer edge and formed to include the nozzle-receiving opening formed in the outer shell, the side wall and the front wall cooperate to define an enclosed space receiving an axially outer portion of the housing therein. 
     
     
       10. The assembly of  claim 9 , wherein the front wall includes a nozzle-guiding surface inclined with respect to the axis of rotation and positioned to lie between the annular outer edge of the side wall and the nozzle-receiving opening formed in the outer shell. 
     
     
       11. The assembly of  claim 9 , wherein the outer shell further includes a plurality of drive teeth positioned to lie in the enclosed space and engage the housing to provide a rotational driving connection between the outer shell and the housing. 
     
     
       12. The assembly of  claim 9 , further comprising a torque-override mechanism engaging the outer shell and housing in the enclosed space and providing a torque-limited driving connection between the-outer  the outer shell and the housing. 
     
     
       13. The assembly of  claim 9 , wherein the side wall includes an annular interior surface and the housing includes an annular flange lying in the enclosed space and having an annular outer edge abutting the annular interior surface of the side wall in rotative bearing engagement. 
     
     
       14. The assembly of  claim 13 , wherein the housing includes a body engaging the seal member and a frangible section interconnecting the body and the annular flange. 
     
     
       15. The assembly of  claim 13 , wherein the housing includes a body formed to include the interior region and the annular flange includes an inner edge appended to the body. 
     
     
       16. The assembly of  claim 13 , wherein the housing includes a body formed to include the interior region and the annular flange is coupled to the body, and further comprising a torque-override mechanism lying in the enclosed space and including a resilient finger cantilevered to the annular flange, a driven tooth appended to the resilient finger to move therewith in the enclosed space relative to the annular flange, and a plurality of drive teeth appended to the outer shell to lie in the enclosed space and engage the driven tooth on the resilient finger in response to rotation of the outer shell relative to the housing about the axis of rotation. 
     
     
       17. The assembly of  claim 16 , wherein the housing further includes a frangible section appended to the body and the annular flange is coupled to the body by the frangible section. 
     
     
       18. The assembly of  claim 13 , wherein the housing is formed to position the vent aperture to pen into the enclosed space in close proximity to the annular flange. 
     
     
       19. The assembly of  claim 2 , wherein the outer shell is formed to include a spline-receiving space and the movable tank pressure control assembly is formed to include a spline received in the spline-receiving space formed in the outer shell so that the movable tank pressure control assembly is keyed to rotate with the outer shell relative to the housing in response to rotation of the outer shell about the axis of rotation. 
     
     
       20. The assembly of  claim 19 , wherein the outer shell includes a side wall having an annular outer edge and a front wall appended to the annular outer edge and formed to include the nozzle-receiving opening formed in the outer shell, the side wall and the front wall cooperate to define an enclosed space receiving an axially outer portion of the housing therein, and the outer shell further includes lugs positioned to lie in the enclosed space to define the spline-receiving space therebetween. 
     
     
       21. The assembly of  claim 19 , wherein the movable tank pressure control assembly includes a pressure-relief seal plate having an annular lip and an annular guide wall appended to the annular lip, a spring lying around the annular guide wall and yieldably biasing the annular lip to urge the annular lip to a normally closed position engaging the housing to establish the filler neck-closing position of the movable tank pressure control assembly, and the spline is appended to the annular guide wall. 
     
     
       22. The assembly of  claim 19 , whereto  wherein the outer shell includes a side wall and a front wall appended to the side wall, the front wall is formed to include the nozzle-receiving opening formed in the outer shell, an interior surface facing toward the movable tank pressure control assembly, an exterior surface defining a nozzle-guiding surface terminating at the nozzle-receiving opening, and a lug appended to the interior surface to define an outer boundary of the spline-receiving space and positioned to engage the spline included in the movable tank pressure control assembly during rotation of the outer shell relative to the housing about the axis of rotation. 
     
     
       23. The assembly of  claim 1 , wherein the housing includes an inner body carrying the closure retainer apparatus and an outer body coupled to the inner body to define the interior region therebetween and formed to include the vent aperture and an outer opening receiving the movable tank pressure control assembly to permit insertion of a fuel-dispensing nozzle into the interior region of the housing through the nozzle-receiving opening. 
     
     
       24. The assembly of  claim 23 , wherein the inner body includes a cylindrical sleeve having an outer end adjacent to the movable tank pressure control assembly, an opposite inner end, and an exterior surface extending between the inner and outer ends, the closure retainer apparatus includes an annular flange appended to the exterior surface and configured to rotatably engage the filler neck, the inner body further includes a radially outwardly extending annular lip appended to the outer end of the cylindrical sleeve and having an axially inner surface facing in a first direction toward the annular flange and an axially outer surface facing in an opposite second direction, and the seal member lies around the cylindrical sleeve to abut the axially inner surface of the radially outwardly extending annular lip and the exterior surface of the cylindrical sleeve in a position lying between the annular flange and the annular lip. 
     
     
       25. The assembly of  claim 24 , wherein the movable tank pressure control assembly includes an annular seal abutting the axial outer surface of the annular lip, a pressure-relief seal plate formed to include the nozzle-receiving opening, and a spring yieldably biasing the pressure-relief seal plate to a normally closed position engaging the annular seal to block discharge of fuel vapor in the inner body through the vent aperture. 
     
     
       26. The assembly of  claim 23 , further comprising an outer shell formed to include an interior region receiving a portion of the outer body and a nozzle-receiving opening communicating with the nozzle-receiving opening formed in the movable tank pressure control assembly, the outer shell being mounted on the outer body for rotation relative to the outer body about an axis of rotation, and a torque-override mechanism engaging the outer shell and outer body and providing a torque-limited driving connection between the outer shell and outer body when the outer shell is rotated about the axis of rotation in a cap-advancing direction. 
     
     
       27. The assembly of  claim 26 , wherein the outer shell is formed to include a spline-receiving space and the movable tank pressure control assembly is formed to include a spline received in the spline-receiving space formed in the outer shell so that the movable tank pressure control assembly is keyed to rotate with the outer shell relative to the housing in response to rotation of the outer shell about the axis of rotation. 
     
     
       28. The assembly of  claim 1 , wherein the movable tank pressure control assembly includes a pressure-relief seal plate formed to include the nozzle-receiving opening formed in the movable tank pressure control assembly and a spring engaging the housing and the pressure-relief seal plate to yieldably urge the pressure-relief seal plate to a normally closed position against the housing to establish the filler neck-closing position of the movable tank pressure control assembly. 
     
     
       29. The assembly of  claim 28 , wherein the door mechanism includes a vacuum-relief valve coupled to the pressure-relief seal plate for movement between a closed position closing the nozzle-receiving opening and an open position opening the nozzle-receiving opening and a spring yieldably biasing the vacuum-relief valve to the closed position. 
     
     
       30. The assembly of  claim 28 , wherein the housing includes an exterior surface abutting the seal member and an interior surface lying in the interior region, the movable tank pressure control assembly further includes an annular seal engaging the interior surface, and the spring is configured to yieldably urge the pressure-relief seal plate against the annular seal to establish the filler neck-closing position and partition the interior region into an inner chamber positioned to communicate with the filler neck and an outer chamber communicating with the vent aperture formed in the housing. 
     
     
       31. The assembly of  claim 30 , wherein the spring is positioned to lie in the outer chamber. 
     
     
       32. The assembly of  claim 28 , further comprising an outer shell formed to include an interior region receiving a portion of the housing and a nozzle-receiving opening communicating with the nozzle-receiving opening formed in the pressure-relief seal plate, the outer shell being mounted on the housing for rotation relative to the housing about an axis of rotation, the outer shell being formed to include a spline-receiving space, and the pressure-relief seal plate including a spline received in the spline-receiving space formed in the outer shell so that the pressure-relief seal plate is keyed to rotate with the outer shell relative to the housing in response to rotation of the outer shell about the axis of rotation. 
     
     
       33. A filler neck closure assembly for a vehicle fuel tank filler neck, the assembly comprising 
       a housing configured to mount in the filler neck and formed to include a sealing surface, and  
       a pressure-relief valve positioned to lie in the housing, the pressure-relief valve including a nozzle-receiving portion and a sealing portion, the nozzle-receiving portion being formed to include a nozzle-receiving opening sized to receive a pump nozzle during refueling of the fuel tank the sealing portion being movable relative to the housing between a closure-sealing position sealingly engaging the sealing surface and a pressure-relief position away from the sealing surface to define an opening therebetween to vent fuel vapor from the fuel tank when tank pressure exceeds a predetermined maximum pressure, the nozzle-receiving portion moving axially with the sealing portion during movement of the sealing portion between the closure-sealing position and the pressure-relief position, and wherein the housing is formed to include a passageway extending therethrough and containing the pressure-relief valve therein, the housing and the pressure-relief valve cooperate to define an annular space around the pressure-relief valve and between the pressure-relief valve and the housing, and a coiled compression spring is positioned in the annular space, the pressure-relief valve includes an axially outwardly extending annular guide wall adjacent to the annular space and the guide wall defines a radially inner side of the annular space, the housing further includes a radially inwardly extending annular lip appended to the housing and the guide wall slidingly engages the lip of the housing to radially guide the pressure-relief valve during movement of the pressure-relief valve between the closure-sealing position and the pressure-relief position.  
     
     
       34. A filler neck closure assembly for a vehicle fuel tank filler neck, the assembly comprising 
       a housing configured to mount in the filler neck and formed to include a sealing surface,  
       a pressure-relief valve positioned to lie in the housing, the pressure-relief valve including a nozzle-receiving portion and a sealing portion, the nozzle-receiving portion being formed to include a nozzle-receiving opening sized to receive a pump nozzle during refueling of the fuel tank, the sealing portion being movable relative to the housing between a closure-sealing position sealingly engaging the sealing surface and a pressure-relief position away from the sealing surface to define an opening therebetween to vent fuel vapor from the fuel tank when the tank pressure exceeds a predetermined maximum pressure, the nozzle-receiving portion moving axially with the sealing portion during movement of the sealing portion between the closure-sealing position and the pressure-relief position, the housing being formed to include a passageway extending therethrough and containing the pressure-relief valve therein, the pressure-relief valve including an axially outwardly extending annular guide wall, the housing and the pressure-relief valve cooperating to define an annular space around the annular guide wall of the pressure-relief valve and between the annular guide wall and the housing the annular guide wall being adjacent to the annular space to dating  define a radially inner side of the annular space,  
       a coiled compression spring positioned to lie in the annular space and surround the annular guide wall between the sealing portion of the pressure-relief valve and the annular lip of the housing, and  
       an outer shell rotatably connected to the housing, the outer shall  shell including a plurality of axially inwardly directed drive teeth, the housing further including a plurality of driven teeth and means for biasing the driven teeth axially outwardly, the driven teeth being configured to engage the drive teeth to provide a torque-limited connection between the outer shell and the housing when the outer shell is rotated in a closure-advancing direction.  
     
     
       35. The assembly of  claim 34 , wherein the drive teeth on the outer shell are positioned to lie radially outwardly of the coiled compression spring. 
     
     
       36. A filler neck closure assembly for a vehicle fuel tank filler neck, the assembly comprising 
       a housing configured to mount in the filler neck and formed to include a sealing surface, and  
       a pressure-relief valve positioned to lie in the housing, the pressure-relief valve including a nozzle-receiving portion and a sealing portion, the nozzle-receiving portion being formed to include a nozzle-receiving opening sized to receive a pump nozzle during refueling of the fuel tank, the sealing portion being movable relative to the housing between a closure-sealing position sealingly engaging the sealing surface and a pressure-relief position away from the sealing surface to define an opening therebetween to vent fuel vapor from the fuel tank when tank pressure exceeds a predetermined maximum pressure, the nozzle-receiving portion moving axially with the sealing portion during movement of the sealing portion between the closure-sealing position and the pressure-relief position, wherein the housing is formed to include a radially inwardly extending lip appended to an axially outer portion of the housing, the filler neck closure further comprises a spring engaging the lip of the housing mad  and the pressure-relief valve to yieldably bias the pressure-relief valve toward the closure-sealing position, an outer shell adjacent to an axial outer end of the housing, and a radially outwardly extending flange appended to the housing and interconnecting the outer shell and the housing, the flange including a frangible section configured to fracture in response to an impact to the outer shell leaving the housing intact to seal the filler neck, the flange being appended to the housing axially adjacent to the lip.  
     
     
       37. The assembly of  claim 36 , wherein the lip is integrally appended to an axially upper edge of the housing, the flange is formed to include a groove to define the frangible portion of the flange, and the groove is formed to lie adjacent to the radially outer edge of the lip. 
     
     
       38. A filler neck closure assembly for a vehicle fuel tank filler neck, the assembly comprising 
       a housing configured to mount in the filler neck, the housing being formed to include an interior region having an outlet in fluid communication with the filler neck and a vent aperture for discharging fuel vapor extant in the interior region from the housing,  
       an outer shell rotatably coupled to the housing,  
       a pressure-relief valve movable relative to the housing between a closed position partitioning the interior region to define an inner chamber communicating with the outlet and an outer chamber communicating with the vent aperture and blocking the flow of fuel vapor from the inner chamber to the outer chamber and a pressure-relief position allowing the flow of fuel vapor from the inner chamber to the outer chamber to vent fuel vapor from the fuel tank through the interior region of the housing and the vent aperture formed in the housing when tank pressure exceeds a predetermined maximum pressure, and  
       a spline interposed between the outer shell and the housing, the spline imparting rotational movement from the outer shell to the pressure-relief valve to rotate the pressure-relief valve relative to the housing in response to rotational movement of the outer shell relative to the housing, the spline blocking independent rotational movement of the outer shell relative to the pressure-relief valve.  
     
     
       39. The assembly of  claim 38 , wherein the outer shell is formed to include a spline-receiving space and the spline is appended to the pressure-relief valve and the spline is received in the spline-receiving space. 
     
     
       40. The assembly of  claim 38 , wherein the outer shell includes an axis of rotation and a front wall formed to include an outer opening sized to receive a pump nozzle during refueling of the fuel tank, the outer opening includes a first central axis coincident with the axis of rotation of the outer shell, and the pressure-relief valve is formed to include an inner opening sized to receive a pump nozzle during refueling of the fuel tank, the inner opening having a second central axis spaced apart from the first central axis. 
     
     
       41. The assembly of  claim 40 , further comprising a base positioned to lie between the filler neck and the housing, the base including an axially inner wall formed to include an unleaded discriminator opening sized to receive a pump nozzle during refueling of the fuel tank, the outer opening, the inner opening, and the unleaded discriminator opening each being positioned to receive the pump nozzle during refueling of the fuel tank. 
     
     
       42. The assembly of  claim 38 , further comprising a circular plate pivotably appended to the pressure-relief valve and movable between a closed position engaging the pressure-relief valve and a fully open position away from the pressure-relief valve, the pressure-relief valve being formed to include a nozzle-receiving opening sized to receive a pump nozzle, during refueling of the fuel tank, the circular plate covering the nozzle-receiving opening when the circular plate is in the closed position and engaging the pump nozzle when in the fully open position during refueling of the fuel tank. 
     
     
       43. The assembly of  claim 42 , further comprising a spring mounted in the housing and engaging the circular plate to yieldably bias the circular plate toward the closed position, the spring acting through the circular plate to yieldably bias the pump nozzle radially outwardly during refueling of the fuel tank. 
     
     
       44. A filler neck closure assembly for a vehicle fuel tank filler neck, the assembly comprising 
       a housing configured to mount in the filler neck and formed to include an interior region and a sealing surface,  
       a pressure-relief valve positioned to lie in the interior region of the housing, the pressure-relief valve being movable relative to the housing between a closure-sealing position sealingly engaging the sealing surface and a pressure-relief position away from the sealing surface to define an opening therebetween to vent fuel vapor from the fuel tank when tank pressure exceeds a predetermined maximum pressure, and  
       an outer shell mounted on the housing for rotation about an axis passing through the interior region formed in the housing, the outer shell including a side wall and a front wall cooperating with the side wall to define an enclosed space receiving an axially outer portion of the pressure-relief valve when the pressure-relief valve is in the pressure-relief position.  
     
     
       45. The assembly of  claim 44 , wherein the front wall is further formed to include axially inwardly cantilevered drive teeth positioned to lie in the enclosed space of the outer shell and engaging the housing to provide a rotational driving connection between the outer shell and the housing. 
     
     
       46. The assembly of  claim 44 , wherein the front wall is further formed to include a funnel-shaped nozzle-guiding surface to guide the radial movement of the pump nozzle toward the nozzle-receiving opening as the pump nozzle advances axially toward the nozzle-receiving opening during refueling of the fuel tank. 
     
     
       47. The assembly of  claim 44 , further comprising a torque-override mechanism for providing a torque-limited connection between the outer shell and the housing so that the outer shell rotates independently of the housing upon the application of torque above a predetermined maximum torque on the outer shell, the torque-override mechanism being appended to the outer shell and the housing and positioned to lie in the enclosed space defined by the side wall and front wall of the outer shell. 
     
     
       48. The assembly of  claim 44 , wherein the pressure-relief valve is formed to include a spline, the outer shell is rotatably coupled to the housing and is formed to include a spline-receiving space, and the spline is received in the spline-receiving space so that the pressure-relief valve rotates with the outer shell relative to the housing when the outer shell rotates relative to the housing. 
     
     
       49. The assembly of  claim 48 , further comprising a flapper door and a spring engaging the flapper door to yieldably bias the flapper door against the nozzle-receiving portion to cover the nozzle-receiving opening, the flapper door being pivotably connected to the pressure-relief valve and arranged to rotate relative to the housing with the pressure-relief valve when the pressure-relief valve rotates relative to the housing in response to rotation of the outer shell relative to the housing. 
     
     
       50. The assembly of  claim 44 , further comprising a base interposed between the filler neck and the housing and a sealing gasket interposed between the base and the housing and sealingly engaging the base and the housing to block the flow of liquid fuel, fuel vapor, and air therebetween. 
     
     
       51. The assembly of  claim 50 , wherein the housing is formed to include an inner body received by the base and an outer body connected to the inner body and the outer shell is connected to the outer body. 
     
     
       52. The assembly of  claim 51 , wherein the outer body is formed to include an interior region, the inner body is formed to include an interior region in fluid communication with the interior region of the outer body, and the pressure-relief valve is received in the interior region of the outer body. 
     
     
       53. The assembly of  claim 51 , further comprising an o-ring seal mounted on the sealing surface to provide a seal between the pressure-relief valve and the inner body of the housing thereby blocking the flow of liquid fuel, fuel vapor, and air therebetween when the pressure-relief valve is in the closure-sealing position, the inner body of the housing being formed to include a radially outwardly extending annular lip having an axially outwardly facing surface including the sealing surface and engaging the o-ring seal and an axially inwardly-facing surface engaging the sealing gasket. 
     
     
       54. The assembly of  claim 44 , wherein the side wall is formed to include an axially inner edge lying in a first plane and an axially outer edge lying in a second plane that is inclined relative to the first plane. 
     
     
       55. The assembly of  claim 54 , wherein the front wall is formed to include a nozzle-receiving opening sized to receive a pump nozzle during refueling of the fuel tank and a funnel-shaped nozzle-guiding surface to guide the radial movement of the pump nozzle toward the nozzle-receiving opening as the pump nozzle advances axially toward the nozzle-receiving opening during refueling of the fuel tank. 
     
     
       56. A filler neck closure assembly for a vehicle fuel tank filler neck, the filler neck closure assembly comprising 
       a housing configured to mount in the filler neck,  
       a closure portion mounted in the housing and having an aperture for receiving a nozzle to introduce fuel into the filler neck,  
       a plate,  
       means for supporting the plate for movement relative to the closure portion between a closed position blocking the flow of air through the aperture means and an open position allowing the flow of air through the aperture means when the tank pressure is less than a predetermined minimum pressure, the supporting means being appended to the closure portion,  
       a spring lying in the housing and yieldably biasing the plate against the closure portion, the spring having a spring constant such that the plate sealingly engages the closure portion when the tank pressure is above the predetermined minimum pressure and such that the plate disengages from the closure portion when tank pressure is below the predetermined minimum pressure to form an opening therebetween allowing the flow of air through the aperture means, through the opening, and into the fuel tank, the closure portion being formed to include a spline, and  
       an outer shell rotatably connected to the housing and formed to include a spline-receiving space positioned to receive the spline so that the closure portion rotates relative to the housing with the outer shell as the outer shell rotates relative to the housing.  
     
     
       57. A filler neck closure assembly for a vehicle fuel tank filler neck, the filler neck closure assembly comprising 
       a housing configured to mount in the filler neck,  
       a closure portion mounted in the housing and having aperture means for receiving a nozzle to introduce fuel into the filler neck,  
       a plate,  
       means for supporting the plate for movement relative to the closure portion between a closed position blocking the flow of air through the aperture means and an open position allowing the flow of air through the aperture means when the tank pressure is less than a predetermined minimum pressure, the supporting means being appended to the closure portion,  
       a spring lying in the housing and yieldably biasing the plate against the closure portion, the spring having a spring constant such that the plate sealingly engages the closure portion when the tank pressure is above the predetermined minimum pressure and such that the plate disengages from the closure portion when tank pressure is blow the predetermined minimum pressure to form an opening therebetween allowing the flow of air through the aperture Weans, through the opening, and into the fuel tank, the closure portion being mounted for movement relative to the housing between a closed position blocking the flow of fuel vapor between the housing and the closure portion and an open position allowing the flow of fuel vapor between the closure portion and the housing when the tank pressure is above a predetermined maximum pressure, and  
       a compression spring yieldably biasing the closure portion toward the closed position, the compression spring having a first end engaging the closure portion, a second end engaging the housing, and the compression spring being positioned to lie axially outward of the spring yieldably biasing the plate against the closure portion.  
     
     
       58. A filler neck closure assembly for a vehicle fuel tank filler neck, the assembly comprising 
       a housing configured to be received by the filler neck,  
       a sealing gasket positioned to lie between the housing and the filler neck, the sealing gasket being subject to damage due to overtightening of the closure assembly on the filler neck,  
       an outer shell rotatably connected to the housing, the outer shell being formed to include a nozzle-receiving opening, and  
       a torque-override mechanism for providing a torque-limited connection between the outer shell and the housing to protect the gasket from over tightening of the closure assembly on the filler neck resulting from the application of torque above a predetermined maximum torque on the outer shell, the torque-override mechanism including drive teeth appended to the outer shell.  
     
     
       59. The assembly of  claim 58 , further comprising a base disposed in the filler neck between the filler neck and the housing, the base being formed to include a mouth having a lip arranged to engage the sealing gasket and an axially inner wall having an unleaded discriminator. 
     
     
       60. The assembly of  claim 58 , wherein the torque-override mechanism further includes a flange appended to the housing, the flange having a plurality of driven teeth and a spring for yieldably biasing the driven teeth axially outwardly, and the driven teeth are configured to engage the drive teeth. 
     
     
       61. The assembly of  claim 60 , wherein the spring includes resilient fingers connected to the flange and cantilevered therefrom and the driven teeth are appended to the resilient fingers. 
     
     
       62. The assembly of  claim 58 , wherein the drive teeth are spaced apart along a generally circular path that is positioned to lie radially outwardly of the sealing gasket. 
     
     
       63. The assembly of  claim 58 , wherein the outer shell is formed to include a front wall arranged to define a generally funnel-shaped nozzle-guiding surface terminating at the nozzle-receiving opening. 
     
     
       64. The assembly of  claim 63 , further comprising a latching portion integrally appended to the front wall and positioned to engage the pump nozzle during refueling of the fuel tank to prevent inadvertent axial movement of the pump nozzle out of the nozzle-receiving opening. 
     
     
       65. The assembly of  claim 58 , wherein the outer shell is formed to include a front wall arranged to define a generally planar boot-seating surface adjacent to the nozzle-receiving opening. 
     
     
       66. A self- closing cap adapted to be mounted onto a filler neck of a fuel tank of an automotive vehicle wherein said neck includes a restrictive flap pivotally connected thereto, comprising:   
       a closure ring having an annular body and means for detachably mounting the periphery of said annular body around a peripheral edge of a filler neck, 
       a closure flap assembly including a circular member having an opening for receiving a nozzle, a closure flap, means for pivotally mounting an edge of said closure flap over said opening, and means for affixing said circular member to said annular body such that the orientation of said pivotal mounting means is adjustable relative to a pivotal connection between said restrictive flap and said neck, and 
       a cover means detachably mountable over said closure flap assembly. 
     
     
       67. The self- closing cap as defined in    claim 66   , wherein said closure flap is spring biased over said opening in said circular member.   
     
     
       68. The self- closing cap as defined in    claim 66   , wherein said means for affixing said circular member to said annular body includes a ratchet lock mechanism.   
     
     
       69. The self- closing cap as defined in    claim 66   , wherein said cover means includes a port for receiving a nozzle and a guide face for guiding said nozzle into said port.   
     
     
       70. The self- closing cap as defined in    claim 69   , wherein said guide face is inclined with respect to said circular member of said closure flap assembly to facilitate the guiding of said nozzle into said port.   
     
     
       71. The self- closing cap as defined in    claim 70   , wherein said filler neck is inclined at an oblique angle with respect to an adjacent wall of said vehicle, and said inclination of said guide face orients said face at an angle that facilitates the insertion of a fuel nozzle from an automatic filling machine.   
     
     
       72. The self- closing cap as defined in    claim 69   , wherein said cover means includes means for guiding the nozzle of an automatic fuel - dispensing machine.   
     
     
       73. A self- closing cap for attachment to the fuel filler neck of a vehicle that is particularly adapted for use with an automatic filling machine, said neck having a restrictive flap within its inner diameter that is connected thereto by a pivotal connection, comprising:   
       a closure ring having an annular body and means for detachably mounting the periphery of said annular body around the periphery of a filler neck, 
       a closure flap assembly including a circular member having an opening, a closure flap, means for pivotally mounting said closure flap over said opening, and means for affixing said circular member at a selected position with respect to the periphery of said annular body of said closure ring after said ring has been mounted around the periphery of said filler neck such that the orientation of said pivotal mounting means is angularly adjustable relative to said annular body to a position substantially 180° opposite from said pivotal connection of said restrictive flap, and 
       a cover means detachably mountable over said closure flap assembly. 
     
     
       74. The self- closing cap as defined in    claim 73   , wherein both said restrictive flap and said closure flap are spring biased over said neck inner diameter and opening, respectively, and wherein said  180 ° orientation between said pivotal connection and said pivotal mounting means facilitates the insertion and withdrawal of a fuel dispensing nozzle from an automatic filling machine through said cap and filler neck.   
     
     
       75. The self- closing cap as defined in    claim 73   , wherein said affixing means includes a ratchet lock mechanism.   
     
     
       76. The self- closing cap as defined in    claim 73   , wherein said cover means includes a port for receiving a fuel nozzle, and a guide face for guiding said nozzle into said port.   
     
     
       77. The self- closing cap as defined in    claim 76   , wherein said guide face is inclined with respect to said circular member of said closure flap assembly to facilitate the guiding of said fuel nozzle into said port.   
     
     
       78. The self- closing cap as defined in    claim 77   , wherein said filler neck is inclined at an oblique angle with respect to an adjacent wall of said vehicle, and said inclination of said guide face facilitates the insertion of said fuel nozzle into said port and through said opening.   
     
     
       79. The self- closing cap as defined in    claim 77   , wherein said cover means includes means for guiding the nozzle of an automatic fuel dispensing machine.   
     
     
       80. A self- closing cap adapted to be mounted onto a filler neck of a fuel tank of an automotive vehicle, comprising:   
       a closure ring having an annular body and means for detachably mounting the periphery of said annular body around a peripheral edge of a filler neck, and 
       a closure flap assembly including a circular member having an opening for receiving a nozzle, a closure flap, means for pivotally mounting an edge of said closure flap over said opening, and means for permanently affixing said circular member to said annular body such that the orientation of said pivotal mounting means is angularly adjustable relative to said annular body, and 
       a cover means detachably mountable over said closure flap assembly.