Fuel tank venting system

Claim 2

A fuel tank venting system comprising: a fuel tank having a vapor space and a filler pipe with an open end, cap means removably connected to the open end of said pipe, means defining a restricted vapor path from said tank, a vent pipe connected to said restricted path including a first open end adapted to be connected to a charcoal canister for absorbing fuel vapors and a second open end, means defining a refueling vent opening within said filler pipe connected to said second open end and having less restriction than said first vapor path for unrestricted flow of vapor from said tank and said filler pipe during a closed fuel fill phase of operation to reduce fill pressure build-up, and seal means operative when said cap means is in place on said filler pipe to block communication between said tank and said refueling vent opening so as to direct vapor flow from said tank through said restricted vapor path during vehicle operation.

Claim 3

A fuel tank vent system comprising: a Fuel tank having a vapor space and a fuel filler pipe, means including a restricted orifice from said tank and a vent pipe adapted to be connected to a carbon canister for absorbing vapors from the tank, an unrestricted opening in said filler pipe for directing vapor from said tank during a closed fuel filling phase of operation, a fuel cap on said pipe for closing said pipe after fill, means within said filler pipe for sealing against said fuel cap thereon to effect a secondary seal between said tank and said unrestricted filler pipe vapor opening whereby vapor flow is directed only through said orifice when the cap is in place, and means for removing said secondary seal means during the closed fill phase of operation to allow vapor flow from said tank to pass through said unrestricted filler neck opening, and means for connecting said filler pipe vapor opening to said vent pipe whereby fuel vapors are directed to the charcoal canister from the tank during the closed fuel fill phase of operation without undesirable increase in tank pressure.

Claim 4

A fuel tank vent system comprising: a Fuel tank having a vapor space and a fuel filler pipe, means including a restricted orifice from said tank and a vent pipe adapted to be connected to a carbon canister for absorbing vapors from the tank, an unrestricted opening in said filler pipe for directing vapor from said tank during a closed fuel filling phase of operation, a fuel cap on said pipe for closing said pipe after fill, means within said filler pipe for sealing against said fuel cap thereon to effect a secondary seal between said tank and said unrestricted filler pipe vapor opening whereby vapor flow is directed only through said orifice when the cap is in place, and means for removing said secondary seal means during the closed fill phase of operation to allow vapor flow from said tank to pass through said unrestricted filler neck opening, and means for connecting said filler pipe vapor opening to said vent pipe whereby fuel vapors are directed to the charcoal canister from the tank during the closed fuel fill phase of operation without undesirable increase in tank pressure.

Claim 5

In a fuel system comprising a tank having a vapor space and a fuel filler pipe with an open end, the improvement comprising: a first vapor vent pipe connected to said tank having opposite opened ends thereon, a second vent pipe on said filler pipe adjacent the open end thereon, means defining a restricted vapor path from the vapor space of said tank into said first vent pipe, means defining an unrestricted vapor opening in said filler pipe in communication with said second vent pipe, seal means within said filler pipe located between said tank and the unrestricted opening in said filler pipe, cap means adapted to be removably secured to the open end of said filler pipe including means thereon coacting with said seal means to define a secondary cap seal between said tank and said unrestricted opening when the cap is in place whereby vapor flow is through said restricted flow path to a carbon canister for absorbing vapors from said tank during vehicle operation, means defining a primary cap seal between said cap and said filler pipe to seal the unrestricted opening during vehicle operation, said primary and secondary cap seals being removably during a closed fill phase of operation so that vapors are directed from the vapor space tank upwardly through the filler pipe to pass through said unrestricted opening thence through said second vent pipe and said first vent pipe to said carbon canister whereby refueling can proceed with little or no pressure buildup in said fuel tank.

Claim 6

In a fuel system comprising a tank having a vapor space and a fuel filler pipe with an open end, the improvement comprising: a first vapor vent pipe connected to said tank having opposite opened ends thereon, a second vent pipe on said filler pipe adjacent the open end thereon, means defining a restricted vapor path from the vapor space of said tank into said first vent pipe, means defining an unrestricted vapor opening in said filler pipe in communication with said second vent pipe, seal means within said filler pipe located between said tank and the unrestricted opening in said filler pipe, cap means adapted to be removably secured to the open end of said filler pipe including means thereon coacting with said seal means to define a secondary cap seal between said tank and said unrestricted opening when the cap is in place whereby vapor flow is through said restricted flow path to a carbon canister for absorbing vapors from said tank during vehicle operation, means defining a primary cap seal between said cap and said filler pipe to seal the unrestricted opening during vehicle operation, said primary and secondary cap seals being removably during a closed fill phase of operation so that vapors are directed from the vapor space tank upwardly through the filler pipe to pass through said unrestricted opening thence through said second vent pipe and said first vent pipe to said carbon canister whereby refueling can proceed with little or no pressure buildup in said fuel tank.

Claim 7

A fuel tank venting system for a domed fuel tank having a closed refueling mode of operation wherein the filler inlet is completely sealed uring refueling comprising: a filler pipe to said domed fuel tank having an open end, a first vent pipe on said tank having opposite open ends thereon, means defining a restricted flow path from the dome of said tank to said first vapor vent pipe, a second vapor vent pipe on said filler pipe adjacent the open end thereof having an unrestricted opening thereto, a cap for sealing the open end of said pipe including primary cap seal means thereon engageable with said filler pipe to seal thereagainst to prevent vapor flow from said first vent pipe through the open end of said filler pipe, coacting means on said filler pipe and said cap defining a secondary cap seal to seal between the tank and said second vent pipe to cause vapor flow from said tank to be controlled through said restricted path thence through said first vent pipe for flow to a charcoal canister for absorbing vapors during vehicle operation, said cap being removable from said open end of said filler pipe to open communication between said tank and said second vent pipe and to condition said filler pipe for a closed refilling phase of operation wherein the filler inlet is completely sealed, and means for connecting said second vent pipe with one of the open ends of said first vent pipe to direct unrestricted flow of vapor from said tank to said charcoal canisteR during a closed fill phase of operation with little or no pressure buildup in the fuel tank.

Claim 8

A fuel tank venting system for a domed fuel tank having a closed refueling mode of operation wherein the filler inlet is completely sealed uring refueling comprising: a filler pipe to said domed fuel tank having an open end, a first vent pipe on said tank having opposite open ends thereon, means defining a restricted flow path from the dome of said tank to said first vapor vent pipe, a second vapor vent pipe on said filler pipe adjacent the open end thereof having an unrestricted opening thereto, a cap for sealing the open end of said pipe including primary cap seal means thereon engageable with said filler pipe to seal thereagainst to prevent vapor flow from said first vent pipe through the open end of said filler pipe, coacting means on said filler pipe and said cap defining a secondary cap seal to seal between the tank and said second vent pipe to cause vapor flow from said tank to be controlled through said restricted path thence through said first vent pipe for flow to a charcoal canister for absorbing vapors during vehicle operation, said cap being removable from said open end of said filler pipe to open communication between said tank and said second vent pipe and to condition said filler pipe for a closed refilling phase of operation wherein the filler inlet is completely sealed, and means for connecting said second vent pipe with one of the open ends of said first vent pipe to direct unrestricted flow of vapor from said tank to said charcoal canisteR during a closed fill phase of operation with little or no pressure buildup in the fuel tank.