Fuel tank vent system and diaphragm valve for such system

A fuel system of the type including a fuel tank, a filler pipe for discharging fuel into the tank, a selectively closeable filler pipe inlet and a vapor trap for collecting fuel vapor vented from the tank, the fuel system further comprising:

• a rollover valve disposed between the fuel tank and the vapor trap;
• and
• a vent valve having a valve body, a vapor outlet to the vapor trap, and a vapor inlet from the rollover valve, a valve seat between the vapor inlet and the vapor outlet, a valve element matable with the valve seat, and a control element connected to the valve element for maintaining the valve element on the valve seal when the filler pipe inlet is at atmospheric pressure, and for displacing the valve element from the valve seat when the filler pipe inlet is at tank pressure, further including a fill control valve disposed between the fuel tank and the vapor trap, the vent valve including a second vapor inlet from the fill control valve and a second valve seat between the second vapor inlet and the vapor outlet, a second valve element matable with the second valve seat, and a second control element connected to the second valve element for displacing the second valve element from the second valve seat when the filler pipe inlet is at atmospheric pressure, and for maintaining the second valve element on the second valve seat when the filler pipe inlet is at tank pressure, wherein said first and second valve elements operate independently of each other.

A fuel system of the type including a fuel tank, a filler pipe for discharging fuel into the tank, a selectively closeable filler pipe arid a vapor trap for collecting fuel vapor vented from the fuel tank, the fuel system further comprising:

• a rollover valve;
• a vent valve;
• means connecting the rollover valve and the vent valve in series between the tank and the vapor trap;
• the vent valve having a valve body, a vapor outlet to the vapor trap, a filler pipe inlet, and a vapor inlet from the rollover valve, a first valve seat between the vapor inlet and the vapor outlet, a first valve element matable with the valve scat, and a first control element connected to the first valve element for maintaining the first valve element on the first valve seat when the filler pipe inlet is at atmospheric pressure, and for displacing the first valve element from the first valve seat when the filler pipe inlet is at tank pressure, further including a fill control valve and means connecting the fill control valve and the vent valve in series between the tank and the vapor trap, the vent valve further including a second vapor inlet from the fill control valve, a second valve seat between the second vapor inlet and the vapor outlet, a second valve element matable with the second valve seat, and a second control element connected to the second valve element for maintaining the second valve element on the second valve seat independently of the first valve element when the inlet from the filler pipe is at tank pressure, and for displacing the second valve element from the second valve seat independently of the first valve element when the inlet from the filler pipe is at atmospheric pressure, the vent valve connecting the rollover valve and the fill control valve in parallel.

In combination with a fuel storage tank for a vehicle having a fuel vapor canister, a fuel system comprising:

• a filler pipe having a selectively closeable inlet for discharging fuel into the fuel storage tank;
• a rollover valve connected between the tank and the trap to vent the tank when the vehicle is in a normal attitude and to close the tank when the vehicle is not in a normal attitude;
• a control valve in series with the rollover valve and operable between first arid second conditions;
• and
• condition-responsive means for operating the control valve in response to the vapor pressure conditions near the filler pipe inlet, further including a fill control valve connected between the tank and the vapor trap to vent the tank when the liquid fuel level in the tank is below a predetermined maximum, the control valve connected in series with the fill control valve, the control valve including first means for venting fuel vapor from the rollover valve to the vapor trap in the first condition and second means for venting fuel vapor from the fill control valve to the vapor trap in the second position, said first and second means operating independently of one other.

In combination with a fuel tank for a vehicle having a fuel vapor trap:

• a rollover valve connected to the fuel tank;
• a fuel-level responsive valve connected to the fuel tank;
• a control valve connected to the rollover valve, the fuel level responsive valve and the vapor trap, the control valve defining a first vapor flow path between the rollover valve and the vapor trap, and a second vapor flow path between the fuel level responsive valve and the vapor trap;
• and
• condition-responsive means for operating the control valve to alternately open and close the first and second flow paths the condition-responsive means including independent first and second valve elements.

In combination with fuel tank for a vehicle having a fuel vapor trap:

• a rollover valve connected to the fuel tank;
• a fuel-level responsive valve connected to the fuel tank;
• a control valve connected to the rollover valve, the fuel level responsive valve and the vapor trap, the control valve defining a first vapor flow path between the rollover valve and the vapor trap, and a second vapor flow path between the fuel level responsive valve and the vapor trap;
• condition-responsive means for operating the control valve to alternately open and close the first and second flow paths;
• a filler pipe for discharging fuel into the fuel tank and a selectively closeable filler pipe inlet, the condition-responsive means operating the control valve in response to pressure conditions near the filler pipe inlet;
• wherein the condition-responsive means include drainage means between the filler pipe inlet and the second vapor flow path.

In a vehicle fuel system of the type which includes a fuel tank, a filler pipe for admitting fuel to the tank, a selectively closeable filler pipe inlet and a vapor trap for collecting fuel vapor vented from the tank;

• a vent valve connected between the tank and the vapor trap said vent valve including first means for placing said vent valve in a first condition when the filler pipe inlet is closed and second means for placing said vent valve in a second condition when the filler pipe inlet is open, the vent valve comprising a valve body having a vapor inlet from the tank, a vapor outlet to the vapor trap, a valve seat between the inlet and outlet and a valve element biased toward and matable with said seat, said valve element being normally responsive to tank pressure to be displaced from said seat to provide vapor venting from the tank to the trap;
• a control element connected to the valve element and responsive to the net of atmospheric pressure in the filler pipe inlet and vapor pressure in the tank to maintain the valve element on said seat;
• drainage means formed in the valve element to permit liquid fuel to drain through the valve element regardless of the position of the valve element on the valve seat, the drainage means comprising a drain path formed in the valve element communicating with the filler pipe inlet and the fuel tank, the drainage means further including check valve means in the drain path for preventing reverse flow of fuel vapor from the fuel tank to the filler pipe inlet.