Fuel tank cap with pressure/thermal relief

A pressure relief valve for a tank comprising:

• a valve plug positioned outwardly of an opening in the tank defined by a tank body portion;
• biasing means for biasing the valve plug axially inwardly into a position in which it closes the opening;
• said biasing means comprising a spring;
• and said spring having an inner end located axially inwardly of the valve plug and the opening, and an outer end that engages said body portion;
• and
• a structure forming an interconnection between the valve plug and said inner end of said spring;
• said structure including an abutment that abuts said inner end of said spring, and fusible material positioned to maintain said interconnection;
• said spring being resilient to allow said structure and the valve plug to move outwardly in response to increased pressure in the tank to relieve pressure in the tank;
• and said fusible material being located inwardly of the valve plug and being meltable at elevated temperatures exceeding a predetermined level, to release said interconnection to allow the valve plug to move outwardly away from the opening.

In combination:

• a cap for closing a fuel tank filling and venting tube;
• said cap having a main body with an axial opening, and means for detachably engaging said tube;
• and
• a pressure relief valve comprising:
• a valve plug positioned outwardly of said axial opening in said body;
• biasing means for biasing the valve plug axially inwardly into a position in which it closes said axial opening;
• said biasing means comprising a spring;
• and said spring having an inner end located axially inwardly of the valve plug and said axial opening, and an outer end that engages said body;
• and
• a structure forming an interconnection between the valve plug and said inner end of said spring;
• said structure including an abutment that abuts said inner end of said spring, and fusible material positioned to maintain said interconnection;
• said spring being resilient to allow said structure and the valve plug to move outwardly in response to increased pressure in the tank to relieve pressure in the tank;
• and said fusible material being located inwardly of the valve plug and being meltable at elevated temperatures exceeding a predetermined level, to release said interconnection to allow the valve plug to move outwardly away from said axial opening.

Vented tank cap apparatus comprising:

• cap means for closing a liquid fill opening of a liquid container tank, said cap means including a cap member for covering said fill opening and having a main vent opening therethrough;
• valve means for closing said main vent opening, said valve means including a main valve member mounted on said cap member for normally closing said main vent opening in a closed position;
• resilient closure means for resiliently urging said main valve member into said closed position but allowing it to open when the pressure within said tank exceeds a predetermined pressure;
• and
• fusible means operatively coupled to the main valve member for closing the main vent opening and for releasing said main valve member and enabling it to move from said closed position to an open position when said fusible means melts, and
• in which the resilient closure means includes a coil spring having its upper end attached to the cap member and its lower end attached to a retainer member which is secured to said main valves member to resiliently urge the main valve member toward the interior of said tank.