Pressure and temperature relief valve with thermal trigger

A thermally activated relief valve for releasing fluid pressure from a fluid container when the relief valve reaches a predetermined temperature threshold, the relief valve comprising:

• a valve housing body having a fluid passage with an inlet for communication with the interior of the container, and an outlet;
• a seal, disposed within the fluid passage between the inlet and the outlet, sealing the fluid passage;
• a hollow bayonet mounted with the fluid passage between the seal and the outlet and movable between a first position, wherein the bayonet is spaced from the seal, and a second position, wherein the bayonet is piercing the seal;
• a thermal trigger disposed generally between the seal and the outlet causing the bayonet to move from the first position to the second position when the thermal trigger reaches the predetermined temperature threshold, the thermal trigger comprising a spring mounted within the valve housing biasing the hollow bayonet toward the seal;
• and
• a detent mechanism detaining a hollow bayonet in the first position when the detent mechanism is below the predetermined temperature threshold and releasing the hollow bayonet to move to the second position, under force of the spring, when the detent mechanism reaches the predetermined temperature threshold, the detent mechanism comprising a detent housing having an inner chamber, a detent movable within the inner chamber of the detent housing between a first position wherein the detent extends from the inner chamber of the detent housing to detain the hollow bayonet in its first position, and a second position wherein the detent is substantially entirely within the inner chamber of the detent housing thereby releasing the hollow bayonet to allow the hollow bayonet to move to the second position, and a temperature sensitive substance within the inner chamber of the detent housing, the temperature sensitive substance being in a solid state to hold the detent in its first position when the temperature sensitive substance is below the predetermined temperature threshold and in a liquid state allowing the detent to move to its second position when the temperature sensitive substance reaches the predetermined temperature threshold.

The thermally activated apparatus for releasing fluid pressure from a fluid container, the apparatus comprising:

• a valve housing having a passage;
• a seal for sealing the passage, the seal having a first side exposed to the fluid pressure and a second side opposite the first side;
• a hollow bayonet having a detent notch and being disposed within the passage, the bayonet being movable between a first position spaced from the seal and a second position wherein the bayonet pierces the seal;
• bias means, coupled to the bayonet, for biasing the bayonet toward the second position;
• a detent mounted to the valve housing and movable between a locking position wherein the detent is engaged within the detent notch on the bayonet holding the bayonet in the first position, and a released position wherein the detent is out of engagement with the detent notch so that the bias means moves the bayonet into its second position;
• and
• a thermally sensitive material holding the detent in the locking position when the thermally sensitive material is below a temperature threshold and melting to allow the detent to move to the released position when the thermally sensitive material reaches the temperature threshold.