Safety fuse with automatic underwater self-disarming

Abstract

A pressure-actuated fuse has a housing formed with an inner chamber and with a passage having an outer end opening to the exterior and an inner end opening into the chamber. A plug in the passage has a porosity sufficient to allow slow liquid flow through itself. An actuating element is exposed inwardly in the chamber and outwardly to the exterior and is displaceable in the housing by a pressure differential between the chamber and the exterior along an actuating axis between an outer position and an inner position. The chamber is substantially closed to the exterior except through the passage. A valve in the passage connected to the actuating element blocks liquid flow along the passage only when the actuating element is in its outer position. Thus, when the element moves out of its outer position liquid can flow through the plug and limitedly along the passage into the chamber. A spring braced between the housing and the actuating element urges it into its outer position so that only when the exterior pressure effective inwardly on the element is greater than the spring force can the element move into its inner position. A firing member is displaceable in the housing into firing position engaging and exploding a detonator therein. A link mechanism blocks the firing member from moving into the firing position except when the actuating element is in its inner position. Thus the interior of the device is cut off from the outside until the actuating member moves into its inner position, which normally only is when the device has been submerged fully.