Patent GB-1278985-A (GB)
Title: Emergency release latch arrangement for a hatch
Inventor: LYONS ROBERT JOSEPH
IPC: F24F7/02
Filed: 1969-09-09
Abstract: 1278985 Fire or explosion operated ventilators R J LYONS 9 Sept 1969 [21 Jan 1969] 44420/69 Heading A5A [Also in Division E2] An emergency release latch arrangement for restraining a hinged hatch cover 20 in closed position against a heavy spring bias, comprises bearing means 36 adapted to be fixedly secured to a fixed structural member 38 adjacent the hatch, a movable element 34 supported by the bearing means, a latching bolt 42 including a hook portion 46 adapted to engage a keeper 32 on the hinged hatch cover, the said latching bolt being pivotally mounted on the movable element for swinging the hook portion between engaged and released positions and being biased (by a spring 67) towards the engaged position, the movable element being movable between a retracted position and an extended position in the intended opening direction of the hatch cover, and lever means 50, 56 pivotally mounted on trunnion means 54 adapted to be fixedly secured to another structural member 16 adjacent the hatch the lever means having a short arm 52 adapted to engage and restrain the movable element in the retracted position and a long arm 56, and means restraining the free end portion of the long arm of the lever means, the said restraining means including a release means 62 adapted to release the said free end portion upon occurrence of a predetermined emergency condition, the said release means being adapted to allow the lever means to pivot to cause disengagement between the short arm and the movable element whereby, in use, the spring bias on the hatch cover will cause upward movement of the latch bolt and movable element and release of the latch bolt from the keeper. In the construction described and shown the arrangement restrains two hatch covers and consequently two bearing means 36, two elements 34 and two bolts 42 are provided; the lever means consists of a member 50 of U-shaped configuration and a member 56 secured to the central portion of the member 50; the member 50 is pivotally secured to the structural member 16 by the trunnions 54 and each of its end portions constitutes a said short arm 50 so that both hatch covers are released simultaneously when the lever means is pivoted by release of the emergency actuated release means 62. The emergency actuated release means 62 as shown is a fusible metal member intended to melt in the event of fire and the restraining means includes a second lever 60 and a catch 58 carried by the lever the catch 58 engaging the end portion of the member 56 of the lever means; when the member 62 fuses the lever 60 pivots clockwise so that the catch releases the member 56; this allows the lever means to pivot anticlockwise so that the short arms 62 release the members 34 which as shown slide in the bearing means 36. The bolts can also be released manually via a cable 70 a bar 68 and two cables 66. Instead of using a fusible metal link 62 a solenoid-operated pin can be provided which engages the end portion of the lever 60; the solenoid is controlled by suitable sensor device such as a photoelectric cell or bimetallic heat-operated switch located in an appropriate position in the building to be protected; the sensor device can also be operated by pressure rather than temperature where it is desired to cause the covers to open in case of explosion occurring in the building. A construction is also described for opening the covers in case of an explosion; in this construction the fusible link 62 is connected to the structural member 18 by a releaseable pin which is in turn connected to a bell-crank lever which can withdraw the pin to release the fusible link; the lever carries a panel which is pivoted upwardly in response to pressure of an explosion occurring in the building so withdrawing the pin and releasing the link so that the covers can open as previously described.