GB613343A - Improvements in or relating to aircraft provided with automatic electric switches - Google Patents

Abstract

613,343. Fire-extinguishing. GRAVINER MANUFACTURING CO., Ltd., and MATHISEN, A. June 21, 1946, No. 18680. [Class 47 (ii)] [Also in Group XXXVII] A fire-prevention system for aircraft incorporates an inertia or impact-operated electric switch which is mounted adjacent the surface skin 13 of the aircraft, and puts fire-extinguishing apparatus into operation in the event of a crash. A pendulum 2, 3, is pivotally supported by a ball 4 within a frangible hood 17 clamped between a fixed frame 16 screwed to the skin 13, and a frame 12 held to the frame 16 by a screw 14 and a hinge 15. A ball 7 on an extension 2a of the shaft 2, engages the crater surface of a switch-closure -member 8 holding it in the open position against the pressure of a spring 9. The movable contacts 10 are mounted on an insulating support 11 on the member 8. If the pendulum is subjected to inertia forces or to direct impact, the ball 7 will ride over the rim of the crater in the member 8 allowing; the spring 9 to bring the contacts together, thereby energizing an electromagnetic relay z, Fig. 4, which operates the fire-extinguishing apparatus. Toprevent unwanted. inertia operation of the switch, a pin 24 attached to an armature 23 and urged downwards by a spring 29, engages in a hole in the ball 7. The switch is unlocked by energizing the solenoid 26 by---a---manually or inertiaoperated switch j ; also the pin 24 will shear if submitted to a severe impact. In Fig: 3, the switch is mounted on a structure-member 44 inside the surface skin and a cone 54 mounted on a relatively-weak part 53 of the skin deflects an impact-detecting rod 35 when the part 53 becomes distorted. The rod 35 is pivoted about a ball 34 held between the spring- loaded plates 38; 42, and is balanced so as to be unaffected by inertia. Displacement of a stud 36 attached to the ball 34 releases the spring-urged closure member 45, and brings the contacts 20, 47, together. The fireextinguishing containers f, g, Fig. 4, are, operated by a relay h actuated by the magnetic relay z controlled by the inertia or impact switches e or a crash switch i. Operation is also possible by push-button switches m should the warning lamps l controlled by a flame detector k be alight. Discharge of the container g is delayed by a switch n. Specification 423,223, [Group XXXVII], is referred to