Patent GB-515740-A (GB)
Title: Improvements in and relating to means for controlling the supply of gas to burners
IPC: F23N5/04
Filed: 1938-05-10
Abstract: 515,740. Safety cut - off valves SAFETY GAS DEVICES, Ltd., RABINOWICZ, M., and KESTENBAUM, I. May 10, 1938, Nos. 13995 and 35796. [Class 135] [Also in Group XI] A thermally - actuated safety cut - off valve is opened manually and retained in the open position by a catch moved by thermal means into both its operative and release positions, means being provided to prevent overstrain. In the form shown in Fig. 1, the gas cock is urged towards its closed position by a spiral spring d anchored at d<1> and acting on a disc c loosely mounted on the cock spindle. This disc has a pin b<1>adapted to engage a projection b on a disc secured to the cock spindle which has a handle a<1> for opening the cock. The cock is held in the open position by a pivoted catch e<2> engaging a projection c<2> on the disc c, said catch being in turn secured by a rack f engaging a projection f'. The rack which is urged towards the projection f<1> by a spring f<2> is secured by a screw 3 to one limb of a coiled bi-metallic strip g anchored at 2 to a base-plate 1. The strip is heated by a movable pilot burner h having a spherical enlargement h<1> held in a tubular part i by a spring h<2>. The burner is guided in a slot in an adjustable plate l and is connected by a spring k with an arm k<1> on the rack so that as the rack reaches one extreme position the burner snaps over to direct the flame more or less away from the thermo-sensitive member. In a modification the rack slides in guides and co-operates with a spring-pressed member slidably mounted in a socket on the locking catch. In a further modification the thermal strip is coupled to a member pivoted to the locking catch and provided with a spring pressed member adapted to co-operate with a toothed segment on the catch. The slip coupling may comprises two coaxial toothed discs resiliently pressed together. In the form shown in Fig. 4 the thermal strip is connected by an adjustable link t with a member n pivoted at n<1> to the catch member which turns on a pivot e' adapted to co-operate with stops on the member n to limit relative movement. A pawl r pivoted to the member n is connected by a spring s to the catch e<2>. As the thermal element expands the member n acting through the spring acts to move the catch into engagement with the projection c<2> on the plate c. Continued expansion moves the part n relatively to the catch and ultimately withdraws a tail on the pawl from a fixed pin r<3> so permitting the pawl to engage a projection w on the catch. On contraction of the thermal element the catch is positively released by the pawl and continued contraction brings the tail on the pawl into contact with the stop r' so withdrawing the pawl from the projection c<2>. In this form the pilot burner is turned against the action of a spring y by a projection on the link t. The pilot burner is fitted with a pyrophoric igniter operated by the movement of the cock handle. During rotation of the handle a projection 4, Fig. 6. on the handle engages a projection 5<1> on a member 5 pivoted to a lever 7 and so tensions a spring 11. The member 5 sliding over a fixed surface u<1> releases the catch 5<1> and allows the spring 11 to turn the lever 7. This lever. normally held against a stop 14, is connected by a coiled spring coupling with an abrasive wheel 8 and when turned rotates the wheel in contact with a " flint held in a carrier 9. This carrier is bifurcated to straddle the pin d', Fig. 4, and is slotted to receive a spring pressed arm 17 adapted to feed the " flint " forward.