Patent GB-430027-A (GB)
Title: Improvements in automatic pressure-responsive release mechanisms for work elements
IPC: A62C35/60
Filed: 1933-12-12
Abstract: 430,027. Fluid - actuated valves. BURGESS, A. F., 10, New Court, Lincoln's Inn, London.-(Automatic Sprinkler Co. of America; 910, Standard Bank Building, Cleveland, Ohio, U.S.A.) Dec. 12, 1933, No. 34956. [Class 135] [See also Groups XXI and XXV] Relates to release mechanism of the kind described in Specification 107,522, [Class 47 (ii)], adapted for releasing, either automatically or by hand, a work element such as a suspended weight adapted, when rerelased, to perform work such as the actuation of a fire door, an alarm, or an extinguishing apparatus. The weight is supported by a biassed lever normally locked by a train of levers terminating in sensitive escapement levers adapted to be actuated by a pressure-controlled diaphragm, and a single resetting member for the train of levers is controlled, as to its operation, by direct coaction with the weight-supporting lever. The weight 9 is supported by a link 9<a> with a rolling head 9<b>, on a weighted lever 8 fixed, outside a casing 1, on a shaft 10, Fig. 1. Fixed to shaft 10 inside the casing is a lever 4 the end of which normally engages under a shoulder 3<a> on a lever 3, Fig. 8, pivoted on a shaft 16. The lever 3 is biassed by a spring to turn counter-clockwise, but is restrained by the engagement of its inner end with the flatted end 17<a>, Fig. 3, of a shaft 17 to which is fixed a lever 6 weighted to tend to turn shaft 17 counter-clockwise. Lever 6 is held from movement by a pawl 20 on its inner end engaging a tooth 15<a> formed on a rotatable shaft 15. Fixed to the latter, and locking it, is a lever 14, the free end of which is shaped to engage a cam projection 12<a> on a lever 12, Fig. 5. The latter is locked by an escapement lever 13 the inner end of which contacts with a pin 52 engaging a diaphragm 43 clamped in a casing 44. The levers 12, 13 are pivoted to lugs carried by the casing 44. When the diaphragm is moved downwardly, the lever 13 is tilted in a clockwise direction, unlocking the train of levers, so that the lever 4 tilts and releases the weight 9. The diaphragm is moved by increased air pressure on its upper surface produced by automatic or manual devices. A passage 48 in the casing 44 is connected by a pipe 56, Fig. 3, to said devices. A vent tube 60 packed with fibrous wadding and protected by an apertured cap 62 allows slow pressure equalization above the diaphragm 43. The stiffness of the diaphragm is varied to vary the sensitivity of the release mechanism, and its central portion is strengthened by a plate 54. The lever mechanism is reset by an external lever 7, Fig. 1, which can only be moved to resetting position when the lever 8 has been returned to weight-supporting position. The lever 7 is fixed to a shaft 16 on which is fixed a lever 5. Clockwise rotation of the lever 5 returns the lever 3 to operative position by means of a cam surface 5<a> and roll 29, the lever 6 by means of a slotted link 24 and pin 6<c>, and the lever 12 by means of a bracket 27. The arrange ment of the mechanism is such that increase of the load on the lever 8 increases the sensitivity of the mechanism. In a modification, the diaphragm 43 and lever 13 are arranged to be actuated either by rise or fall of the diaphragm. Thus, the diaphragm is movable either by increased or decreased pressure above the diaphragm, or by increased pressure beneath it, such as might be caused by an explosion. In another modification, Fig. 12, the weight is supported by an arm 116 pivoted to the main lever 4 and normally held in weight-supporting position by a fusible link 120.