GB1076275A - Improvements in and relating to ignition devices - Google Patents

Abstract

1,076,275. Piezo-electric generators. SAPPHIRE-MOLECTRIC Ltd. Feb. 10, 1964 [Feb. 27, 1963], No. 7963/63. Heading H2A. [Also in Division F4] An ignition device comprises a pair of exposed electrodes 17, 19, Fig. 1 (Provisional Specification) in the region of the path of gas flowing into the atmosphere from valve 3, a piezo-electric member 6 in series with a spark gap between electrodes 17, 19, and means for manually stressing the member 6 to produce a gas igniting discharge across the gap. The spark gap is in the range 0À08 to 0À3 inch depending on the shape of electrodes (17, 19), Figs. 9 to 13, not shown. The member 6, comprising a pair of polycrystalline cylinders, is in a conductive housing 7 and supports a contact 8 insulated from the housing 7 by a piston 9. A plunger 12 on body 13 bears on a liquid-filled sac 10 between piston 9 and fixed partition 11. The member 6 is connected to electrode 17 via housing 7 and casing 1 and to electrode 19 by lead 18. Pressure on a push button 15 opens valve 3 through lever 21 and urges plunger 12 on to sac 10 the force being multiplied thereby and applied to the member 6. In Figs. 2-4 (not shown), a lever is used to depress plunger 12. In Fig. 5, the piezo-electric member 57 is mounted between rods 56 in a tube 55 and is compressed by moving a plate 62 inwardly to move a ball 58<SP>1</SP> across a pad 60. In Fig. 6, the piezo-electric member 60 extends beyond a recess 61 in a carrier 62 slidable in bore 63, member 60 bearing through pad 65 on a striker 66 extending into bore 67 in plate 68. A slide 69 and washer 72 guided by anvil 73, are biased upwardly by spring washers 74. Movement of lever 76 toward housing 64 causes lever 75 to move carrier 62 to compress washers 74, the conical head of anvil 73 moving slide 69 to register bores 70, 67 whereupon striker 66 moves rapidly down against anvil 73 resulting in rapid compression of member 60. In Fig. 7 (not shown), a plunger is prevented from compressing a fluid and hence the piezo-electric member until a certain pressure is exerted on the plunger and some balls are moved out of its path. A spring-biased plunger, Fig. 8 (not shown), is controlled by a sawtooth cam to rock a lever to alternately compress and release the piezo-electric member. In Figs. 14, 15 (not shown), rotation of lever (132) about (132a) allows valve (130) to open and causes lever (136) to move slide (137) to the left, a wedge (138) acting on plunger (139) to straighten out toggle (140, 141) to move a slider (144) acting on fluid-filled stainless-steel bellows (145), fluid from which acts on piston (148) to compress piezo-electric member (150) through pad (149). A slider which also actuates a lever to open the valve can also be used to operate this latter fluid mechanism. Fig. 16 (not shown). The gas is ignited primarily by ionization rather than simple heating; also a resistance or inductance is included in series with the piezoelectric member so that the spark rise time is within the range 28-280 microseconds. In certain cases a delay mechanism may build up successive potentials before application to the electrodes. Reference has been directed by the Comptroller to Specification 973,841.