GB1100061A - Improvements in or relating to burner ignition units for gas appliances - Google Patents

Abstract

1,100,061. Gas burner igniters. STEVENS MANUFACTURING CO. Inc. 24 June, 1965 [9 July, 1964], No. 26833/65. Headings F4F and F4T. A burner ignition unit comprises a housing 10 through the lower portion 16a of a front plate 16 of which projects a pilot burner tube 11, and a thermal probe 13 which when heated by the pilot burner expands and operates a switch 14 positioned within a recess 20 of the housing. An ignition coil 15 is rigidly supported from the housing by legs 40b and 43b in a position to ignite the pilot burner which is formed with a ignition port 23 and flame ports 12. The outboard end of the thermal probe is slidably supported in a hollow adjusting screw 28 which is threadedly mounted in an end plate 24 of the pilot burner tube 11 and its opposite end extends through an aperture 21 in the plate 16 and is crimped over a rigid switch operating pin 27. The coefficient of thermal expansion of the probe is preferably substantially higher than that of the pilot burner tube 11. The switch, Fig. 6 (not shown) comprises a flexible leaf spring 30 fixedly riveted at one end to the ceramic housing body 17 by an electrically conducting rivet 33 which extends through the body 17 to the back of the housing and is attached to a first terminal 33a, Fig. 3 (not shown). Mounted on opposite faces of the spring at its other end are contacts 36 and 37 which confront fixed contacts 38 and 41 respectively. The fixed contacts are connected via electrically conducting rivets extending through the body 17 to second and third terminals 40a and 42a at the back of the housing, Fig. 3. The coil 15 is connected between third terminals 40a and a fourth terminal 43a fixed to the back of the housing. Fig. 7 shows the ignition unit connected into an oven burner ignition circuit. 46 represents a step-down transformer whose primary winding 47 is connected through a switch 48 across a mains A.C. current supply 49. The lower end of the secondary winding 45 is connected to terminal 33a and the upper end through time switch 50, thermostat 51 and conductor 59 to terminal 43a and to terminal 42a through an operating coil 52 for the electrically operated main burner gas supply valve 53. Switch 48 is manually controlled by a knob 57 which is also arranged to operate a pilot burner gas supply valve 58. Initially with the pilot burner unlit the switch spring is biased so that contacts 36 and 38 are closed and contacts 37 and 40 open as shown. Assuming that switch 50 and thermostat 51 are closed when the knob 57 is operated switch 48 closes and valve 58 opens so that gas is supplied to the pilot burner 11 and ignited since simultaneously the ignition coil will be energized. The heat of the pilot burner will cause thermal probe 13 to expand forcing the pin 27 against the switch spring whereby contacts 36 and 38 will open and contacts 37 and 41 close. The closing of the latter contacts will complete the energization circuit for the coil 52 opening valve 53 and permitting gas to flow to the main burner 54 to be ignited by the pilot burner.