Patent GB-190916849-A (GB)
Title: Improvements in Combined Temperature Indicating and Regulating Apparatus for Gaseous Fuel Furnaces.
Inventor: MACHLET GEORGE
IPC: C21D1/76
Filed: 1909-07-19
Granted: 1910-07-19
Abstract: 16,849. Machlet, G. July 19. [Addition to 11,840/09, Class 64 (ii), Heating systems &c.] Burners, regulating and controlling.-In apparatus for indicating and regulating temperature of the type described in the parent Specification, and in which the needle of a galvanometer or voltmeter operates to close an electrical circuit having means for regulating the supply of fuel and air to a furnace, means are provided for raising the fixed contacts out of the path of the needle after the closing of the circuit in order that the needle may also indicate subsequent variations of the furnace temperature, and two pairs of fixed contacts are provided in order to limit the fluctuations in the furnace temperature. A furnace 1, Fig. 1, having burners 2 supplied with gas and air through pipes 3, 4, respectively, and the regulating-valve 5, is provided with a thermo-couple 22 for deflecting the galvanometer needle 14 to an extent dependent upon the furnace temperature. The valve 5 is connected to a diaphragm 11 in a chamber 48 open on its underside to the pressure of air in the pipe 4 and also through a pipe 49, flexible tube 50, elbow 51 and valve 46 to the atmosphere. Upon the galvanometer needle 14 is pivoted a metal bridge 24, Fig. 7, the movements of which are limited by a U -piece 25, and which serves to bridge the fixed contacts 26, 27, Figs. 1 and 2, or 55, 56. These contacts are mounted on a rocking shaft 35, upon which is fixed an arm 34 carrying a weight 63, and contacts 33, 61, Fig. 9. An armature 32, Figs. 2 and 9, mounted between electro-magnets 31, 59 works upon a shaft 62, Fig. 10, independently of the shaft 35. This shaft operates by means of a sector 43, Fig. 2, and pinion 44, a shaft 45, Fig. 1, carrying at its end the relief valve 46. The arrangement of the electric circuits is shown diagrammatically in Fig. 9. When the part 24, owing to increases of the furnace temperature and consequent motion of the needle 14, bridges the contacts 26, 27, a small current flows from the battery or other source of electricity 30 through the wire 28 to a pivot screw 39, through the contacts 27, 26, wires 36, 37, and electro-magnets 31, and thus the armature 32 is drawn over until it touches the contact 33. This short-circuits the current from the screw 39 through the armature and the contact 33, and thus permits a larger current to pass through the electro-magnets 31, over to which the armature swings, pulling with it the arm 34. The motion of this arm is continued by the weight 63 after arrest of the armature by the magnet 31, and the shaft 35 is turned, thus raising the contacts 26, 27 out of, and placing the contacts 55, 56 in the path of the needle, and turning the valve 46, Fig. 1, through the gearing 43, 44, Fig. 2. The valve 46, now open, allows air to escape from the chamber 48, and the valve 5 wholly or partly cuts off the gas and air supplies. The instrument needle is free to indicate any alteration of the furnace temperature, and, as this falls, the contacts 55, 56 are ultimately bridged by the part 24. A current then passes through the wire 29, Fig. 9, screw 39, contacts 55, 56, and wires 57, 58, and excites the electro-magnets 59. The armature 32 is drawn over to touch the contact 61, and the current is thus short-circuited through the armature to the contact. A stronger current then passes through the electro magnets 59, and the armature 32 and arm 34 are thus drawn over together, turning the shaft 35 so as to remove the contacts 55, 56 out of the path of the needle and replace the contacts 26, 27. Simultaneously the valve 46 is closed by the gearing 43, 44, the diaphragm 11 rises and the fuel and air supply is increased. The contacts 26, 27, 55, 56 may be adjusted to any particular point on the scale by turning the table 64, Fig. 10, carrying the mechanism, about the screw 65, and a thumb-screw 66 which presses a friction block 68 against the table edge, may lock the table in position. The stroke of the arm 34, which is greater than that of the armature 32, is limited by stops.