Patent GB-708220-A (GB)
Title: Pressure-atomizing oil burners
IPC: F23D11/10
Filed: 1952-07-23
Abstract: 708,220. Liquid-fuel burners. GILBERT & BARKER MANUFACTURING CO. July 23, 1952 [Jan. 30, 1952], No. 18610/52. Class 75 (1) In an oil burner comprising a nozzle of the high oil pressure atomizing type and a fan for supplying air to mix with the atomized oil, and wherein a motor for driving the fan and pump is relieved of the load due to the oil pump at motor speeds below a predetermined value and a cut-off valve permits oil to be emitted from the nozzle only when the motor attains speeds above this value, the motor is a single phase induction motor of the shaded pole type having a low starting torque insufficient to start the pump when loaded resulting in a relatively long interval for the fan to established air flow before the emission of atomized oil from the nozzle, and having a small mass in its moving parts resulting in a low momentum after power to the motor has been cut off causing an early unloading of the pump and a quick closing of the cutoff valve. Fig. 4 shows a domestic oil burner in which a single phase electric induction motor of the shaded pole type, with laminated stator 75 and squirrel cage rotor 80 drives a fan 7 which supplies air to a conduit 9 containing an oil atomizing nozzle 13. The latter is supplied with oil through a pipe 24 by a pumping unit 25 comprising an oil pump and cut-off and pressure regulating valves and having a driving shaft 30 fixed to the driven element 31 of a speed responsive clutch, the driving element 32 of which is connected by a flexible coupling 33 of the hub of the fan 7. The clutch relieves the motor of the load of the oil pump until the fan is running at say 70 per cent. of its full speed, when it is engaged by centrifugally actuated means. The oil cutoff valve may comprise a hollow piston 53, Fig. 7, slidable in a sleeve 48 in a bore 47 and carrying a valve member 54 urged into' engagement with a seat 55 by an adjustable spring 57. Passages 45, 46 connect the outlet and inlet sides of the pump with the bore 47, and the valve 54 is opened when the oil pressure on the outer end face of the piston 53 reaches a predetermined minimum value. If the oil pressure rises to a higher predetermined value such that a hole 61 in the piston 53 is aligned with a groove 62 in the sleeve 48 part of the oil is by-passed from passage 45 through a passage 63, groove 62, hole 61, and the interior of the piston to the inlet side of pump. Thus the pressure of the oil supplied to the nozzle may be maintained substantially constant. In an alternative embodiment the oil pump shaft 30, Fig. 8, is directly connected by a flexible coupling 64 to the hub of the fan 7, so that it starts and stops coincidentally therewith, and the pump is initially unloaded by a small by-pass 65 formed in a disc 66 fixed to a diaphragm 67, which is clamped between cup-shaped casings connected by conduits 70, 71 to the inlet and outlet side of the pump. The by-passing continues until the output pressure rises sufficiently to close the by-pass 65 by moving the diaphragm 67 against the action of a spring 72 to engage the disc 66 with a valve member 72 carried by an adjusting screw 73.