US2283445A - Liquid fuel burner - Google Patents

Description

May 1 1942- BQG. LANGE LIQUID FUEL BURNER Filed March 6, 1940 2 Sheets-Sheet l May I9, 1942; B. ca. LANGE LIQUID FUEL BURNER I Filed March 6, 1940 2 Sheets-Sheet 2 Patented May 19, 1942 I LIQUID FUEL BURNER Broi- Gunnar Lange, Jonkoping, Sweden, assignor to Aktiebolaget Svenska Flttktfabriken, Stockholm, Sweden, a company of Sweden Application March 6, 1940, Serial No. 322,515 In Sweden March 7, 1939 9 Claims.

into fine particles which are flung directly into a current of combustion air through which the fuel particles are conveyed to the combustion chamber. More particularly, the invention relates to such liquid fuel burners in which the incl (:11 is conveyed to the brushing member by means of a rotatable cylindrical feeding memher on the surface of which an oil film is formed by the feeding member being rotated while partly submerged in oil.

in burners of the said kind the fuel particles thrown out from the brushing member are of a different size. On account of the rotation of the brushing member and the movement of the surrounding air caused thereby, a dispersion and separation of fuel particles of different sizes will take place, whereby the fine particles are caused to move to the one side and the larger particles to the other side of the stream of fuel. This fact is utilized according to the invention by shielding off part of the fuel stream so as to prevent the large fuel particles from entering the air current, the latter being thus supplied only with a finely divided fuel. Said dispersion of the fuel particles may also be utilized with advantage for controlling the amount of fuel supplied to the air current. To this end an adjustable shield is arranged to be introduced to different depths into the stream of fuel from that side of the stream where the larger particles are moving. By this arrangement it is made possible to vary the capacity of the burner during the operation without altering the speed of rotation of the brushing member or the feeding member respectively or without altering the thickness of the fuel film. In order to ascertain that substantially only finely divided particles are supplied to the fiow of combustion air, the latter is preferably conveyed against the fuel stream from that side of the brushing member which is opposite to the fuel feeding member. Preferably, the feeding member .is arranged below the brushing member, in which case the air is conveyed so as to strike the stream of fuel on its upper side.

The invention will be more fully described with reference to the accompanying drawings in is a vertical section of the burner through the line i4 in Figure l.

The combustion air is supplied to the interior of the burner by means of an enclosed ventilated electromotor 15 provided with bearing brackets or shields l7 and 18. The shield ll carries the brush casing l9, whereas the shield 13 carries a spiral-shaped fan casing 26 containing a fan 'wheel 22 mounted on an extension 2| of I the motor shaft. The air inlet opening of the fan casing is controlled by a throttle device in the form of a rotary disk valve the valve member 26 of which is rotatable about a journal 23. Part of the combustion air drawn in through the throttle valve, hereinafter called the primary air, is pressed through a special opening which Figure 1 is a front view of the oil burner,

25 in the end wall of the spiral shaped chamber 26 of the fan casing 29 and further through the motor housing into the brush chamber while passing through an elongated opening 21, Figure 4, in the end wall of the brush chamber. Before entering the free space of the brush chamber the air first passes a pocket formed by an'inner wall 28 which is adapted to deflect the air current towards the inner end of a tubular nozzle 30 of copper or other heat conducting material, through which the primary air is conveyed into the fire place. The remaining larger part of the combustion air drawn in by the fan 22, the secondary air, leaves the spiral chamber 26 through its proper outlet opening and passes through a.

conduit 32 containing a damper El operated by means of a handle 38, and through a spiralshaped passage 33 of a casing 35 surrounding outer tube 36. When leavingthe mouth of the tube last mentioned the rotating current of secondary air will mix intimately with the fuelair mixture leaving the nozzle 38. V

The outer tube 35 is provided at its mouth with an inner ring 31 extending outside the outer end of thenozzle 3B and adapted to contract the air passage. Said ring hasa conical inner end portion and a contracted outer end portion, whereby the current'of fuel-air mixture is caused to leave the burner at such a velocity as to keep the flame at a suitable distance from the mouth of the burner. As seen from Figures 2 and 4 the burner nozzle is tightly passed through a appear from Figures 1 and 4. Mounted on an extension 45 of the motor shaft is a cylindrical brushing member 45 consisting of a hub 47 keyed to the shaft by means of a screw 48, and a number of brush rings 49 spaced apart by means of elastic washers 59 and held together by means of washers and 52 and a nut 53 on the hub.

The brushing member 46 is arranged in frictional engagement with an oil feeding member 69 consisting of a cylindrical drum rotatably mounted by means of journals Si in a cradle 62 which is swingably mounted by means of journals 63 in the end walls of the brush casing. The cradle is located so as to cause the feeding drum to be forced against the brushing member with a constant pressure. The lower part of the brush chamber forms an oil reservoir which is supplied with oil so that the oil will be maintained at a constant level 64. The feeding drum 69 is partly immersed in the oil, whereby the cylindrical surface of the drum will be covered by an oil film when the drum is rotated. In order to suppress swinging motions of the cradle due to the roughness of the brushing member 49 the cradle is provided with a dash pot 55 normally filled with oil up to the same level as in the oil reservoir. The cradle also carries an oil scraper 68 consisting of a metal plate pivotally mounted on the cradle by means of pins 61 fixed to ears 98. The scraper bears with its free edge against the feeding drum thus reducing the oil film to the proper thickness. By means of flaps 69 oil is swept off also from the end surfaces of the feeding drum 60.

The direction of rotation of the brushing member and the feeding drum is indicated by arrows 85 and 85 respectively in Figure 4. It is essential for the proper function of the atomizing device that the feeding drum rotates at a speed which is essentially less than the speed of rotation of the brushing member. This may be effected by means of a retarding device of any kind that may be enclosed within the drum and which is not shown in the drawings.

When the brushing member and the feeding drum are rotated, subdivided particles of oil are projected from the brush in diiferent mutually diverging directions lying substantially between the dot-and-dash lines 88 and 89 in Figure 4 and extending upwards along tangential planes touching the periphery of the brush near the place of contact between the brush and the drum. The largest particles will then follow substantially the lower path 89, whereas the smallest particles will follow substantially the upper path 88. This dispersion and separation of particles of different sizes is due to the quick rotation of the brushing member and the rotary movement of the surrounding air caused thereby, the air causing a greater deflection of the path of the small particles than of the path of the large ones. Generally, it is desirable to utilize in the first instance the fine fuel particles contained in the upper part of the fuel stream. To this end the feeding drum 60 is placed in such a position relatively to the brushing member 46 as to prevent the larger particles from entering the nozzle mouth 29 said particles being shielded off by the portion of the brush casing located below the mouth. The oil thus deposited on the wall is prevented from fiOWing into the nozzle 30 by a flange 99 projecting from the wall below the mouth 29.

Projecting into the stream of subdivided oil is 7 a separate shield which is adjustable so as to allow a variation of the capacity of the burner by shielding off a larger or smaller part of the oil stream. Such an adjustable shield is shown in Figure 4. It consists of an angularly bent plate 9! pivotally mounted in the end walls of the brush chamber by means of a spindle 92 which is parallel with the axis of rotation of the brushing member. A slot 93 is provided in the bent portion of the shield so as to allow oil collecting on the upper side of the shield to be drained off. As shown in Figure 2 the spindle 92 extends through the brush casing and along the rear side of the burner to a bearing in the conduit 32. It is provided at its free end with a control lever 94, which is adapted to engage with its fork-shaped enda pin 95, Figure 3, on a projecting part of the valve member 24. By this arrangement the valve 24 will be operated simultaneously with the shield 9| upon actuating the control lever 94. A set screw 96 is arranged to co-operate with the control-lever so as to prevent the flame from being put out by the combustion air being throttled or the fuel stream being shielded ofi too much. The control lever 94 is loaded by a weight 97 tending to keep the valve 24 and the shield 9| in the end position in which the supply of air and oil is a minimum. Preferably the control lever 94 is operated by a thermostat so as to obtain an automatic adaptation of the flame to the demand of heat.

The burner operates as follows. When starting the motor the brushing and feeding members will be rotated and combustion air will be pressed through the burner as above described. The oil film conveyed to the brush 46 by the oil drum 60 is subdivided into a stream of small particles directed substantially towards the inner mouth of the nozzle 39 and against the current of primary air passing through the upper part of the atomizing chamber. The fuel-air mixture thus obtained is conveyed through the nozzle 30 and mixed with the rotating secondary air supplied through the surrounding passage 35. This mixture having been ignited, the size of the flame may be controlled by turning the control lever 94 in the one or the other direction. Upon turning the lever 94 in a clockwise direction in Figure 3, the valve 24 will be turned in a counter-clockwise direction while reducing the inlet openings for the combustion air and the amount of primary and secondary air supplied to the burner. At the same time the shield 9| is turned in a clockwise direction in Figure 4, whereby the amount of subdivided fuel supplied to the burner nozzle is also reduced. If, on the other hand, the controlling lever 94 is turned in the opposite direction, the amount of combustion air as well as the useful amount of subdivided fuel is increased. By adjusting the total supply of combustion air relatively to the shield 9| and by properly adjusting the supply of secondary air by means of the damper 3|, it is possible to obtain the most suitable fuel air mixture for each position of the controlling lever 94.

I claim:

1. A liquid fuel burner comprising means for forming a film of liquid fuel, a brushing member positioned to contact said film, means for rapidly rotating said brushing member to cause the fuel film to be dispersed in a stream of finely divided particles of varying sizes, means for conveying an air current towards said stream to form therewith a fuel-air mixture, and shielding means projecting into said stream at that portion of said stream which carries thelarger of said particles so as to prevent part of the subdivided fuel from reaching the air current,

2. A liquid fuel burner as claimed in claim 1, in which the free edge of the shield extendssubstantially along a radial plane through the axis of rotation of the brushing member.

3. A liquid fuel burner as claimed in claim 1, in which the shield is adjustable and arranged to be moved into the stream of subdivided fuel substantially in a direction which is perpendicular to the axis of rotation of the brushing member.

4. A liquid fuel burner as claimed in claim 1, in which the air current is directed against that side of the stream of subdivided fuel which is opposite to the shielding means.

5. A liquid fuel burner as claimed in claim 1, in which the stream of subdivided fuel is carried through a free space in a horizontal or upin which the shield is swingable about an axis parallel with the axis of rotation of the brushing member.

8. A liquid fuel burner as claimed in claim 1 in which the shield is coupled with a device for controlling the supply of combustion air so as to allow a simultaneous control of the supply of fuel and air. 7

9. A liquid fuel burner comprising means providing a chamber having an outlet for a fuelair mixture, a fuel feeding member in said chamber for forming a film of liquid fuel, a brushing member in said chamber positioned to contact said film, means for rapidly rotating said brushing member to disperse said film and project the fuel in finely divided state into space in said chamber in a path directed generally toward said outlet, means for creating an air stream flowing through said chamber to said outlet from a place on the side of said brushing member remote from said fuel feeding member, whereby to cause the dispersed fuel and air to meet in said chamber to form a fuel-air mixture for delivery to said outlet, a shielding member in said chamber on the side of the path of dispersed fuel remote from said air stream for preventing fuel on said remote side from reaching and mixing with said air, means for adjusting the position of said shielding member to vary the quantity of fuel reaching said air stream, control means'for varying the quantity of air admitted to said chamber, and means interconnecting said control means and said shielding member for causing said control means to reduce the quantity 'of air admitted to said chamber on adjustment of'said shielding member to reduce the quantity of fuel reaching said air streamand vice versa.

BROR GUNNAR LANGE.

Images