US2291046A

US2291046A - Arrangement for burning liquid fuel

Info

Publication number: US2291046A
Authority: US
Publication date: 1942-07-28
Anticipated expiration: 1959-07-28

Description

July 28, 1942. K, H, LANGE 2,291,046

ARRANGEMENT FOR BURNING LIQUID FUEL Fi1 ed Dec. 21, 1938 4 Sheets-Sheet 1 i .35 I 37 J9 July 28, 1942. K; H, LANG: "2,291,046

ARRANGEMENT FOR BURNING LIQUID FUEL Filed Dec. 21, 1938 4 Sheets-Sheet 2 IN VEN To 1? July 28, 1942. LANGE ARRANGEMENT FOR BURNING LIQUID FUEL,

Filed 'Dec. 21, 1938 l 4 Sheets-Sheet 3 Iii ' AIATTORNEY.

K. H. LANGE 2,291,046 ARRANGEMENT FOR BURNING LIQUID FUEL I v July 2 1942;

Filed Dec. 21, less IvvEA/TOR ki wg Patented July 28, 1942 UNETED ST TENT OFFICE Application December 21, 1938, Serial No. 247,135

In Sweden December 1, 1933 10 Claims.

This application is a continuation-in-part replacing my co-pending application Serial No. 752,356, filed November 9, 1934, and relating back thereto for all dates and rights as to common subject matter.

The present invention relates to liquid fuel burners and has particular reference to bumers for fuel oils, of the kind in which the fuel is mechanically prepared for combustion by subdivision of the liquid into fine particles appropriate for intimate mixture with combustion air, which sub-division is ordinarily referred to as atomization. I

Amongst the principal objects of the invention are: to provide a burner which is simple and rugged in construction; to provide a burner the operation of which is not dependent upon the proper functioning of fine orifices that are likely to be clogged by solid impurities contained in the fuel; to provide a burner of the mechanical atomizing type which can be designed for and will operate satisfactorily with unusually small capacity; to provide a burner capable of operating eificiently and without detriment to the degree of atomization effected, through a wide range of capacities; to provide a burner capable of ready regulation with respect to capacities; to provide a burner permitting simple and effective control of the fuel air ratio of the mixture delivered by the burner at different capacities; to provide a burner permitting regulation ofthe degree of atomization of the fuel to be effected; and to provide a burner capable of satisfactorily atomizing relatively heavy and viscous fuels.

The manner in which the above objects and other and more detailed objects are advantageously secured, together with the advantages to be derived from use of the invention, will appear more fully in the ensuing portion of this specification, taken in conjunction with the accompanying drawings, in which various form of apparatus for carrying the invention into effect are described and illustrated.

In the drawings:

Fig. 1 is a vertical section taken on the line ll of Fig. 2 and showin one form of apparatus embodying the principles of the invention;

Fig. la is a plan view on a smaller scale of the apparatus shown in Fig. 1;

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is a section taken on the line 33 of Fig.2;

Fig. 4 is an end elevation of another form of apparatus embodying the invention;

Fig. 5 is a section taken on the line 5-5 of Fig. 4 and on a larger scale;-

Fig. 6 is a section taken on the line 6-B of Fig. 5 and on the same scale as Fig. 4;

Fig. '7 is a more or less diagrammatic view showing a burner installation embodying certain principles of the invention as applied to the embodiment of burner shown in Figs. 1 to 3; and

Figs. 8 to 12, inclusive, are diagrammatic sections illustrating other forms of apparatus for carrying the invention into effect.

Referring now more particularly to Figs. 1 to 3, the burner illustrated comprises a rotary brushing member lb of cylindrical form having brushing elements or bristle extending in generally radial direction, which bristles may be of metal, fibre, animal bristles, or other suitable material.

The brushing member is mounted on a shaft ll journaled in a housing I2 provided with a detachable cover I3 and is driven from any suitable source of power as, for example, the electric motor Ila shown in Fig. 1a, coupled directly to the shaft II. For reasons which will hereinafter more fully appear, the brushing member is driven at relatively high speed and in many in-- stances is preferably of the constant speed variety. The end surfaces of the brushing member Ill are protected by metal discs M provided with a number of fan blades or wings [5.

Immediately under the brushing member a retatable fuel feeding member I6 is located, this member being in the form of a smooth cylinder. The fuel feeding member is adjustably mounted in the housing So as to be movable toward or away from the brushing member to vary the pressure with which the brushing member bears against the feeding member. In the present embodiment this adjustable mounting comprises a U-shaped part ll, between the arms of which the member [6 is journaled. One arm of the member I1 is provided with a pivot l8 journaled in a bushin l9 screwed into the Wall of the housing I2.

The free end of pivot I8 has fixed to it an arm 20 loaded with a weight 2| adjustable along the length of the arm. The other arm of the member I? is journaled at 22 on a pivot bushing 23' secured in the Wall of the housing in line with the pivot IS. The outer end of the bushing 23 provides a brake surface 24 cooperating with a corresponding brake surface formed on the hub of a fan 25 operating in the air outside the housing. Fan 25 is mounted on a shaft 26 journaled in the bushing 23. The inner end of the shaft carries a small gear wheel 2'! meshing with a larger gear 28 fixed to a hub portion of the fuel feeding member IS.

The lower part of the housing l2 forms a reservoir or sump for the liquid fuel. Fuel is supplied to this reservoir through a supply pipe 29 and the level of the fuel is kept within predetermined limits of variation by any suitable form of constant level feeding mechanism, one form of which will hereinafter be described in detail.

An outlet duct'35 is formed to extend from the upper portion of one of the side walls of the housing l2, the inlet of the duct preferably being generally rectangular in shape and extending laterally for the full length of the brushing member l directly opposite the line of contact between the brushing member and the fuel feeding member. The area for flow through the outlet duct can be varied by means of an adjustable damper 36. A shut-01f member in the form of a wicket 3'! is provided in the outlet duct, the wicket being hinged at one end by hinges 38 and maintained in the lifted position shown in Fig. 1 by means of a low melting point member 39 which fuses if brought into contact with flame, to allow the wicket to fall. 40 represents a portion of the combustion space in the fire box of a boiler or the like.

Thesu-pply pipe H for air opens into the housing 12 through the wall of the latter opposite the outlet duct 3.5.

Air for combustion is advantageously supplied from a fan or the like, such as the fan Ma, connected to the motor for driving the brushing member, as shown in Fig. la, and the quantity of air supplied to the interior of the housing can be adjusted by suitable means such as a damper 42.

The U-shaped member I! carries a scraper which in the present instance consists of a strip 43 of flexible material carried by a holder '44 and bearing against the feeding member. In the present embodiment the scraper bears against the drum due to its own weight and that of the holder 44 which is pivotally mounted on the member I'I.

Operation of the embodiment just described is as follows: When the motor Ila or other source of power is started, the brushing member is caused to rotate in the direction indicated by the arrow. The brushing member is rotated at relatively high speed. The position of the weight 2| is adjusted to counter-balance the weight of the feeding member so that the latter is in contact with the brushing member. Also, the lower portion of the feeding member is immersed in the fuel contained in the reservoir at the bottom of the housing,

Friction between the bristles moving at high speed across the upper part of the feeding member causes the latter to rotate and adhesion of fuel to the surface'of the feeding member causes the liquid fuel 'to be carried to the top of the drum in the form of a layer or film which is made substantially even and of suitable thickness by the time it reaches the top of the feeding member, through the action of the scraper 43. The fuel feeding member thus feeds continuously to the brushing member a film of fuel which is brushed from the surface of thefeeding member in the form of extremely small particles by the individual :bristles of the brushing member. Due to the high rotation of speed of the brushing member, the fine particles brushed from the surface of the feeding member are thrown by the actionof centrifugal force into space in the general direction of the outlet duct and in the form of a fine mist. Movement of the fuel particles to the combustion space is facilitated by the current of air forced through the brushing or atomizing zone and out through the duct 35.

The fuel air mixture is ignited at the mouth of the outlet duct and due to the high velocity of the air passing through this duct the flame is prevented from entering the housing. If for any reason the flame should accidentaly flare back into the housing through the outlet duct, damage to the interior of the burner is prevented by the melting of the member 35, thus dropping the wicket 31 to shut the outlet. With the outlet for air from the burner closed, additional fresh air cannot be forced into the burner housing and any flame therein is extinguished by choking. The wicket arrangement is advantageously designed so that if it falls it may readily be reestablished in the position shown in Fig. 1.

The fan blades 55 on the brushing member prevent the formation of a stagnant combustible fuel-air mixture in the space between the end walls of the brushing member and the housing, which mixture if ignited might cause damage.

By adjusting the position of the weight 2! on the arm 20, the pressure with which the fuel feeding member bears against the brushing member may be varied and such variation in .pressure will obviously cause variation in the amount of friction between the two and variation in the speed of rotation of the fuel feeding member. Variation in speed of rotation of the fuel feeding member operates to vary the quantity of fuel supplied to the atomizing zone per unit time and consequently operates to vary the capacity of the burner.

For any given position of adjustment of the weight 2|, the speed of the fuel feeding member is maintained substantially constant by the action of the fan 25. The fan shaft 26 has longitudinal movement in the bushing 23 and the reaction of the fan 25 causes the brake surface of the fan hub to bear against the brake surface 24 of the bushing. With increase or decrease in speed of the fan, which is proportional to the speed of the feeding member, the frictional resistance provided by the brake increases or decreases and thus provides automatic stabilizing means for maintaining substantially constant drum speed for any given position of adjustment of the weight.

Various other means for obtaining variation in the capacity of the burner may be employed and in Figs. 4 to 6 there is illustrated another embodiment of burner structure providing for variable capacity and also control of the fuel air mixture delivered by the burner at difierent capacities.

Referring now to these figures, the housing of the :burner is indicated at 2 l 2, the housing being provided with a removable cap 2I3 and there being provided an outlet duct 235 similar to that described in connection with Fig. 1.

The brushing member 2 I 0, in the form of a cylindrical brush, is mounted on shaft 2| I which is journaled in suitable bushings in the housing structure. In the lower or reservoir portion of the housing, to which fuel is admitted through the feed pipe 229, there is rotatably mounted in suitable bushings the feeding member, in the form of a cylindrical drum 2 [6. The distance between the drum and the brushing member is fixed so that there is no variation in the degree of pressure contact between the bristles of the brushing member and the surface of the feeding member. A scraper 243 is provided which in the present instance may advantageously be relatively rigid and which as shown is adapted to be held against the surface of the feeding member with predetermined pressure by means of an adjusting screw 243a. It will be evident that if the adjusting screw is backed off, gravity load on the scraper may be utilized in place of a fixed pressure.

Air is admitted to the interior of the housing under the control of an adjustable damper 242 from an inlet passage 24! connecting the interior of the housing from a fan-compartment in which is located fan 241a. This fan is secured to the shaft 2 of the brushing member and the fan and brushing member are driven by means of the motor 2| la.

One end of the shaft 2 extends through the housing and has mounted thereon a friction disc 250 which is fixed against rotational movement with respect to the shaft by means of pin 25L The disc is mounted for axial movement on the shaft, the hub portion being slotted to receive the ends of the pin 25l and the disc being backed by a spring 252 tending to push the disc outwardly from the housing. A second friction disc 253 of larger diameter than disc 250 is mounted in like manner on the projecting end of the shaft carrying the feeding member 2I6. Disc 253 is held against rotation relative to this shaft by means of pin 254 and is backed by a spring 255. A vertical shaft 256 is fixed in support brackets 251 and 258 in alignment with the centers of the

discs

250 and 253. Rotatably and slidably mounted in shaft 256 is a friction member 259 carrying a horizontal friction disc 260 of relatively large diameter and a friction disc 26! of smaller diameter. Discs 250 and 26l are spaced apart on member 259 so that the former makes contact with the disc 25!! and the latter makes contact with the disc 253.

The backing springs 252 and 255 hold the

discs

259 and 253 respectively in frictional contact with the discs with which they cooperate. From Fig. 5 it will be evident that the relative diameters of the several discs is such as to provide a substantial speed reduction between the shaft of the brushing member and the shaft of the feeding member and also that the speed ratio between the two shafts may readily be altered by shifting the friction member 259 up or down on shaft 256. Upward movement of the member 259 from the position shown operates to reduce the speed of the shaft of the feeding member relative to the speed of the shaft of the brushing member and the speed of the former is increased relative to the speed of the latter upon downward movement of the friction member.

Preferably, the motor 2lla operates at constant speed, although for some purposes it may be desirable to vary the speed of the brushing member as will hereinafter be more fully explained.

The position of the friction member 259, which governs the speed of the feeding member, may be controlled in a variety of suitable ways and is advantageously arranged so that interconnected control is effected between the feeding member and the damper which controls th amount of air admitted to the burner housing.

In the present embodiment this interconnection is provided by means of a control lever 262 fixed I to the shaft 242a of the air control damper 242 and having a cam end 263 bearing against one end of a lever 264 pivoted on the housing at 265 andhaving an arm 266 operating in a suitable groove in the friction member 259. A suitable control rod 261 isattached to the lever 262 and may be operated manually or connected to any suitable thermostatic or like controlling element. As will be evident from Fig. 4, movement of the control rod 261 to the left from the position shown will operate to open the damper 242 to admit an increased quantity of air to the interior of the housing from the fan chamber and this movement will also permit the friction member to move downwardly from the position shown, thus increasing the rate of rotation of the feeding member and the quantity of fuel fed to the brushing member. It will be evident that by suitably contouring the profile of the cam end 263 of the control lever, any desired fuel-air ratio can be secured for different load values and either maintained constant throughout the load range, or varied if desired.

This control provides very simple and effective variable load operation with cheap and simple equipment since the motor may be of a simple constant speed type and control may be had effectively without requiring any electrical speed control.

It will be evident that a certain amount of dispersion of the atomized fuel brushed from the feeding member will take place and in order to prevent discharge from the burner of relatively large drops of fuel which might be formed on the inner surface of the outlet duct and be blown therefrom by the combustion air, the mouth of the duct is advantageously provided with a shield 268 having an inturned lip 259 serving to trap surface accumulations of fuel that might be blown along the upper wall of the outlet duct. Fuel thus trapped drains around the lip onto a second shield 210 spaced from the lower wall of the duct and having an upturned lip 2' at its outer end. Fuel on the inclined surface of the shield 21!] drains back to the reservoir portion of the housing.

Spacing of the shield 210 from the lower wall of the outlet duct provides a channel through which additional or secondary and substantially fuel free air may be discharged from the burner and with the burner arrangement illustrated, the mouth of the burner may, if desired, be spaced as shown in Fig. 4 from the opening of the combustion chamber indicated at 240 so that sec ondary air may be drawn in under the influence of the natural draft created by the combustion.

It will be evident that under different circumstances diiferent arrangements may be emp oyed so that the air supplied by the fan may in some instances provide all of the air for combustion, while in other instances it may provide only the primary air.

In both of the embodiments of apparatus hereinbefore described, the feeding member is maintained partially immersed in fuel and preferably the fuel is kept at substantially constant level although it will be evident that a material variation in the level of the fuel in the reservoir may take place without affecting the operation of the burner.

Fig. '7 illustrates one form of apparatus for providing constant level feed to the burner, which apparatus may be considered, in effect, as a part of the burner structure. In the figure this apparatus is shown as applied to the embodiment of 9 burner illustrated in Fig. 1.

Referring now to Fig. 7, a main storage tank 80 is shown which is placed in communication with a hermetically closed auxiliary tank or vessel 83'by means of a pipe 8| which advantageously is provided with a manually controlled shut-off valve 82. The auxiliary storage tank communicates through the feed pipe 29 with the lower or reservoir portion of the burner housing. The outlet end of the pipe 8| is provided with a valve seat 84 and the inlet end of pipe 29 with a valve seat 85, both of which seats are located within the vessel 83. These seats cooperate respectively with valve cones86 and 81 mounted atthe ends of a lever 89 centrally pivoted at 88 so that one of the valves is opened when the other is.closed, and vice versa. Lever 89 is arranged to be shifted by means of a bell crank lever 90 pivoted at 88 and having arms of different length. The longer arm carries a float 8| at its free end and the end of the shorter arm is connected by means of a tension spring to the end of an arm 93 extending perpendicularly from the center of the lever The air space above the free level of liquid in the closed vessel83 is placed in communication by means of the control pipe, which has a relatively large diameter, with the lower portion of the burner housing, this pipe opening into the housing at the level desired for the free surface of the fuel in the burner housing. The vessel 83 is constructed so that there is the smallest possible volume of air space in this vessel when the float 9| occupies its uppermost position.

Operation of the above described apparatus is as follows, it being assumed that the vessel 83 is filled with fuel to the level indicated in the figure. The float 9| then occupies its upper limiting position and the line of connection between the ends of the spring 92 is to the right of the pivot 88 so that the spring tends to turn the lever 89 to the right, in which position the valve controlling flow from the main storage tank is closed and the valve controlling the feed line to the burner housing is open. It is further assumed that the level of the fuel in the housing is sufficiently high to form a trap in the control pipe 38. In this state of'equilibrium the free surface of liquid in the pipe 30 is at the same level as the free surface of the liquid in the vessel 83, the pressure in the air space above this liquid level being sufficiently below atmospheric to balance the difference in level between the free surfaces of the liquid in the two communicating vessels I2 and 83.

As fuel is carried by the feeding member to the brushing member, the level of the liquid in the burner housing drops to a point such that eventually the upper part of the mouth of the control pipe is exposed and air then flows upwardly through the liquid in this pipe to the spaceat the top of the vessel 83, permitting a correspending volume of fuel to flow from this vessel through the pipe 25 to the reservoir in the burner housing. This flow continues until the level of the liquid in the housing rises to a point covering the mouth of the control pipe 30, at which time the flow ceases. This operation is repeated at intervals depending upon the rate at which fuel is delivered from the burner, and the level in the burner is kept constant within relatively narrow limits.

As fuel is delivered from the vessel 83, the resultant lowering of the float 9| causes the lower end of the bell crank lever 90 to move to the left asviewed in the figure, and when such movement is sufficient to cause the line of connection of the spring to move to the leftof the pivot 88, the lever 89 will be snapped over by the spring to open the inlet from the main storage tank and to close the delivery line 89 leading to the burner housing.

When this occurs, the auxiliary vessel 83 is refilled until the level reaches a point where the lever 89 is caused by the spring to snap back to the position shown in the drawings. When the auxiliary vessel is refilled, the air in the upper portion of this vessel is displaced by the incoming liquid through the control pipe 30. The main storage tank and supply pipe 8I are made such that the refilling of the auxiliary vessel is accomplished rapidly, so that during the filling period the level of fuel in the burner housin will not drop sufliciently to cause interruption of feed to the brushing member.

It will be apparent that the apparatus just described provides means whereby fuel containing a considerable amount of solid or semi-solid impurities may be utilized without incurring danger of clogging of the burner since no small orifices need be interposed between the main storage tank and. the outlet of the burner from which the fuel is delivered in atomized state.

The toggle action of the feeding mechanism maintains the control valves either in fully closed or fully open position so that these valves do not operate as throttling orifices and it is evident that the burner structure is free of any fuel restricting orifices which might become clogged by such impurities. In the case of extremely dirty fuel, a filter may advantageously be used in order to avoid accumulation of sludge in the base of the burner housing, but if such sludge should accumulate, it will be evident that means may readily be provided for its removal through a suitable drain plug in the base of the burner.

For heating boilers and the like it is usually desirable to keep temperature or pressure substantially constant by automatic regulation of the output of the burner. Such an arrangement is shown in Fig. '7 wherein a thermostat or pressure regulating member indicated at I00 is shown connected by means of the lever IOI and a connection I82 to the arm I03 connecting the air damper 42. A further connection is provided by wire I04 and the coil spring I05 to the end of the weight-loaded arm 20 which regulates pressure of the fuel feeding member I8 against the brushing member ID.

This regulating arrangement operates as follows: When the boiler is cold, or pressure is low, the wire connection I02 is slack so that the damper 42 is in fully open position and the loaded arm 28 presses the feeding member against the brushing member with the maximum pressure corresponding to the adjusted position of the weight 2I on the arm. Under these conditions maximum capacity for the adjusted condition of the burner is obtained. Upon rise of temperature or pressure the arm IOI is lifted, causing the damper to be moved toward closed position. Simultaneously, the spring I05 is placed under tension and acts to reduce the effect of the weight 2| on the arm 20 so that the pressure of the feeding member on the brushing member will be reduced. This will result in reducing the speed of rotation of the feeding member and consequently the amount of fuel delivered by the burner will also be decreased.

' It will be evident that similar control of burner capacity may be obtained by connecting the control rod 281 of the burner illustrated in Fig. 4

to any suitable heat or pressure responsive element.

If constant speed of operation of the brushing member is employed, which because of simplicity is in many instances desirable, it will be evident that a wide range in burner capacities may be effected without in any way impairing the degree or quality of atomization. With most mechanical atomizing burners, the quality of atomization is reduced when the capacity of the burner is reduced, but with the present burner even finer atomization may be expected at low capacity than at higher capacity since fuel is fed to the brushing member at a lower rate while the speed of the brushing member, and consequently the number of atomizing bristles coming into contact with the fuel film, remains constant.

In some instances it may be desirable to deliberately vary the degree of atomization and this may be accomplished by varying the speed of operation of the brushing member while maintaining the rate at which fuel is fed to it constant by speed or varying at a different rate the delivery of fuel to the brushing member.

Also, variable degrees of atomization can be effected by varying the thickness of the fuel film on the feeding member by adjustment of the scraping member. This may also be accomplished by changing the viscosity of the fuel, by heating it in the storage tank or by heating the fuel feeding member itself, or both.

It will be apparent that different degrees of atomization may be desirable for burners of different size used for different purposes, and the basic degree of atomization desired may readily be secured by suitable selection of the material, spacing, etc. of the bristles of the brushing member.

It will also be evident that arrangements other than those described may be employed for driving the feeding member. If desired this member can be driven independently of the brushing member, as for example by a variable speed electric motor.

While the embodiments previously described are to be preferred because of their simplicity, other fuel feeding arrangements may be employed.

In case a very heavy and viscous fuel is burned, the scraping arrangement shown in. the preceding embodiments may be replaced by an arrangement of the kind indicated diagrammatically in Fig. 8. In this arrangement the fuel feeding member I6 is placed above the level of the fuel in the housing and fuel is carried to it by a drum partially immersed in the fuel and contactin the feeding member I6, preferably with adjustable pressure, to transfer to the feeding member an adherent film of fuel the thickness of which is determined by the relative positions of the parts [6 and 55. In this arrangement the two drums are preferably positively driven and it will be evident that the action of these two drums may be utilized as a preliminary step in reducing the thickness of the fuel film which may be further reduced to the finally desired thickness by means of a scraper acting on the drum l6.

Fig. 9 shows another arrangement wherein a fuel feeding belt 53 is mounted on two vertically spaced apart drums 5| and 52. Other conditions being equal, this arrangement will tend to feed a thinner film to the brushing member than a direct feeding arrangement since the fuel must be lifted vertically a greater distance on the belt than it would be on a drum.

Fig. 10 illustrates still another embodiment in which an endless bristle belt 55, running over rollers 54 and 56, is employed as a brushing memher in place of the brushing cylinder.

Fig. 11 illustrates another form of feeding arrangement wherein a regulated quantity of fuel is permitted to drop into a collecting channel El from which it flows through a horizontal slot-like opening onto a sloping surface 62 with which the brushing member is in contact. The fuel flowing in the form of a thin film on the surface 62 is atomized in the manner previously described by the action of the rapidly rotating brushing cylinder.

The brushing member need not necessarily be in the form of a brush i the more restricted sense of the word, since a y equivalent means may be employed. For example, as shown in Fig. 12, a drum 65 having flexible paddle-like arms 68 may be utilized. These arms, if employed, are preferably arranged spirally on the surface of the drum. In order to secure proper atomization with an arrangement of this sort, the drum must be driven at considerably higher speed than would be required for a brushing member provided with closely spaced bristles. The desired atomizing action might also be obtained with a so-called rag disc, or even thin metal blades arranged closely together on the feeding member and extending longitudinally thereof.

It is to be noted that in accordance with the present invention, substantial pressure contact between the brushing elements or bristles of the brushing member and the surface of the feeding member is not required for the purpose of effecting atomization. In the embodiment illustrated in Fig. 1, pressure contact is employed to produce the necessary frictional force required to rotate the feeding member, but it will be observed that in the form shown in Fig. 4, frictional contact between the brushing and feeding members is not required to drive the feeding member.

I have found that it is suflicient for purposes of effecting atomization, if the brushing elements simply make contact with the film of fuel on the feeding member without necessarily making contact with the feeding member itself. A sufficient degree of atomization is secured by the action of the bristles in breaking up the oil film and by the' action of centrifugal force in throwing the small particles of the broken up film off the bristles. Elastic deformation of the bristles due to contact with the feeding member and return of these bristles to their normal shape is not required to effect the desired degree of atomization.

This results, among other things, in long life of the brushing member even though the bristles are of relatively soft material as compared with the material of the drum since if any wear of the bristles occurs due to contact such wear is substantially terminated as soon as the bristles have worn to a point where they just clear the surface of the feeding member while at the same time extending through the film on the feeding surface.

In the form of apparatus shown in Fig. 4, the brushing member may advantageously be initially set to make light contact with the feeding drum and allowed to wear in so that a stabilized condition results which over long periods of time produces no appreciable wear of the atomizing parts.

I have further found that even where substantial pressure contact is exerted, as" in the form illustrated in Fig. 1, the rapidly rotating bristles of the brushing member are not subject to rapid wear even when softer than the surface of the feeding member, and experience with this form of apparatus has shown that even with relatively soft bristles, the feeding surface should be of quite hard material if premature wear of the feeding surface is to be avoided.

It will be understood that in the appended claims the term brushing member is not to be taken in a restricted sense, nor is the word rotary to be so interpreted, it being intended that the term brushing member include other than bristle brushes and that the term rotary member shall include such elements as the endless band brush illustrated in Fig. 10 and the endless band feeding member shown in Fig. 9. The term film is also understood to be inclusive of a layer of any suitable thickness for obtaining the desired degree of atomization.

It will further be understood that many variations may be made in the specific forms and arrangements of apparatus hereinbefore described by way of illustration, without departing from the invention, the scope of which is to be understood as embracing all forms of apparatus falling within the scope of the appended claims when they are construed as broadly as the state of the prior art permits.

What I claim is:

1. A liquid fuel burner having fuel feeding means including a rotary feeding member for feeding an adherent film of liquid fuel, a rotary brushing member positioned to contact said film of fuel, means for driving said brushing member to cause it to brush fuel from the place of contact directly into space in finely divided form appropriate for mixture with combustion air, means for supplying air to the finely divided fuel to form therewith a fuel-air mixture, and means for varying the speed of rotation of said feeding member independently of the speed of rotation of said brushing member to vary the rate at which fuel is brushed therefrom by said brushing memher.

'2. A liquid fuel burner having fuel feeding means including a rotary member for feeding an adherent film of liquid fuel, a rotary brushing member positioned to contact said rotary member, means for driving said brushing member to cause it to brush fuel from the place of contact directly into space in finely divided form appropriate for mixture with combustion air, the frictional contact between said members operating to rotate the rotary feeding member, and means for varying the contact pressure between said members, whereby to control the speed of rotation of said rotary member and the rate at which fuel is brushed therefrom by said brushing member.

3. In a fuel burner, housing structure having an outlet for a fuel-air mixture, means for producing a fiow of aig'through said outlet, means for forming a film of liquid fuel within said housing structure, a brushing member positioned within said housing structure to contact said fil'm of fuel, means for driving said brushing member to cause it to brush fuel in finely divided form directly from said film into the path of air flowing to said outlet, means for varying the rate at which said film of fuel is brought into contact with said brushing member independently of the rate of speed of the brushing member, and means for varying the rate of flow of air through said outlet.

4. Ina fuel burner, housing structure having an outlet for a fuel-air mixture, means for producing a flow of air through said outlet, means for forming a film of liquid fuel within said housing structure, a brushing member positioned Within said housing structure to contact said film of fuel, means for driving said brushing member to cause it to brush fuel in finely divided form directly from said film into the path of air flowing to said outlet, means for varying the rate at which said filmof fuel is brought intoc'ontact with said brushing member independently of the rate of speed of the brushing member and means for varying the rate of flow of air through'said outlet, the two last mentioned means being operatively interconnected to provide for increase or decrease of the quantity of said air upon increase or decrease of the quantity of fuel supplied to said brushing-member.

5. A liquid fuel burner including a movable feeding member providing a surface for feeding an adherent film of liquid fuel, a rotatable brushing member positioned to contact said film, housing structure enclosing said members, said housing structure having an inlet for air and an outlet for a fuel and air mixture, means for driving said brushing member to cause it to brush fuel from said surface in finely atomized state into the path of air admitted through said inlet and flowing to said outlet, means for controlling the admissionof air to said inlet, means for controlling the speed of movement of said feeding'me'mber, and automatic regulating means for simultaneously controlling the two last mentioned means independently of the speed of operation of said brushing member.

6. A variable capacity liquid fuel burner including a rotary brushing member, a rotary fuel feeding member arranged to carry an adherent film of liquid fuel into contact with said brushing member, means for driving said brushing member at high and substantially constant speed to cause it to brush the fuel from the feeding member directly into space in finely divided form appropriate for mixture with combustion air, means for supplying air to the burner to be mixed therein with said finely divided fuel to form afuelair mixture, and an adjustable variable speed driving connection from said driving means for rotating said fuel feeding member at different speeds to vary the capacity of the burner. I

7. A variable capacity liquid fuelburner including a' rotary brushing member, a rotary fuel feeding member arranged to carry an adherent film of liquid fuel into contact with said brushing member, means for driving said brushing member at high and substantially constant speed to cause it to brush the fuel from the feeding member directly into space in finely divided form appropriate for mixture with combustion air, means for supplying air to the burner to be mixed therein with saidfinely divided fuel to form a fuel air mixture, means for controlling the amount -of air supplied to the burner, an adjustable variable speed driving'connection from said driving means for rotating said fuel feeding member at different speeds to vary the capacity of the burner and means for varying said air controlling means in accordance with variations in the rate of speed of the fuel feeding member to provide predetermined relation of the ratio of fuel to air delivered by the burner at different capacities.

8. A liquid fuel burner including a housing providing a reservoir for fuel, a fuel feeding member mounted for rotation in said housing to be partially immersed in said fuel, a brushing member mounted for rotation in said housing and positioned to have an adherent film of fuel carried into brushing contact with it by rotation of the fuel feeding member, an outlet duct provided by said housing and located to receive finely divided fuel brushed from said fuel feeding member, means for forcing air into said housing to mix with the finely divided fuel and to deliver a fuel air mixture from said duct, and means providing a trap associated with said duct for retaining and returning to said reservoir unatomized liquid fuel collected on the walls of said duct.

9. A liquid fuel burner including a housing providing in its lower portion a reservoir for fuel, a fuel feeding member mounted for rotation in said housing above said reservoir to be partially immersed in the fuel therein, a brushing member mounted for rotation on said housing above said feeding member and positioned to have an adherent film of fuel carried into brushing contact with it by rotation of the fuel feeding member, a shaft for driving said brushing member, a fan driven by said shaft, said fan being located in a fan compartment in said housing, a connection between said fan compartment and the space in the housing in which the brushing member is located, means for controlling delivery of air from the fan through said connection, means for driving sai feeding member at different speeds to vary the rate at which fuel is carried to said brushing member, and a laterally extending outlet duct provided by said housing for delivery from the burner of a mixture of air and finely divided fuel brushed from said feeding member, the inlet of said outlet duct being located laterally of the line of contact between the fuel feeding member and the brushing member, and the walls of said outlet duct being upwardly inclined from the inlet to the outlet of the burner to provide for drainage from the outlet duct to said reservoir of unatomized liquid fuel collected on the walls of the outlet duct.

10. In a liquid fuel burner, a housing enclosing a reservoir for fuel, a brush chamber positioned above said reservoir, a mixing chamber laterally projecting and upwardly inclined with respect to said brush chamber, a brush mounted to rotate in said brush chamber, means for rotating said brush at relatively highspeed, an upwardly inclined outlet duct in the upper portion of said mixing chamber, a roller for transferring a film of fuel from said reservoir to said brush, said brush and said roller being arranged so that their adjacent peripheries are respectively movable in the same direction, said roller being mounted at a point below said brush and spaced therefrom adjacent said mixing chamber whereby the rotation of said brush may project fuel from said film in finely divided form directly into said mixing chamber toward said duct, and means for directing air into said mixing chamber and toward said duct.

KARL HENRIK LANGE.