US2976921A - Oil burners - Google Patents

Description

March 28, 1961 L. MoTLEY 2,976,921

OIL BURNERS Filed April 4, 1957 2 sheets-sheet 1 @Awww March 28, 1961 L. MoTLl-:Y 2,976,921

^ OIL BURNERS Filed April 4, 1957 2 Sheets-Sheet 2 FIG.2

rroRA/srs on. sUnNnns Lewis Motley, Wenlock Abbey, Much Wenlock, England, assignor to Redheugh Iron & Steel Company Limited, Durham, England, a British company I Filed Apr. 4, 1957, Ser. No. 650,629 claims priority, application Great Britain Apr. 6, 1956 s claims. (cl. 158-77) This invention relates to oil burners and particularly to oil burners of the rotary atomising type in which a rotary atomising cup is mounted fast on the end o-f a hollow driving shaft through which oil to said cup is fed. in burners of this type the oil in the cup forms itself by centrifugal force into a lm on the inner periphery of the cup and this' lrn is yatomised as it leaves the end of the cup. I have found that, for good atomisation it is essential that the cup shall be accurately coaxial with the hollow driving shaft in order to ensure that the thickness of the film shall be uniform.

It is one object of the present invention to provide an oil burner of the rotary atomising type in which it'is ensured that the cup shall be accurately coaxial with.

the driving shaft.

Another object is the provision of an oil burner of the said type in which dripping from the cup during shutV down periods will be prevented, and in which'itwill be` possible to spin the oil in the shaft without admitting. it to the atomising cup, thereby preventing waves in the cup film during starting, and making it possible to circulate the hot oil without using the burner.

Other objects and advantages will appear hereinafter.`

The invention comprises an oil burner of the rotary atomising type in which a rotary atomising cup is mounted fast on the forward end of a hollow driving shaft through which oil to said cup is fed, wherein the mounting of said atomising cup fastvon the forward end of said shaft is effected by said forward end Vof said shaft and therear end of said cup being formed ,co-axially with complementary conical surfaces, and said cup and shaft being heldcoaxially together with said conical sur-KV faces in engagement.

The inventionfurther comprisesan oil burneriof ,theV

rotary atomising type in which a rotary atomising cup is mounted fast on the forward end of a hollow driving, shaft through which oil to said cup Vis fed,V wherein irn-A mediately behind said cup, a cut-offvalve is providedA said burner mainly in yseicato'rnising type, "That is to say it comprises a rotary atomising cup 1 mounted fast on the end of a hollow driving shaft 2 thro-ugh which the oil to said cup is fed. Said atomising cup 1 consists essentially of a tubular member which forms a continuation of said hollow driving shaft and has an internal diameterfwhich increases from its inlet to its outlet end. A fan 3 is mounted fast on the .driving shaft-atomisingcup assembly, at about theA point of junction' of said driving shaft and atomising cup. Said fan 3 has a fixed fan casing 4 and it operates to suck air into the casing through a series of openings 5 in the back thereof fairly close to the root ends of the fan blades. Said air is guided by the casing 4 to flow radially outwards past the outer extremity of the fan blades and then radially inwards on the front side of the fan, whereafter it is guided by an extension 6 of the fan casing on a smooth curve longitudinally forwards to be ejected to atmosphere through a narrow annular opening 7 around the forward end of the atomising cup 1. The oil, as it iiows along the inside of the atomising cup 1 is thrown by centrifugal force against the inner surface of said atomising cup, where it is flattened into a film, and, as it leaves the forward or outlet end of said cup it is caught by the annular stream of air projected from the annular opening 7 and forms therewith a highly inflammable atomised mixture. i

In the present arrangement a fuel out-olil valve 8 is placed within the hollow driving shaft 2 immediately behind the atomising cup 1 and in this way the common disadvantage, that free oil from said hollow shaft drips from the cup during shut down periods, thereby causing carbonization, is obviated. The said valve 8 is adapted to rotate with the shaft 2 and` it moves longitudinally of said shaft between a forward closed position (as illustrated) and a rear open position. For thus moving said valve, the same is connected by means of a connection 8a to the forward end of an actuating rod 9 which extends longitudinally through the hollow shaft 2V and projects out of the rear end of the latter into a closed space 10 in the casing of the burner through which passes the oil to said hollow shaft. At its rear end said actuating rod 9 is connected, by means of a running connection 1l, to one arm of a bell crank lever 12 pivoted at 13 whose other arm is connected to a vertical rod 14. Said vertical rod passes upwards through a hole in the magnetic plunger 15 of a solenoid 16. When the Ksolenoid 16 is energized the plunger 15 is lifted and strikes a head 17 on thev top of said vertical rod 14, thereby lifting the latter and, through the bell crank lever 12 pulling the actuating rod 9 and valve 8 to the valve-open position. When the solenoid 16 is dre-energized, the plunger 15 and rod 14 fall and the valve S is returned to its closed position. The space in which :the solenoid plunger reciprocates is closed to the atmosphere and may be in fluid communication with the aforesaid closed space 10 Vat the rear end of the hollow shaft. Said actuating rod 9 consists of a metal strip twisted about its longitudinal axis so that its two edges are helical. Said two edges engage the inner surface of the bore of the hollow shaft 2 and when the hollow shaft is rotated, it

` position.

is the friction between said inner surface and said edges which causes said actuating rod 9 and valve to rotate with it. Each time said hollow shaft 2 commences to rotate there will be a time lag before the actuating rod 9 catches up with it. Duringfthis time lag the helical edges of said actuating rod 9 will scrape against the inner surface of the bore of the hollow shaft 2 thereby scraping off any dirt or carbonized oil deposited on said inner surface so that the same will be swept away by the oil ilow through said bore. v

Said valve 8 has a conical forward surface which engagesl acorresponding conical seat to establish the closed This conical seat is formed on the rear end of a short tubular member 18 screwed into the forward end portionof the bore hole of the hollow shaft 2, which forward end portion is of greater diameter than the remainder.` This short tubular member 18 has a forward extension 19 of reduced diameter which extends into the rear end of the cup 1 and the forward end thereof is closed'except for a hole which forms abearing fora thin V rod 2li which 'isintegral with'the valvej 8' and projects ICC Patented vMar. 28, 1961];

shut-down periods, and, more important, makes it possible to spin the oil in the shaft without admitting it to the cup. In practice, when starting, the oil is spun in the shaft for a period without admitting it to the cup and thus it forms a uniform filmvround the bore of the shaft, and when the valve 8 is opened a uniform film is formed around the inner periphery of the cup substantially from p the beginning, and the burner will ignite correctly Afrom the beginning, no waves or irregularities being formed in the film in the cup. I

For connecting the atomising cup 1 to the forward end of the hollow driving shaft 2, the rear end of said atomisin'g cup is formed with a male conical surface and the forward end of said hollow drivingshaft is formed `with a conical female surface and the two parts are drawn axially together so that the cones engage at 22. For drawing said two parts together, the atomising cup l has a circumferential groove formed on its outer surface just in front ofits rear conical surface and a circlip23 is sprung into this groove. The Vouter surface` of `the hollow driving shaft 2 is formed with a shoulder facing rearwardly and a bored boss Z4 whose bore at its rear end Vhas` a shoulder facing forwardly is slid on said driving shaft from therear end so that its said forwardly facing shoulder engageskthe rearwardly facing shoulder on said shaft at 25. At this position the forward end of the boss 24 ,overhangsl the circlip V23. A thrust ring 26 which is loose on theatomising cup 1 ts, at its rear end, inthe forward end of the boss Z4 and abuts against the circlip 23 and finally a nut 27 is screwed on to the forward end of the boss 24 which nut has la rearwardly facing shoulder which engages at 28 a forwardly facing shoulder on said thrust ring 26. It will be seen that when said nut 27 is tightened said nut, said ring 26 and said circlip 23 aremoved rearwards Yrelative to said boss 2d, so that the atomising cup 1 is forced rearwardly relative to said driving shaft 2 and the conical surfaces at 22 are forced into engagement. By securing the cup 1 to the shaft 2 in this way it is ensured that the cup and shaft shall be accurately coaxial with the result that good atomisation is obtained as heretofore described.

The taper angle is selected so that the cup ll and shaft 2 do not stick but can be readily separated upon unscrewing the nut 27. Y

Said boss 24 also forms the means for mounting the fan 3 on the shaft-cup assembly. The said boss 24 is formed with a ange 29 in a radial plane about mid way of its length and the fan 3 is bolted by means of bolts 30 to this flange.

:The system employed is wthat in which oil from a main tank is continuousiy sucked by means of a line pump and delivered into a reservoir from which it flows back to said main tank, and some of the oil in Vsaid reservoir is continuously pumped to the space 10 and then to the burner proper by means of a metering pump. in the present arrangement the line pump and the metering pump are both enclosed in Ia common casing 33 which also encloses the hollow shaft 2, and 4is in one unit structure with the fan casing and the extension 6.

For rotating the hollow driving shaft 2 an electric motor 4'? is mounted above said hollow shaft with its spindle parallel thereto and a pulley 48 on the spindle of vsaid electric motor is coupled to a pulley 49 on said hollen7 shaft by means of V belts 50. An intermediate part of said hollow shaft is formed externally with a worm f and this is in driving relationship with a worm wheel 52 immediately beneath it by which worm wheel the aforesaid line pump and metering pump are driven. The electric motor 47 is mounted on the top ofthe casing 33, arid'th'efcasing Vis givenV a re-entrant form so that a small 4 portion of the driving shaft 2 near its rear end is outside the casing. The pulley 49 by which the motor drives the driving shaft is mounted on 'this small portion of said shaft.

The casing 33 is divided into compartments one of which forms the aforesaid closed space lil at the rear end of the driving shaft.

I claim:

1. An oil burner of the rotary atomizing type comprising an atomizing cup having an external annular groove, a rotary hollow drive shaft for supplying a fuel to said cup with the fuel in direct contact with the bore of said shaft, mounting means securing said cup coaxially to the forward end of said shaft for joint rotation of said cupwith said shaft, said mounting means including complementary smooth conical surfaces formed at the rear end of said cup and the forward end of said shaft colaxially with the longitudinal cup axis respectively, a shoulder on said drive shaft, a resilient split ring sprung into the annular groove around said cup, a thrust ring surrounding said cup and engaging the side of said split ring remote from said shoulder, two clamping parts respectively surrounding said shaft and said cup, screw means drawing said clamping parts towards each other, whereby said clamping parts respectively press against said thrust ring and said shoulder and draw said conical surfaces into tight engagement with each other, thereby securing said cup and said shaft coaxially with the shaft axis, and a fan mounted fast on one of said clamping parts.

2. An oil burner of the rotary atomizing type, comprising an atomizing cup, a rotary hollow shaft for supplying'fuel to said cup, means mounting said cup coaxially on the forward end of said shaft for joint rotation of said shaft, a valveV seat mounted in the bore of said shaft, a complementary cut-off valve mounted in the bore of said shaft and longitudinally slidable relative to said seat for selectively cutting oil off and admitting it to said cup, said valve vbeing rotatable together with said shaft and cup, an actuating member having a forward end and a rear end, said'actuating member being coupled at its forward end to said valve and extending at its rear 'end to the rear end of `said shaft, said actuating member being rotatable with said valve, and operating means external to said shaftand connected, through a running joint, to the rear end of said actuating member, for longitudinally moving said actuating member and valve, said actuating member including an inertial structure having longitudinally extending edge portions in frictional engagement with the inner periphery of said drive shaft whereby, at starting, said actuating member lags behind said drive shaft and said inner periphery is scraped and i thereby cleaned by said actuating member.

lus

3. A burner according to claim 2, wherein said actuating member comprises a metal strip twisted so that its two edges are helical, and said edges engage the inner periphery of said drive shaft.

References Cited in the file of this patent UNITED STATES PATENTS Great lBritain Apr. 13, 19.28

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