US1771875A - Fuel atomizer - Google Patents

Description

` s. P. cowARDlN El' AL FUEL ATOMIZER Filed April s, 1924 fw s MW/min L y@ July 29, 1930.

aV//V/ l 6 Patented July-29, 19.3 i

SAMUEL P. COWBDIN' ANZI)v HARRY A cowAnDIN, or RICHMOND, VIRGINIA FUEL AroIgIZER Application med vApril s,

Our invention relates, in its mechanical aspecty to fuel atomizers vfor internal com'- bustion engines, heating furnaces, and for` vother purposes, in which oil and air under pressure are brought together and are so controlled that the oil is discharged in an atomized or highlycomminuted'state, and relates, in its method aspect, to the production of a fog-like fuel ingredient, specially intended I l0 as a combustible charge for explosive engines.v

One object of our invention is to provide an atomizer of simple and substantial construction and of few working parts, so arranged and operated that the fuel shallbe finely divided, and so that the loss of fuel-that is,

fuel passed through the atomizer without being finely dividedshall be reduced to a. minimum; and further' so that the quantity of air required for atomizationmay be regu-l lated and proportioned to the oil consumption and so that theatomized fuel discharged from the atomizer may be closely regulated to meetthe demands of fractional 'changes of load. l A further object of our invention is to control the direction of the discharge of atomized fuel from the atomizer.

In the conventional ty e of atomizer yfor atomizing liquid fuels with steam or with compressed air the liquid fuel is caused to 4issue from one orifice, While the steam or air is caused to issue under considerable pressure and at considerable velocity from another orifice, the stream of air or steam striking the stream of liquid fuel and reducing it to a more 0r less fine spray. In some of these atomizers there is loss of fuel, caused by the fuel dropping past the stream of air or steam before-it can be thoroughly broken up; and in` an attempt to minimize the fuelloss, an excess of air is used for atomization, which excess is an obstacle to regular ignition, and consequently to regular and satisfactory operation.. The arrangement and construction of our atomizer enable usto closely regulate both the oil and the air, or other atomizing agent, while proportioning the volume of air used to vthe vvolume of oil; and they enable us to practically eliminate waste of oil from drips. Even with air at comparatively low pressure, the oil-is finely and uniformly di- 1924. serial no. 703,972.

vided;l andits discharge `from the atomizer 1s under complete control. In the drawings which accompany and form a part of this specification, and in which like numerals refer to like parts in the several views: Figure I is a vertical section of the atomizer shown in position in the head of an internal combustion engine cylinder; Figure II is an enlarged view of the lower end of the atomizer shown in Figure I; Figure III is a partial vertical section showing .the control valves in an open pos1t1on; Figure IV -is a cross' section on line a-b in Figure II; Figures V and VI are details, broken, showing variations in thev shape of the discharge valve; and Figure VII 1s a detail, in vertical section, showing a vanation in form of the discharge end of the atomizer.

Referring to Figure I:- V1 representsl the cylinder head of an internal combustion eligine (Itrmay also be taken to represent the front. plate ofa furnace) 2 isthe body of the atomizer secured in the headaof the cylinder; 3 1s acap removably secured to the body 2, and forming with it'the rebate 4. On the cap 3 is fulcrumed a ta pet-lever 6, the head of which carries an adfustable' hammer 7- with. lock-nut 8. In the cap 3 is mounted the tappet-pin 9. x

' Securely clamped between the body of the atomizer and the cap 3 is a corrugated flexible diaphragm 10. This diaphragm may be of flexible material or of spring material. Pass-v Ingthrough and secured about the center of the diaphragm 10 is a valve-stem 1l, which is held in position relative to the diaphragm by the nut 12 and the lock-nut'13, The nut 12 is provided with slotted wings/14, engaging pins 15 set in thel body of the atomizer, to

hold the nut 12 from turning when the nut 13 `f is screwed down. rIhe tappet-pin rests upon the ylock-nut 13. Pressure upon this pin will depress the diaphragm 10 and the valve-stem 11. On the other hand: fluid pressure beneath the diaphragm 104 will tend to raise the valve-stem 11.

` Held securely in the bore 16 of the atomizerr A l body is the valve-stem sheath 17, which terrnnnates at its lower end inthe cone-shaped .ber 21 by chamber 21, which is closedby the discharge valve 22. 'This discharge valve may also be regardedas the air control valve, for it controls the admission of air to the mixing chamber 21, as well as the discharge of the atomized fuel therefrom. The discharge valve 22 and the oil valve 20 are connected by, and actuated by, the lower end 23 of the valvestem 11. The nut 24 is a means for holding the valve-stem in place while it is being adjusted; and it may be used to hold the discharge valve disc in place on the valve-stem in cases where the said disc is made as a separate part for the purposes of renewal or repair. It will now be seen that fluid pressure under the diaphragm 10 will hold the valves 20 and 22 against their seats.

The assembling of the oil valve and dis-' charge (alsopair regulating) valve on one and the same stem ensure ina verysimple way the synchronous and proportional opening of these valves; both important. considerations inthe economical use of fuel, and in the regularity of ignition andcombustion. j l

Formed within the cone-shaped seat 19 in the lower end of the atomizer body is an annular chamber 26, which is connected with the counterbore 27 in the upper part of the atomizer body by the duct 28; and which is also connected with the atomizing chamthe tangential tuyres or passages 29. See also Figure IV.

The diameter'of the valve-stem is reduced' at a point immediately above the valve 20 'to form an annular chamber 32; and this chamber is connected with the oil chamber 31 by the passage 33. V v l Air under pressure is admitted to the counterbore 27 by the inlet 34, and passes down the duct 28 to the chamber, 26. The air then enters the mixing chamber 21 at a high velocity by the tuyres 29, which are set tangentially to the mixing chamber. A whirling body of air is formed Within the mixing chamber by the air entering at the tuyres. Oil is admitted to the channel 35 and the chamber 31 by the inlet 36; and it then passes by the passage 33 to the chamber 32 above the oil valve 20. When the said oil valve is opened by moving the valve-stem 11, the valve 22 is also opened. Air enters the atomizing or mixing chamber 21 by the tuyres 29, atomizing the oil which enters the mixing chamber 21 in the form of an annulanfilm over the valve 20.. When used on an internal combustion engine, in which case ignition and `cornlulstion must be intermittent, the valvestem 11 is actuated by means of a tappet mechanism as shown at 6 and 9. Upon the valve-steam being actuated, the valve 22 opens, and immediately the pressure within the chamber 21 is momentarily relieved. At the same time the oil valve'20 opens, and a thin film of air enters the chamber 21 over the valve. This ilm of oil-is immediate-ly broken up by the high velocity streams of air entering tangentially to it by the tuyres 29; and the mixture of oil and air passes out of the open valve 22. Upon the pressure of the tappet being relieved, the air pressure under the diaphragm 10, which is larger in area than the combined areas of the two valves 20 and 22, closes the valves. It should be noted that` while the discharge valve 22 is closed, the oil valve 20 is also closed; and furthermore the air does not flow into the mixing chamber and through it, sinne its only outlet is by the valve 22. But the moment the valvestem is actuated to open the valves, the air within the mixing chamber is agitated; and into this agitated atmosphere there flows the thin film of oil. The fact that this iilm is in the form of a thin hollow cylinder, and the further fact that the agitated air strikes this film at a tangent, the mixture being further agitated during its passage through the 'mixing chamber, results in the production of a finely dividedcondition of the oil mixed with the air in the nature 'ofa fog-like I'uel ingredient, which mixture issues -from theI opening ofthe'valve 22. The form in which the oil fog issues from the valve 22 depends upon the shape of the valve opening. In our atomizer for-internal combustion engines we make ,the valve annular in shape as shown in the drawings. The oil fog then issues in the form of a sheet or veil radially to the valve. VIn furnace work we may use the same shape of,valve; or We may use an orifice valve, the valve itself seating on the inside of the orifice, as in the case oi' the needle valve of any liquid supply.

Reference has been made to the tappet motion for operating the atomizer. Such a motion is required only where the veil of atomized oil is to be released intermittently. In cases where the fog is to be released Acontinuously, as in most furnace work, 'a suitable form of adjusting screw or other device may be used in place of the tappet motion; the adjusting screw being caused to bear upon the valve-stem 11 vto operate the valves 20 and 22. The question of seepage of oil past an oil valve is not only one of loss; but in the case of an internal combustion engine seepage into aV cylinder results in loss of economy, irregularity in the richness of the mixture, and in some cases and under some conditions in preignition. An atomizer in which there is a seepage of oil is sometimes referred to as la past the valve it would also have to leak past the valve 22 before it could escape from` the chamber 21, and also by the fact that we use a balanced pressure between oil and air, or an air pressure exceeding that of the oil.` In either case the pressure of the air within the chamber 21 will prevent any seepage past the valve 20 even if that valve is in a leaky condition. The result of a higher air pres- `sure than oilpressure would not be to drive the oil back into the passage 33 andjpassage 31, for inthe case of an internal combustion engine the valve 22 is closed for a very brief space of time, and before the movement of the oil could be reserved the pressure in the chamber' has been relieved by the opening ofthe valve 22, and both oil and air have been injected into the chamber 21, and the oilfog into the cylinder of the engine. The question held back by the air pressure when the valve l .tric spark. The large volume of air of weeping is a serious matter in most atomizers', and particularly in those in which high oil and air pressures are used, and in which there is no balancing efect between the air and oil. Take an atomizer in which air pressures and oil pressures as high as eight hundred to a thousand'pounds per square inch are used,.and in"whichthere is no balancing effeet; the least irregularity of valve surfaces will 'allow seepagev of oil. If we used such' pressures in our atomizer, `the oil would be was closed.- Furthermore, if there was'a tend'- ency of the air at high pressure to leak ast avv discharge valve, this tendency vwoul pbe more than balanced by the upward air pressure under the diaphragmlG. The balancing eil'ect of the diaphragm 10 against the Vpres.v

sures 'on the oil and air valves results in a at high pressure isy employed-to atomize the f charge of oil. Reasons for the high air ,presa sure are that the cylinder compression. is high', that the oil must beI blown into this high compression at considerable speed vand also suliiciently atomized to ensure ignition, and

p that sometimes high velocity air is needed to j scour the -head of the piston to remove unburned oil. .High/velocityair andspray is a disadvantage in that-it is very difficult vif not practically impossible to re it with an elec- Per charge of loil lsmade necessary with that y 'I charge,-

atomizers referred to, there is used from sixteen to thirty times the volume of air we find it necessary to use in our atomizer for the same charge of oil. For this reason the fog discharged from our atomizer can be made much richer than the 'spray delivered from the types referred to above; and with our atomizer the refrigerating effect is very much less, for We use less air, and at a lower pressure.

I Thel richness or leanness of a mixture also has a bearing on cylinder pressures. A good mixture will iire by auto-ignition in an atmosphere at as low a pressure as lbs. per

mayvignite it, we shall have ignition. This' we accom lish with our atomizer, even though the load e low and the final fog-like mixture formed by the linely'atomized o il andthe air injected into thepcylinder is lean. For

lean mixtures when ignition is effected only by the heat of compression, a high `compression' is required. Therefore incases where large quantities of air-are used for atomization'or spraying, and at low loads, a high compression is required'to ensure auto-ignition. And again must we add `toth'ecomress ion.toovercomethefeffectsbf therefri much reducedload on the valve operatmg .p g

prove .the thermaleiciency ofthe engine,

`there 'isa limit to the net improvement, im-

osed by the cost ofcompressin'g the air'and y the'physical considerationsjto be met.

Wlth our atomizer we obtain-a quick dis- .and as rich a fog as desired, and in ay iin'ely divided state adapted to ensure ignition and' complete combustion. This fog is in jected into' the cylinder at any pressure which lwill carry the charge into the compression space' in the shorttime fired either by the heat of compression or by the. electric spark; and because We are able to `inject intothe cylinder a charge of `the fog-likeingredients termlned quality, we are able to time ignition to a nicety to obtain' the best results. At low loads and pressureswe can fire with certainty by the electric 's ark; and this feature, of our atomizer ena lesj us to start a cold engine from'a standstill, either forward or in reverse, without the aid of any compressed available; and it -is of certain and of predej t l llos, eratlon due toexpandmg alar'ge volume of air or other means for turning the engine over. A. few cubic inches of air for atomization,.a few charges of oil` (frequently only" one), and a spark, are what we require to start an engine. The reason for the variation of the 'number 4of charges of oil required isy one of engine or of fuel conditions. After an engine has been standing for some time,

the first shot in a cold cylinder may not fire as well as the second, and the resulting first fuel supply on again; and then to adjust theY spark until we get the first explosion. This method of starting is described in another application filed July 14,1924, Serial No. 725,931 -co-pending herewith. After starting, and as soon as compression rises to l2() lbs. or thereabouts, we can cut oi the spark and proceed to re by the heat of compression. We have found that an air pressure of about 200 lbs.is enough to get a suilici-ently rapid injection of oil fog into the cylinder when running, when the compression is vfrom 120 to 150 lbs.; and we carry a small reserve of air at, a somewhat, higher lpressure. for use in starting the engine, the excess pressure being to provide against possible leakage of air from the tank. In the caseof a thirty horse power boat engine we provide about thirty cubic inches ofair tank capacity; and when starting from a stand-still the reduction of pressure in this tank is often not more than from one to three per cent. After starting, air for atomization is supplied by a small air pump or compressor driven from the engine shaft.

We have found that with the conventional. type of orifice or valve-controlled outlet-the direction of the discharge of the nlm of fog in'a vertical direction is uncertain. The film is inclined tofollow the surface with which it is in Contact; or, von leaving a surface, it is inclined to follow an adjacent surface. 7lhis is particularly the case when the outside face of the opening or valve is a plain surface, cylindrical or otherwise. This is also the case with an oil ilni. When'discharged .from thev valve opening, the film of oil fog, if not controlled, may shoot upward or downward, over surfaces of cylinder head, cylinder walls; injector or atomizer surfaces; and the tendency of the film to deviate from a direct path will be influenced and varied by differences in conditions and pressures within the cylinder. "Where ignition is effected by the electric spark irregularity in the direction of the film discharge will result in irregular combustion and operation; and even when ignition is effected by the heat of compression orjby other means this irregularity *in the direction of the lm discharge will cause trouble. We control and direct the discharge of the film `of oil fog by providing a nf 37, as shown in Figures l, Il, III, V, Vl, and Vil of the drawings, on the periphery of the valve 22 or valve seat 38, or adjacent to the opening. `Whether the fin be made a part of the valve or of the valve seat; whether it be made a part of the wall of any form of opening; or whether it be supported independently of the valveor of the wall of the opening; the fin should terminate in an acute. edge, and its outside diameter must be greater than the outside diameter of the adjacent parts of the structure. The iilm of oil 'fog follows the surface of the valve opening and thesurface of the iin to its outermost edge,.and this edge it will leave without materially alteringits direction. The shape of the iin adects the direction of 'the discharge. A horizontal fin, as in Figure Vl, will give an approximately horizontal ilrn; and a fin shaped as in Figure V will give a slightly downward dis? charge.

When we desire to use electric ignition, tli'e direction of discharge of our oil fog film being controlled, we are able to adjust the position of our spark to the best advantage. Vve find that when an engine is started cold, orvwhen the engine is. idling, it is best that the film be directed through-the spark gap; that is to say, the sparkis adjusted so that it may envelop 'the film. Wc practically synchronize the spark and injection; 'though we allow adjustment between the two, as we find that under diderent starting conditions or running conditions a slightly diiferent adjustment may give the best results. Under .normal operating conditions, after starting we cut the spark off and ignite by the heat of compression. Then too the Jcontrolled direction lof the hlm results .in improved operation. Y y j In Vthe drawings the discharge opening formed between the valve 22 and its seat isA the end of the atomizer instead of on the i side as shown; in which case the valve is of the internal type (as in a' needle valve) instead of the external type. ln our furnace atomizers the discharge is continuous, and the opening and closing of the needle or outlet valve is controlled by a manually operated screw or similar mechanism. ln some classes of furnace work we also use the film-directing fin, disposed about the outlet opening, and shaped so as to guide the lm into the desired direction. l j A o From the foregoing description itwill be seen that one aspect ofour invention comprises a method of producing a fog-like ingrcdient for an explosive or combustible engine charge. And also that the steps of this method consist in introducing air under pressure into a chamber in a relatively smaller quantity than `the quantity of oil, both measured by Weight; in'intermittently introducing fuel oil'by pressure into such chamber in a relatively larger quantity than the quantity of the air, so measured; in intermittently opening the discharge end of such chamber, as when the oil is admitted into the inlet end, to cause the pressure on the air to put 1t into violent motionv and by such motion to cause it to so atomize the oil that when thus mixed With the air a fog-like fuel ingredient will result.

And it will be understood also that by preference the air is introduced into such chainber from the air passage in a tangential direction with reference to the wall of the chamber so as to enhance or create a whirling motion of the air. And again, that by preference also the oil is admitted to'said chamber in a film-like formation which. with such whirling motion of the air, vresults in the more perfect and almost infinitesimal breaking up ofthe oil so that' when these minute particles are taken up by the air the aforesaid fog-like product results.

We have referred above to using about 200 pounds air pressureto eiectinjection when the compression is about 120 to 150 pounds. We desire to state further that we usually use an air pressure for the atomzer ranging from 120 to 400 pounds, which is suiiicient, on the meeting of the oil and air in the mixing or atomizing chamber 21, the air entering such chamber through the tangential tuyres 29. These tangential streams of air act violently to break up and atomize the oil and to cause the line particles to become suspended as 1t were, 1n the a1r. -The pressure of the air and the oil, each at say 150 to 400 pounds per square inch, and the whirling course of the air, both entering the mixing or atomizing chamber 21, and the rapid passage of the oil and air -past the discharge valve or disk 22 -combine in their action to' reduce the oil particles to such a state of entire atomization as is distinguishable only from a state of vapor or vaporization. which latter state does not occur until this fuel ingredient is subjected to the heatincident to combustion or that fimmediately preceding ignition. bestillust-ration We can give of the state of the fuel charge, as it issues from this atomzer` and enters a cylinder, is that the charge cnnstitutes a fog made up of the constituents of oil and air. v

It is further to lbe understood that the'fo'g produced by this atomizer is composed of a less quantity of air than ofoil. This refers to the relative quantities as determined by The weight. For instance, taking one cubic foot of free air per brake horse-power (which is conservatively high) and .6 of a pound of oil per brake horse-power per hour (which is about the amount used) the Weight'of such quantity of air will be about .075 pounds per brake horse-power per hour. This is on the assumption that We have free air at about 'TO degrees F.

IVe claim:

l. An atomzer consisting of a body having an air inlet passage for air under pressure leading through the body, an atomizing chamber near the discharge end of the structure," tangential tuyres connecting the air passage with said chamber, an oil passage extending through the body for oil under pressure, a valve stem extending through the sov structure and adapted to be actuated from the y outside, and two valves carried by said stem. one to open communication between the oil passage andthe atomizing chamber and the other to permit the oiland air fog generated in the atomizing chamber to escape, such fog 2. In an atomzer comprising an oil chamber and a mixing chamber, means in a con- 9;,

dition for continuously delivering oil to the oil chamber, pressure means in a condition for constant-ly delivering air under pressure to said mixing chamber, and a provision for causing the air to Whirl' in said chamber, and a common means for admitting the oil to the mixing chamber and discharging the mixture of oil and air, now fog, from the mixing chamber.

' 3.A In an atomzer comprising an oil chamber and a mixing chamber, pressuremeans in a condition for continuously delivering oil under pressure to the oil chamber, pressure meansin a condition for constantly deliveringair under pressure to said mixing chamber, and 4tangential tuyres for directing said air into said mixing chamber, and a common valve means for admitting the oil to themixing chamber and discharging the mixture of lojil and air, now fog, from the mixing chamer. 4. In an atomizer comprisingl a mixing chamber, means in a condition constantly delivering airr to said mixing chamber tangentially, and means lfor periodically admitting oil in a thin sheet like form to Isaid chamber across the pathl of the entering'air, and for discharging the mixture of oil and air. now fog, from said chamber.

In testimony whereof we hereunto atlixour lll)

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