US2566532A - Combustion spray nozzle - Google Patents

Description

Sept. 4, 1951 E. o. oLsoN COMBUSTION SPRAY NOZZLE Filed Aug. 20, 1947 Patented Sept. 4, 1951 COMBUSTION SPRAY N OZZLE Eugene 0. Olson, Des Moines, Iowa, assigner to Delavan Manufacturing Company, Des Moines, Iowa, a corporation of Iowa Application August 20, 1947, serial No. 769,661

4 Claims.

The present application relates to combustion spray nozzles of the type used for combustion engines, and particularly to an improvement for effecting more eflicient operation of the nozzles.

The general type of nozzle to which the present invention is applied is one in which fuel is supplied to the nozzle under pressure and only a portion thereof enters the combustion space desired, the remaining being withdrawn through a by-pass channel and returned to the source of fuel supply. The purpose of such an arrangement is to accomplish flow of fuel into the combustion space with some independence from the feed line pressure in order. that the flow-pressure characteristic can be made to conform to a straight line graph or otherwise varied as desired. Without the provision of such by-pass feature, the iiow of fuel into the combustion space is approximately proportional to the. square root of the pressure applied.

For the purposes of explaining the effectiveness of the present invention a brief statement of the operation of such nozzles is here given. Fuel is supplied under pressure to a swirl chamber through tangential passages. The fuel entering the swirl chamber swirls around the periphery thereof and passes into the combustion chamber through a nozzle orice which is disposed axially of the swirl chamber. The by-pass channel leads from the swirl chamber axially thereof and from a position opposite the nozzle orifice. A hollow vortex forms in the swirl chamber and, by withdrawing fuel from the swirl chamber through the ley-pass channel,Y in instances where the present invention has not been applied, air from the hollow vortex is withdrawn with the by-passed fuel, and interferes with proper operation of the fuel nozzle when the bypassed fuel is returned to thesource. of supply.

An object of the present invention is, therefore, the provision of means to. prevent thewithdrawal of air from the swirl chamber through the by-pass channel.

Another. object is the provision of such means whichcan be inserted in a standard nozzlei without the necessity of re-designing the nozzle.

Stillanother object is the'provision of such a means which is simpleand economical inimanufacture as well as being easily placed in the nozzle.

With these and other objects. in View, myinvention consists in the construction, arrange'- ment, and combination of the various partsofmy device whereby the objects contemplated are attained, las hereinafter more fully setiforth; pointed out in my claims, and illustratedini the accom,- panying drawings, wherein.:

Figure 1 is an axial, sectional View through a spray nozzle illustrating the application of my invention thereto;

Figure 2 is a sectional view taken on line 2-2 of Figure 1; and v Figure 3 is a sectional View taken on line 3--3 of Figure 1; and

Figure 4 is an enlarged view of that portion enclosed in dot-dash lines at the left in Figure 1.

Referring in detail to the drawings, Figure 1 includes an adaptor I2, which, for convenience, will also be referred to as a nozzle block and may be formed of any metal commonly used in nozzles. The adaptor or nozzle block I2 is preferably polygonal in cross-section for convenience in applying it in an installation. The nozzle block I2 is provided with a bore i3 formed in the rear thereof eccentric to the axis which is adapted for attaching by soldering, brazing or screwing a pipe or lead ill for the flow of fuel under pressure from a convenient source (not shown), into the bore I3 and through the nozzle assembly. Ahead of the bore I3 and communicating therewithis a reduced bore I5 leading to and communieating with a circular space or cavity I6 which, in the iinal nozzle assembly, becomes an annular space. Ahead. of the space I6 is a threaded opening I'I of a diameter less than the space I6 and interiorly threaded to receive the nozzle proper.

The adaptor or nozzle block I2 is provided. with an axialbore i8 for the reception by means of a press t of a pipe I9 which forms a return conduit to the source of fuel. A reduced bore 2li leads inwardly from the bore i8 and communicates with the space I6 and opening El. An annular seat 2l surrounds the inner end of the bore 2i?.

The nozzle proper includes a nozzle body 2-'i having a central portion 26 which may also be polygonal in cross-section, and a rearward reduced portion 28 exteriorly threaded and adapted to be threaded into the threaded opening Il. A shoulder 6i! is formed on the rear face of the central portion 2S for seating against the front face of the nozzle block i2 around the threaded opening Il. Ahead of the central-portion E@ is a tapered front portion 32. The whole nozzle body 24 has a central bore, the main portion of which is indicated at 34 and extends to the rear of the nozzle Ibody 24 where it communicates with the space I6. The rear portion of the bore 34 is threaded as indicated at 35. The forward end of the bore 34 has a reduced portion 38 terminating` in a still further reduced portion vlll). A tapered shoulder 132 is formed between the reduced portion 3.8. and the rear main portion of the bore 34.

An insert or nib 44 is press fitted into the portion 38 of the bore 34, and has an extension fitted in the portion 42 of the bore, the front face of the nib being substantially ush with the front face of the front portion 32 of the nozzle body. The nib 44 is provided with an axial orifice 46 having a central cylindrical portion, a diverging outlet 48 and a rearward diverging surface 50 from which leads another diverging surface 52.'

The diverging surface 52 is of wide angle conical formation and terminates at a point slightly short of the shoulder 42.

A distributor indicated as a Whole at 54 is inserted in the bore 34 of the nozzle body 24. distributor 54 includes a head portion 55 having a truncated, conical front surface 58 in which are provided a plurality of slots or channels 69. 'lhe slots 6i] lead from the space around the head 55 in the bore 34 to points adjacent the diverging surface B in the nib 44. The center of the front face 58 of the head 5 is flattened as indicated at 62 and forms with the conical surface 59 a swirl chamber 64. tangentially with respect to the true radius of the head 55, as will be evident from Figure 3. It will be noted that the slots S6 form substantially a continuation of the shoulder 42, leading from the bore 34 to the swirl chamber 54.

Centrally of the distributor 54 is an enlargement 56 having exterior threads for securing the distributor in the threaded interior of the bore 34. The enlargement 55 is provided with a y plurality of openings S8 disposed substantially parallel with the axis of the device. Rearwardly of the enlargement 56 of the distributor 54 is a reduced end 'i9 forming a shoulder f2. The distributor 54 is provided with a passage i4 communicating axially with the swirl chamber 64. A passage 'I6 formed in the distributor communicates with the passage '14, extends through the distributor 54, and communicates with the bore 20. Sealing means 82 is interposed between the shoulder 'l2 and the annular seat 2 I.

The following passages together form a by-pass channel, namely, I4, n, 29, and I8, which lead directly from the swirl chamber 64 to the return conduit I9, and the means for returning the bypassed fuel to the source of supply.

An interceptor plug 8E is interposed in the bypass channel by inserting it in the bore 29 between the reduced end 'I0 of the distributor 54, and the inner end of the pipe I9. The interceptor plug 39 is in the form of a disk having substantial thickness in axial direction and, as viewed in Figure 2, is provided with a plurality of openings 95 formed around the periphery thereof. In the preferred forni of the interceptor plug 88, the openings 90 are three in number and disposed at the periphery of the disk, although other positions may be desired on occasion, and a different number may be preferred. The total net cross The The slots Si] are disposed sectional area of the openings 99 is less than the cross sectional area of the passage I4.

The interceptor plug 88 is inserted in the bore 78 by means of a press fit securement and the nozzle assembly is otherwise a standard article of production whereby it will be seen that the nozzle assembly does not need to be re-designed for the inclusion of the interceptor plug 89.

Operation Fuel under pressure is supplied by any conthe slots 60 into the swirl chamber 64. The tangential disposition of the slots 60 produces a swirling action of the fuel whereby, by centrifugal force, it follows the periphery of the swirl chamber. The quantity or mass of fuel in the swirl chamber is indicated at 92 in Figure 4. In the swirling motion of a quantity. of fuel, such as here described, the Velocity of the liquid increases toward the center of the swirl chamber, i. e., it varies inversely as the distance from the center of rotation. Also, at any point of the radius of the swirl chamber, the mathematical product of the velocity times the pressure is constant, or substantially so, except for friction losses. Since the velocity increases toward the center, the pressure must decrease and, at a certain point, the pressure at the center may reach a minus quantity. In such a condition, air enters the oriiice of the nozzle to fill the vacuum and forms a hollow vortex. Such a hollow vortex is illustrated at 94 in Figure 4.

Considerably more fuel is injected or forced through the nozzle assembly than is intended to be used in the combustion space. The by-pass channel is utilized for withdrawing that portion of the fuel from the nozzle assembly which is not intended to be used in combustion. By retaining constant the pressure forcing the fuel through the nozzle, and varying the withdrawal of 'fuel through the by-pass channel, the amount of fuel emerging from the orifice of the nozzle into the combustion space can be regulated in constant ratio to the quantity of fuel Withdrawn through the by-pass channel. This arrangement is in contrast with other types of fuel nozzles in which the fuel emerging from the orifice is in proportion to the square root of the pressure applied.

Heretofore and before the present invention, when fuel was withdrawn through the by-pass channel, a portion of the fuel indicated at 92 was drawn through the passage 'I4 in the head 56 of the distributor 54. When a considerable quantity of fuel was so withdrawn, the wall of fuel 92 covering the passage 14 became depleted, and the air from the hollow vortex 94 passed into the by-pass channel and interfered with the desired procedure of directly returning the bypassed fuel into the source of supply. When such air was permitted to enter the by-pass duct I9, it caused operating difculties by being ultimately conveyed to the fuel pump, where it collected, impairing the functioning of the pump, and also by being conveyed into the fuel supply line where it interfered withl the precise control of fuel ow rate and positive shut olf.

In the present instance, the interceptor plug 38 prevents the passage of air from the hollow vortex 94 into the by-pass channel. The openings 90 in the interceptor plug 88 are of less total cross-sectional area than the cross-sectional area of the passage 'I4 and, of course, less than the cross-sectional area of the passage l5. This restriction amounts to a temporary obstacle in the flow of fuel'through the by-pass channel and produces a backing-up pressure through the passage 16 and into the' passage Ill and exerting itself at the point of communication between the venient means through the pipe I4 from which it passes through various passages, such as bore I5, space I6, bore 34, holes 68, and finally through passage 'I4 and Ythe swirl chamber 54. This backing-up pressure prevents the emergence of air from the hollow vortex 94 into the by-pass channel. However, the effect of this backing-up pressure upon the rate of fluid discharge from the nozzles orifice 45 is negligible because an increase in fluid pressure L at the center of the by-pass opening 14 does not produce an equal increase in pressure at the periphery of the discharge orice 46.

When fuel is drawn through the openings 9U in the interceptor plug 88 it is replaced by additional fuel drawn from the swirl chamber 64 through the passage 14. Therefore, fuel flows through the by-pass channel as freely as desired, while sufficient pressure is retained between the interceptor plug 88 and the swirl chamber 64 to prevent the passage of air into the by-pass channel.

It will be seen from the foregoing that an efflcient and effective device has been produced for accomplishing the purposes of the invention and overcoming objections to previous types of nozzles, namely, to prevent the passage of air into, and admixture with, by-passed fuel being withdrawn from the nozzle and returned to the source of supply, or to the fuel pump inlet.

While I have herein shown and described a preferred embodiment of my invention, manifestly it is susceptible of modication and rearrangement of the parts without departing from the spirit and scope thereof. I do not, therefore, wish to be understood as limiting my invention to the precise form herein disclosed, except as I i may be so limited by the appended claims.

I claim as my invention:

1. In a combustion spray nozzle having a nozzle block, an inlet channel formed in said block, a nozzle body secured in said block, said body having a swirl chamber formed therein, tangential passages communicating between said lnlet channel and swirl chamber, an axial nozzle outlet from said swir1 chamber, a by-pass bore formed in said nozzle block, a by-pass channel formed in said nozzle body leading axially from said swirl chamber and communicating with said by-pass bore, said by-pass channel being of less cross-sectional area than the cross-sectional area of said by-pass bore, the improvement comprising an interceptor plug secured in said by-pass bore at a point remote from said by-pass channel, said interceptor therein of less cross-sectional area than said bypass channel.

2. In a combustion spray nozzle having a fuel supply inlet channel therein, a swirl chamber in communication with said inlet channel, tangential passages communicating between said inlet channel and said swirl chamber, a nozzle outlet from said swirl chamber, and an axial bypass channel leading from said swirl chamber, said by-pass channel having a portion of reduced cross-sectional area communicating with said swirl chamber, the improvement comprising an interceptor plug secured in said by-pass channel at a point remote from said reduced portion, said interceptor plug having an opening therethrough, said opening being of less cross-sectional area than the cross-sectional area of said reduced portion of said by-pass channel.

3. A combustion spray nozzle comprising, in combination, a nozzle assembly having a conical swirl chamber, said swirl chamber thereby hav-- plug having an opening ing a small-diameter end and a large-diameter end, a nozzle outlet leading axially and centrally from the swirl chamber through the small-diameter end thereof, an inlet channel entering tangentially into said swir1 chamber and adapted for now of fuel therethrough into the swirl chamber in a swirling motion, said swirling motion tending to produce a hollow vortex in said swirl chamber, a single by-pass channel leading axially and centrally from the swirl chamber through the large-diameter end thereof and adapted for the withdrawal therethrough of fuel from the swirl chamber, and an interceptor plug in said by-pass channel at a point remote from the point of communication of the by-pass channel with the swirl chamber, said interceptor plug having openings therethrough of less total cross-sectional area than the cross-sectional area of the by-pass channel at its point of communication with the swirl chamber.

4. A combustion spray nozzle comprising, in combination, a nozzle assembly having a conical swirl chamber, said swirl chamber thereby having a small-diameter end and a large-diameter end, a nozzle outlet leading axially and centrally from the swirl chamber through the small-diameter end thereof, an inlet channel entering tangentially into said swirl chamber and adapted for flow of fuel therethrough into the swirl chamber in a swirling motion, said swirling motion tending to produce a hollow vortex in said swirl chamber, a single by-pass channel leading axially and centrally from the swirl chamber through the large-diameter end thereof and adapted for the withdrawal therethrough of fuel from the swirl chamber, said by-pass channel having a portion of reduced cross-sectional area communicating with the swirl chamber, and a portion of enlarged cross-sectional area posterior to said reduced portion with respect to the flow of fuel therethrough, and an interceptor plug in said enlarged portion at a point remote from said reduced portion, said interceptor plug having openings therethrough of less total crosssectional area than the cross-sectional area of said reduced portion of the by-pass channel.

EUGENE O. OLSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 625,466 Randolph May 23, 1899 748,971 Millspaugh Jan. 5, 1904 1,326,488 Fisher Dec. 30, 1919 1,620,209 Ihne Mar. 8,'1927 2,037,645 Vroom et al Apr. 14, 1936 2,079,430 Bargeboer May 4, 1937 2,315,172 Voorheis Mar. 30, 1943 2,323,001 Bargeboer June 29, 1943 2,345,402 Lubbock et al Mar. 28, 1944 2,373,707 vPeabody Apr. 17,` 1945 2,374,041 Saha Apr. 17, 1945

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