US2579004A - Liquid fuel burner with nondribble tip valve - Google Patents

Description

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John Ruskin Jogce W Wflfi/W his Afiorneg Patented Dec. 18, 1951 LIQUID FUEL BURNER WITH NONDRIBBLE TIP VALVE John Ruskin Joyce, London, England, assignor to Shell Development Company, San Francisco, Calii., a corporation of Delaware Application September 17, 1948, Serial No. 49,732 In Great Britain September 24, 1947 Claims. 1

This invention relates to liquid fuel burners having a pressure atomizing nozzle of the forced vortex type provided with swirling ports or grooves through which liquid fuel passes into a vortex chamber, and having a spill return line for the return of liquid fuel from the vortex chamber to 'a fuel reservoir, and either a spill control for the spill return line or a control to vary number or size, i. e., the effective area of the swirling ports or grooves, and, thus, the quantity of fuel delivered to the vortex chamber, or both of such controls. More particularly, the invention relates to improvements in liquid fuel burners of the general type disclosed in British Patent Specification No. 536,331. For the sake of brevity, the term "swirling port" will hereinafter be given generic connotation to include ports, grooves or ducts, at whatever cross-sectional shape, arranged for supplying fuel into a swirl or vortex chamber in a direction to cause the fuel to swirl or form a vortex.

In burners of this general type provision is made for supplying to the vortex chamber a quantity of fuel in excess of that which is discharged through the final orifice, such excess fuel being returned through a spill return line. Such burners facilitate operation over a wider range of rates of discharge through the final orifice within a limited range of fuel supply pressures by regulation of the back pressure in the spill return line.

One of the difficulties experienced with burners of the mentioned type when handling heavy fuel oils, such as bunker oils and the like, which are solid or extremely viscous at normal temperatures and have, consequently, to be heated prior to use, lies in the tendency during periods of shutdown for the oil remaining in the burner to solidify. Under such circumstances, on starting up the burner a pastylike ribbon of semi-solidified oil is injected into the combustion chamber, which cannot be ignited by the normal ignition means employed and, consequently, fouls the interior of the combustion chamber. When eventually the hot oil reaches the burner and is atomized and ignited, the viscous mass of cold oil, previously exuded into the combustion chamber, burns with consequent fouling of the chamber by coking.

It is therefore desirable when burning heavy fuel oils to flush the interior of the burner with hot oil right down to the vortex chamber before the burner is opened up. Such pre-circulation is in many cases also advantageous when burning lighter fuels. Thus, for example, where a combustion chamber is provided with a plurality 2 of burners, some of which may be shut ofi under conditions of light load, cold fuel circulated through the burners so shut off acts as a cooling agent, protecting the burners from the risk of damage by heat from the flame of other burners remaining in operation. Pre-circulation of the fuel throughout the interior of the burner down to the vortex chamber is, however, not practicable in known burners of the aforesaid kind, since part of the flushing fuel would emerge from the final outlet orifice into the combustion chamber.

It is known to provide burners of a different type with discharge valves closing off the atomizing nozzle, thereby permitting'the circulation of heated fuel through the burner tube to flush out cold fuel before opening the valve. (See U. S. Patent No. 2,199,454.) However, no provision is made in such burners for circulation of fuel through a vortex chamber before opening-up the valve or for recirculation of fuel right up to the final outlet orifice so that the nozzles do not initially produce a well-defined spray, and dribble is often experienced.

An object of the invention is to provide, in a simple manner, for the recirculation of the liquid fuel within the burner right up to the final outlet orifice prior to starting up for the purpose of ensuring that any obstructions in the burner, such as solidified or semi-solidified fuel, are cleared before delivery of fuel into the combustion zone or chamber commences, with consequent ease of ignition and elimination of fouling.

A further object of the invention is: to enable a burner which is one of a plurality of separately controlled burners in a combustion chamber to be cooled by recirculation of liquid fuel right down to the vortex chamber when said burner is shut off and others in the combustion chamber remain in operation.

To this end, the present invention broadly comprises a liquid fuel burner of the kind hereinbefore set forth, in which there is provided a valve, carried by or associated with a displaceable member regulating the flow of the circulating stream through the swirling ports, vortex chamber and spill return line, e. g., by controlling the effective area of the fiow passageway for the circulating fuel stream (1. e., a displaceable member which acts either to vary the size or number of the swirling ports and/or the area of the spill return line), adapted to seat against and close the final outlet orifice of the burner when the displaceable member is moved to a position causing zero output of fuel flow through said final outlet orifice. It will be understood the effective fuel fiow through the outlet orifice is inherently dependent upon the regulation of the fiow of the said circulating stream of fuel. The invention is applicable both to burners wherein the said displaceable member is manually operated, and to those wherein it is actuated by fluid pressure.

Preferably, a spring-loaded valve is employed, the valve spring being under load when the valve is closed to such a degree that initial movement of the displaceable member from its closed position to increase the effective area of the swirling ports and/or to decrease the rate of spill, serves to remove such spring load whilst maintaining the valve in the outlet orifice closed. Conversely, when shutting down the burner the valve seats against and closes the outlet orifice before the control member is in its fully closed position, the remainder of its travel merely serving to increase the loading on the valve spring.

Movement of the displaceable member and, thus, control of the effective area of the fiow passageway for the circulating fuel stream (1. e., control of the effective area of the swirling ports and/or of the spill return line) may be effected automatically in response to the pressure of the liquid fuel; this can be effected by a common spring-loaded plunger effecting control both of the effective area of the swirl ports and of the spill return line, or by providing a separate spring-loaded plunger for each control, the plunger or each of the plungers responding to changes in liquid fuel pressure to control the efi'ective area of the swirling ports and the rate of spill over from the vortex chamber, respectively, as liquid fuel pressure changes. In certain instances one plunger only, controlling only one of these rates of fiow, may be used. Such arrangements are described, for example, in the aforesaid British patent specification.

Alternatively, movement of the displaceable member to regulate the effective area of the swirling ports or of the spill return line, or both may be effected manually, as by a piston or plunger having an operating rod extending externally of the burner and actuated by a lever or linkage mechanism which may, if desired, be under the control of a governor or the like associated with the plant or apparatus of which the burner forms a part. Equally, the regulating movement may Le effected by electrically, hydraulically, or pneumatically-operated means.

Two convenient embodiments of the burner according to the invention will now be described in detail by way of example, in which, in each instance, variation of the fuel flow is effected by a combination of control of the effective area of.

the swirling ports and control of the spill of fuel from the vortex chamber through the spill return line, both controls being actuated by a member manually or otherwise operable externally of the burner, the actuating means itself forming no part of the instant invention. Reference is made to the accompanying drawings forming a part of this specification, wherein:

Figs. 1a and 1b are longitudinal, vertical sectional views of the front and rear parts, respectively, of a burner according to the invention;

Fig. 2 is an enlarged, fragmentary vertical sectional view of the front of the burner;

Figs. 3. 4 and 5 are transverse section views taken on correspondingly numbered lines on Fig. 2; and

Fig. 6 is a fragmentary vertical sectional view showing a modified form of the burner tip.

Referring to Figs. 1 to 5 in detail, the burner is shown mounted within a guide tube i0 fixed to a furnace wall II. It comprises a main, outer housing or casing l2 having a rearward extension Ila threadedly secured to the rear, and a cap l3 similarly secured to its front. A final orifice plate [4 and the forward flange of a cylindrical, hollow swirl plug or sleeve l5, are clamped to the end of the casing by the cap l3, these parts being coaxial. The sleeve I5 is spaced from the casing to form an annular fuel supply space into which fuel may be fed under pressure from any source, not shown, through inlet fitting 16. The sleeve l5 has a series of tangential axially displaced swirling ports. In the illustrative embodiment shown, six parts are provided, arranged in pairs and located in three different transverse planes, the ports being designated by numbers Ila, llb and He, and the two forward ports Ila being smaller than the others. These ports communicate externally with the source of fuel. A hollow, displaceable piston or plunger I8 is mounted for axial displacement within the cylindrical bore of the swirl sleeve l5, and has a constriction at its forward end to provide an abutment for a purpose described hereafter, leaving a spill orifice through the constriction. The orifice plate M, the swirl sleeve 15 and the piston l8, between them, define a forced vortex chamber immediately to the rear of the final orifice.

The displaceable piston or plunger I8 is shaped so that it covers all swirling ports in the sleeve l5 when in its forward position shown in Figs. 145. It is provided with an external annular groove l9 located to communicate with fuel ports Ho and with the rear portions of fuel ports llb when the plunger is in its fully forward position. Radial ports 20 in the plunger place the groove I9 into communication with the interior of the plunger. While the ports 20 have been described as receiving fuel through fuel ports llb and He which are also swirling ports and function as such when uncovered by the forward edge of plunger 18, it is possible to employ other fuel ports in the swirl plug for this purpose, e. g., auxiliary ports farther back which never function as swirling ports. A spring-loaded needle valve 2| (also herein referred to as an orifice valve) is reciprocably mountedwithin the plunger l8 by means of a spider 22 or the like, its head seating against the inner edge of the final orifice in the plate I4, and its stem extending rearwardly through the constricted spill orifice at the front of the plunger. The forward edges of the vanes of spider 22 are shaped to engage the abutment formed by the constriction at the front of the plunger when the latter is retracted. The valve is urged forwardly by a spring 23, abutting the spider 22 and the .front face of a tubular connector 24. The dimensions of the spring 23 are such that the spring is under load when the plunger 18 is in its fully forward position so that initial retraction of the plunger serves to reduce the spring load, while the valve 2| is maintained in sealing contact with the final orifice. After release of all or part of the spring load, further retraction of the plunger withdraws the valve from the orifice by engagement of the forward edge of the spider vanes with the abutment at the front of the plunger.

Connector 24 is screwed into the rear of the plunger l8 and welded to the front end of tubular connecting rod 25 which extends rearwardly within casing I2 and is welded to a hollow plunger 26 rearwardly of the inlet port I6. The plunger 26 is slidable within a stationary bushing 21 secured to the casing section |2a by a cap 28. Reciprocation of the plunger 26 is effected through a connector 29 screwed into the bore of the plunger 26 and closing the rear end of the spill return duct therein, and having an internally threaded bore to which a suitable actuating rod 29a may be connected. A leak-tight seal is provided by a bellows 30 having its front ring 3| clamped between plunger 26 and connector 29, and its rear ring 32 clamped between the rear end of bushing 21 and a spacer ring 33 engaged by the cap 28.

Control of the spill of fuel from the vortex chamber through the spill orifice at the front of the plunger I8 and through the bores of the connector 24, rod 25 and plunger 26 is conveniently effected by a slide valve mechanism comprising radial ports 34 in the liner or bushing 21, an annular groove 35 on the outer face of the plunger 26 communicating with the internal bor of the plunger by radial ports 36. Ports 34 and groove 35 are positioned to be in complete communication when the plungers I8 and 26 are in their fully forward position. In this position the spill passageway is fully open. Axial movement of the plungers rearwardly maintains this fully open position for almost the first half of the total travel; continued movement places the groove progressively out of registry with the ports 34, so that communication is shut off completely just before completion of the travel. In this position the effective area of the spill has been reduced to zero. Fuel flowing outwardly from the plunger 26 through the ports 34 is discharged through a fitting 31.

A pin 38, fixed to the casing section |2a and sliding in a groove in plunger 26, prevents rotation of the latter. The rearward movement of the slidable parts is limited by a flange 39 on the connector 29. The forward movement is limited by abutment of an enlargement at the rear of the plunger I8 against the back of the swirl plug I5.

The burner operates as follows: Assuming the piston or plunger I8 to be in its fully forward position as shown, the needle valve 2| closed, and the supply of fuel to the burner cut off, fuel under pressure, e. g., heated oil, is first admitted through fitting I6. Fuel fiows forwardly through casing I2 about rod 25 and inwardly through the swirling port or ports in registry with the annular groove I9, viz.. the ports I") and He in the arrangement shown, and thence through the ports 26 into the interior of the plunger. The fuel thus entering spills back through the spill return line, i. e., through the connector 24, rod 25, plunger 26, ports 36, groove 35, ports 34 and fitting 31. The spill control comprising ports 34 and groove 35 are fully open in this position of the plungers and maximum spill is permitted. The oil also enters the vortex chamber forwardly of the plunger I8, but not with any tangential component of velocity (due to the radial disposition of the ports 20) and without issuing from the final orifice, the needle valve 2| being closed. In this Way flushing of the interior of the burner right up to the final orifice is achieved.

If heavy fuel oil, such as bunker oil, is being used such recirculation is continued at any desired pressure until all of the cold oil in the burner has been replaced by hot oil from the fuel reservoir. The fuel pressure is adjusted to the required starting level and the connector 29 is retracted, preferably in one continuous step, a distance of about half its total stroke. In the course of this first step the spill control is not appreciably altered by the movement of the plunger 26. The simultaneous movement of the plunger I8 effects the following: (1) The groove I9 is moved out of registry with the ports IIb and He, thereby momentarily interrupting the influx of fuel into the plunger I8. During this phase the valve 2| remains seated and the load on spring 23 is decreased; this loading may be decreased to zero, although it is not essential in every case that this be so, because the valve is subsequently positively lifted regardless of the spring. (2) Immediately following the cut-off of the groove I3, the valve 2| is lifted from its seat. (3) The plunger I3 begins to uncover the forward ports I 1a, and fuel enters the vortex chamber tangentially and forms a vortex. Since the valve 2| is lifted from its seat shortly before the opening of the ports |1a, free flow of atomized fuel into the combustion chamber is permitted and a good spray is obtained. Excess fuel continues to flow through the spill return line and fitting 31. The fully open position of the spill control and the minimum opening of the swirling ports result in a low effective flow of fuel through the outlet orifice.

Further retraction of the connector 29 beyond its half-way point may be gradual, and to any desired extent. Such continued retraction increases the effective fiow of fuel through the outlet orifice as follows: (1) The effective area of the spill control is gradually reduced by the progressive movement of groove 35 out of registry with ports 34. (2) The plunger I8 gradually increases the effective area of the swirling ports by progressively uncovering the larger ports HI) and, finally, the larger ports "0. When the plunger 26 has fully masked the ports 34 in the bushing 21 the spill outlet is fully closed and all oil fed through the ports I1a-I1c fiows out through the final spray orifice.

With combination of fuel pressure variation with regulation of the effective area of the tangential swirling ports and the rate of spill, a very wide range of fuel flow rates into the combustion chamber is obtainable. To shut down the burner the above procedure is reversed.

According to a. modified embodiment of the invention, illustrated inFig. 6, the bumer has a modified swirl plug and plunger, but in other respects is identical with that previously described. The swirl plug 40 is provided with one or more tangential swirling ports at each of at least two axially displaced transverse planes, indicated at Ma and HI). Port 4Ia, nearest the orifice plate I4, is of smaller diameter. The fuel passes under pressure from a fuel supply to the vortex chamber through the forward port 4|a, which is always uncovered by the plunger or piston 42, which is shorter than the plunger IB and has neither an annular groove nor radial holes.

The operation of this modified embodiment of the burner is similar to that previously described, except that when the plunger 42 is in .its fully forward position with the needle valve closed, fuel supplied under pressure enters directly into the vortex chamber through the swirling port or ports not covered by the piston. Since the final orifice is closed by the needle valve, the fuel so entering the vortex chamber returns or spills back to the fuel reservoir. In this position of the plunger, the spill plunger fully uncovers the ports in the liner 21 and allows maximum spill. In this way flushing of the interior of the burner right up to the final orifice is effected prior to the withdrawal of the plunger to open the needle valve. Again, initial retraction of the plunger serves to release the spring load on the needle valve 2| without opening the final orifice. As the plunger is withdrawn farther the tangential ports in the swirl plug are progressively uncovered and the needle valve is unseated. as in the previous embodiment.

The embodiment according to Fig. 6 has the advantage of simplicity, but the drawbacks that only a restricted path through the small ports la is provided for the preliminary circulation of oil (it being noted that the ports 2. in the previous embodiment are larger and in communication with several larger ports [1b and He); and that unless the initial retraction of the plunger is continued far enough, the valve 2| may not be well clear of its seat, resulting in imperfect spraying. However, by allowing sufficient time or providing sufficient pressure during the preliminary flushing out period, and exercising care in opening the needle valve, the burner gives good results.

I claim as my invention:

1. A liquid fuel burner of the type described having, in combination, a hollow swirl plug providing a vortex chamber therewithin; one or more swirling ports in the side wall of said plug for introducing fuel into the vortex chamber substantially tangentially thereof; an end wall for the vortex chamber; an outlet orifice in said end wall; a spill return passageway for said vortex chamber; a plunger reciprocably mounted with respect to said plug and arranged to vary 35 the effective area of said swirling ports upoit' reciprocating thereof, said plunger having a zero output position corresponding to zero flow of fuel through said outlet orifice, said plunger being shaped to admitfuel through at least some of said ports into the vortex chamber when in said zero output position to permit fuel to flow into the spill return passageway at or adjacent to the vortex chamber and to increase the effective area of said swirl ports during at least a part of its movement in a direction away from said zero output position; a valve adapted to seat against said outlet orifice; resilient means urging said valve against said outlet orifice axially movable with respect to said plunger; and means for retracting said valve from said outlet orifice when said plunger is moved in a direction fo; increasing the effective area of said swirling ports.

2. The liquid fuel burner according to claim 1 wherein the means for retracting said valve comprises an abutment movable with said plunger and operatively engageable with a part of the valve only after initial partial movement of the plunger in the said direction.

3. A liquid fuel burner of the type described having, in combination, a hollow swirl plug providing a vortex chamber therewithin; one or more swirling ports in the side wall of said plug for introducing fuel into the vortex chamber substantially tangentially thereof; an end wall for the vortex chamber; an outlet orifice in said end wall; a spill return passageway for said vortex; a throttling valve for said spill return passageway; a displaceable member comprising a plunger mounted reciprocably with respect to said swirl plug having a zero output position corresponding to zero fuel flow through said outlet orifice and arranged to decrease the effective area of said swirling ports upon movement thereof toward said zero position. said displaceable member being connected to actuate said throttling valve toward open position when the displaceable member and plunger are moved to decrease said effective area of the swirling ports, and vice versa, said plunger being shaped to admit fuel into the vortex chamber when in the zero output position to permit fuel to flow into the spill return passageway at or adjacent to the vortex chamber; an orifice valve adapted to seat against said outlet orifice; means urging said orifice valve against said outlet orifice; and means for retracting said orifice valve from said outlet orifice when said displaceable member is moved from said zero output position in a direction for increasing the effective area of said swirling ports.

4. The liquid fuel burner according to claim 3 wherein the said throttling valve has a fully open position and a flow restrictive position and is operatively connected to said displaceable member for actuation thereby to flow restrictive position only during continued movement of the displaceable member and plunger from said zero position beyond the position thereof at which the orifice valve is fully opened, whereby the throttling valve remains substantially in its fully open position when said orifice valve is seated and during the movement of said orifice valve from its seated position to its fully open position.

5. A liquid fuel burner of the type described having, in combination, a hollow swirl plug providing a vortex chamber therewithin; a plurality of axially displaced swirling ports in the side wall of said plug for introducing fuel into the vortex chamber substantially tangentially thereof; an end wall for the vortex chamber; an outlet orifice in said end wall; a spill return passageway for said vortex chamber; a plunger reciprocably mounted with respect to said plug,

and arranged to uncover at least some of said swirling ports for increasing the effective area of said swirl ports upon movement thereof in one direction, and to admit fuel into the vortex chamber when at its extreme position in the other direction to permit fuel to flow into the spill return passageway at or adjacent to the vortex chamber; a valve adapted to seat against said outlet orifice; means urging said valve against said outlet orifice; and means for retracting said valve from said outlet orifice when said plunger is moved from said extreme position in the said direction.

6. A liquid fuel burner of the type described having, in combination, a hollow swirl plug providing a vortex chamber therewithin; one or more swirling ports in the side wall of said plug for introducing fuel into the vortex chamber substantially tangentially thereof; an end wall for the vortex chamber; an outlet orifice in said end wall; a plunger reciprocably mounted within said plug and arranged to vary the effective area of swirl ports upon reciprocation thereof; a port in said plunger located for registry with a fuel port in said plug when the plunger is in a position for zero effective area of said swirl ports, and disposed to move out of registry with said fuel port when moved to increase said effective area; a spill return passageway for said vortex chamber; a valve adapted to seat against said outlet orifice; means urging said valve against said outlet orifice; and means for retracting said valve from said outlet orifice when said plunger is moved in a direction for increasing the effective area of said swirling ports.

7. A liquid fuel burner of the type described having, in combination, a hollow swirl plug providing a vortex chamber therewithln; a plurality of axially displaced swirling ports in the side wall of said plug for introducing fuel into the vortex chamber substantially tangentially thereof an end wall for the vortex chamber; an outlet orifice in said end wall; a tubular plunger reciprocably mounted within said plug and arranged to close said swirling ports when in its forward position and to uncover said ports progressively when retracted, the interior of said plunger being in communication with said vortex chamber; a port in said plunger located for registry with a fuel port in said plug when the plunger is in its forward position. and disposed to move out of registry with said fuel port when retracted; a valve movable axially with respect to said plunger and adapted to seat against said outlet orifice; resilient means urging said valve against said outlet orifice; and abutment means on said valve and on said plunger for retracting said valve when the plunger is retracted, said abutment means being spaced apart to come into operative engagement only after initial partial retraction of the plunger and before the uncovering of the forward swirling port.

8. A liquid fuel burner of the type described having, in combination, a hollow swirl plug providing a vortex chamber therewithin; a plurality of axially displaced swirling ports in the side wall of said plug for introducing fuel into the vortex chamber substantially tangentially thereof, the swirling port nearest the forward end of the vortex chamber having a smaller cross-sectional area than the swirling ports farther toward the rear; an end wall for the vortex chamber at the forward end thereof; an outlet orifice in said end wall; a tubular plunger reciprocably mounted within said plug and arranged to close said swirling ports when in its forward position, and to uncover said ports progressively when retracted, the interior of said plunger being in communication at its forward end with the vortex chamber; a port in said plunger located for registry with a fuel port in said plug when the plunger is in its forward position, and disposed to move out of registry with said fuel ports chamber uncovered when the plunger is in its fully forward position, the interior of said plunger being in communication at'its forward end with the vortex chamber; a spill return passageway in communication with the rear end of said hollow plunger; a valve within said vortex chamber adapted to seat against said outlet orifice; means urging said valve against said outlet orifice; and abutment means on said valve and on said plunger for retracting said valve when the plunger is retracted.

10. In combination with a liquid fuel burner having a vortex chamber, an outlet orifice in one wall of said chamber, a fuel supply passagewhen retracted a distance suflicient to open the said swirling port nearest the forward end of the vortex chamber; a valve within said vortex chamber movable axially with respect to said plunger and adapted to seat against said outlet orifice; resilient means urging said valve against said outlet orifice; abutment means on said valve and on said plunger for retracting said valve when the plunger is retracted, said abutment means being spaced apart to come into operative engagement only after initial partial retraction of the plunger and before the uncovering of the said swirling port nearest the forward end; and a spill return passageway in communication with the rear end of said hollow plunger.

9. A liquid fuel burner of the type described having, in combination, a hollow swirl plug providing a vortex chamber therewithin; a plurality of axially displaced swirling ports in the side wall of said plug for introducing fuel into the vortex chamber substantially tangentially thereof; an end wall for the vortex chamber at the forward end thereof; an outlet orifice in said end wall; a tubular plunger reciprocably mounted within said plug and arranged to close some of said swirling ports and leave at least the swirling ports nearest the forward end of the vortex way, fuel inlet openings in one or more walls of said chamber for introducing fuel from said supply passageway into the chamber comprising one or more swirling ports disposed in a direction to form a vortex in the chamber, and a spill return passageway in communication with the said chamber for the discharge of fuel therefrom, arranged to permit the flow of a circulating stream of fuel successively through said fuel supply passageway, fuel inlet openings, vortex chamber and spill return passageway: a displaceable member having a zero output position corresponding to zero flow of fuel through said outlet orifice and a position displaced therefrom; flow control means for said fuel inlet openings to regulate directly the flow of said circulating stream and, hence, the flow of fuel through said outlet orifice connected for actuation by said displaceable member; a valve adapted to seat against said outlet orifice; means responsive to movement of said displaceable member toward said zero output position for seating said valve against said orifice; and means responsive to movement of said displaceable member away from said position for opening said valve.

11. In combination with the burner according to claim 10, a throttling valve in said spill return passageway arranged for actuation by said displaceable member and disposed to open said throttling valve when the displaceable member is moved toward said zero output position and to close said throttling valve when the displaceable member is moved away from said position.

12. In combination with a liquid fuel burner having a vortex chamber, an outlet orifice in one wall of said chamber, a fuel supply passageway, fuel inlet openings in one or more walls of said chamber for introducing fuel from said supply passageway into the chamber comprising one or more swirling ports disposed in a direction to form a vortex within the chamber, and a spill return passageway in communication with the said chamber for the discharge of fuel therefrom, arranged to permit the flow of a circulating stream of fuel successively through said fuel supply passageway, fuel inlet openings, vortex chamber and spill return passageway: a displaceable member provided with means for controlling the flow of said circulating stream and having a zero output position corresponding to zero flow of fuel through said outlet orifice and a position displaced therefrom; a, valve within said vortex chamber adapted to seat against said outlet orifice and movably mounted with respect to said displaceable member; resilient means for seating said valve against said outlet orifice; and means cooperating with said displaceable member and operative only after partial movement of said displaceable member in a direction away from said zero output position for opening said 11 valve in response to continued movement of said displaceable member away from said position.

13. The combination according to claim 12 wherein the means for controlling the flow of the circulating stream comprises a plunger having a wall movable over said inlet openings for closing the openings, said plunger being positioned on said displaceable member so as to leave at least some of said openings open to admit fuel into the vortex chamber when the displaceable member is in said zero output position and to cover and close at least some of said openings to restrict the admission of fuel into the vortex chamber during the initial movement of the displaceable member away from said position in the said direction, the extent of said wall being such that said swirl ports are uncovered and their effective area is progressively increased during continued movement of the displaceable member in the said direction.

14. The combination according to claim 13 wherein said means for opening the valve comprises abutment means movable with the valve and with the displaceable member, respectively, said abutment means being positioned to be spaced apart when the displaceable member is in zero position and to come into engagement to open said valve before said wall of the plunger uncovers said swirl ports, whereby the valve is opened before commencement of delivery of fuel through said swirl ports into the vortex chamber.

15. The combination according to claim 12 wherein the means for controlling the flow of the circulating stream comprises a plunger having a wall movable over said inlet openings for closing some of the openings, said plunger being positioned on the displaceable member to leave some of said swirl ports uncovered in all positions of the displaceable member, and being movable therewith to uncover said swirl ports and increase their effective area during movement of the displaceable member in the said direction.

JOHN RUSKIN JOYCE.

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

UNITED STATES PATENTS Number Name Date 1,051,908 Normand Feb. 4, 1913 1,326,488 Fisher Dec. 30, 1919 1,333,612 Fisher Mar. 16, 1920 1,644,372 Gray Oct. 4, 1927 2,308,909 Blanchard Jan. 19, 1943 2,345,402 Lubbock et al Mar. 28, 1944 2,411,181 Altorfer Nov. 19, 19 6

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