US2969925A

US2969925A - Multiple variable area orifice injector

Info

Publication number: US2969925A
Application number: US712978A
Authority: US
Inventors: Paul D Burgess; Henry F Rothwell
Original assignee: Delavan Manufacturing Co
Current assignee: Delavan Manufacturing Co
Priority date: 1958-02-03
Filing date: 1958-02-03
Publication date: 1961-01-31
Anticipated expiration: 1978-01-31

Description

Jan. 31, 1961 P. D. BURGESS ETAL MULTIPLE VARIABLE AREA ORIFICE INJECTOR Filed Feb. 3, 1958 2 Sheets-Sheet 1 ATTORNEYS.

Jan. 31, 1961 P. D. BURGESS ET AL 2,969,925

MULTIPLE VARIABLE AREA ORIFICE INJECTOR I 2 Sheets-Sheet 2 Filed Feb. 3. 1958 /N VE N TORS MULTIPLE VARIABLE AREA ORIFICE INJECTGR Paul D. Burgess and Henry F. Rothwell, West Des Moines, Iowa, assiguors to Delavan Manufacturing Company, West Des Moines, Iowa, a corporation of Iowa Filed Feb. 3, 1958, Ser. No. 712,978

8 Claims. (Cl. 239-453) This invention relates to a fluid distributing device, or fuel injector, useful in jet engines of the kind commonly used in aircraft.

A primary object of the invention is to provide a fluid distributing device having a plurality of discharge lines, each of which is capable of discharging continuously a uniform predetermined quantity of liquid.

Another object is to provide a fluid injector device which is supplied with pressurized fluid from a single line and which may be adjusted to provide a wide fiow range at each discharge port within a relatively narrow pressure control range.

Another object is to provide a variable area type multiple orifice fuel injector for use with a burner such that a mechanical fuel metering means is outside the high temperature confines of the burner but near enough to the point of injection to minimize variation due to difference in head imposed at discharge openings located some distance apart.

In one form of the invention the injector device comprises a body or housing having a central manifold bore connected to the fluid supply line and a plurality of discharge bores leading from the manifold orifice. Each of the discharge bores in turn connects with a discharge conduit. The conduits are of different lengths to provide distribution of liquid ejected therefrom at points spaced outwardly from the manifold bore. Each of the discharge bores contains a valve which is spring biased to closed position. Fuel flows through the valve when a predetermined pressure is exerted on the poppet member within the valve. Preferably, the biasing spring force for each valve is individually adjustable to permit regulating the volume of fuel passing through the valve to the discharge conduit.

Another object of the invention is to provide a variable area type multiple orifice injector having passages at the injection points which are larger than would be required to deliver the desired maximum flow at maximum available pressure, thus minimizing clogging.

A further additional object is to provide a compact group of parallel variable area metering devices which are free from any self-induced vibration which might affect the accuracy of the fuel metering.

These and other objects will become apparent from the following description when read in conjunction with the accompanying drawings, wherein:

Figure 1 is a side elevational view of an injector device constructed in accordance with the invention;

Figure 2 is an end elevational view of the device shown in Figure 1;

Figure 3 is a plan view of the device shown in Figure 1, setting forth in broken lines the arrangement of the internal bores;

Figure 4 is an enlarged sectional view taken along the line 4-4 of Figure l; and

Figure 5 is a schematic sectional view through a turbojet afterburner showing the fuel injector of the invention in operative position.

atent 2,959,925 Patented Jan. 31, 1961.

Referring now to the drawings, the body 10 may be made from a block of stainless steel or other suitable high temperature corrosion resistant metal which is machineable. If desired, the body may be cast or forged, in which case the external configuration may be suitably contoured to reflect the internal configuration, thus effecting an over-all weight reduction. A relatively large diameter blind manifold bore 12 extends into the body from one side. At the bore opening an inlet fitting 13 is provided having external threads 15 for connecting the fluid supply line to the device. Fitting 13, and others connected to the body, are permanently secured thereto by means of a suitable high temperature resistant brazing alloy such as nicro-brazing alloy. In most instances the injector device is used for fuels but it will be understood that it is capable of operation with any type of fluid Where it is desired to discharge the same at a controlled concentration within a relatively large space. A plurality of discharge bores 14 are drilled into the body 10 and communicate with the manifold bore 12. In the preferred form of the invention, as best shown in Figure 3, the discharge bores cross the manifold bore 12 and are disposed at right angles thereto. The bores 14 thus are divided by the manifold bore into two sectionsthe blind openings 16 extending beyond manifold bore 12 and discharge passages 18 interconnecting the bore 12 with discharge ports leading from the body.-

Although three discharge bores 14 are illustrated in the drawing, it will be understood that any number from two to five or more may be employed depending upon the intended use for the device. The discharge passages 18 are slightly enlarged at the outlet or downstream end and are internally threaded, as indicated at 20 in Figure 4. The enlarged diameter portion provides a shoulder 22 which is adapted to cooperate with an internal sleeve or valve seat member 24 having a radial fiange 26. The flange 26 is sealed against the shoulder 22 by means of a resilient fuel resistant gasket 32 interposed therebetween. Sleeve 24 is locked within the body by means of plug 34, and has a central opening 51 therethrough which terminates at the downstream end in a circumferential seat 28 adapted to cooperate with a poppet valve for regulating fluid flow, as explained hereinbelow. The upstream end of the sleeve or valve seat member has a bevelled internal edge 30. For purposes of assembling the device, the sleeve 24 (and the valve seat provided thereby) is separate from the body 10, but it will be understood that the construction could be modified so that the valve seat 28 is formed integrally with the body.

The open end of the discharge passage 18 is sealed by means of hollow plug 34 which is externally threaded and adapted to screw into the threads 20. The plug 34 has an annular circumferential groove 36 which communicates with the hollow interior of the plug through a plurality of circumferentially spaced openings 38. The top of the plug 34 is slightly larger in diameter than the opening and is cut out to seat against the end of the body. A gasket 40 is provided to effect a fluid-tight seal. To facilitate tightening the plug within the discharge passage 18 a plurality of wrench holes 35 are drilled into the face of the plug cap. The end of plug 34 bears against fiange 26 of the sleeve 24, as indicated. The body 10 has a radial opening or discharge port 41 communicating with each of the discharge passages 18 near the outer end thereof. A suitable integral flange 42 is provided for connecting the discharge conduit 44 to the port 41. Thus fluid passing through the discharge passage 18 will flow radially through the openings 38 with a similar connection to its own discharge conduit. As shown in Figure 1, the first discharge passage has a conduit 80, the central discharge passage has a conduit 44 and the third discharge passage has a conduit '73, all being of different lengths, to distribute the fluid over a wide lateral area. The conduits are brazed to the ports 41 in the body- To regulate the flow of fluid through the central opening 51 in the sleeve 24-, a poppet, indicated generally at 46, is provided. The poppet is preferably made from stainless steel and comprises a stem 48 which terminates at one end in a bulbous head i? which is larger in diameter than the seat 23 with which it cooperates to close off the flow of fluid. The head 5t} contains a screwdriver slot 52 to permit regulating the biasing force, as explained below. aThe end of the poppet opposite the head termimates in threads 54 on which a nut 53 is screwed. The nut has a hemispherical bearing surface 62 and is adapted to slide within the blind opening 16 like a piston within a cylinder. Thus the nut serves as a dashpot for dampening movement of the poppet. The nut may be locked against rotation on the stem 48 by crimping tubular portion 61 into milled opening 56 of the poppet. Coil spring 64 encircles the stem 45% of the poppet and is compressed between the sleeve 24- and the nut 53. It will be noted that the eflect of the spring is to bias the poppet to closed position against the valve seat 2%.

In order to insure axial force against the poppet even though the ends of the spring 64 may not be perfectly square, we have provided a pair of spring guides in the form of

bosses

66 and 70 against which the ends of the spring may bear. Boss 66 has a bevelled surface 68 complementing the spherical surface 62 of the nut 58 which it contacts. Thus the spring may distort the position of the boss 66 with reference to the center line through the bore 14 but the force exerted against the nut is always in an axial direction and obviates increased frictional drag. Boss 66 has a relatively large central opening 67 through which the stem 48 extends. Boss 70, at the opposite end of the spring, has a contacting surface 72 which is a segment of a sphere and bears against the bevelled surface 30 on the inside diameter of the sleeve 24 for the purpose explained above with respect to boss 66. Central opening 73 through boss 70 is sufflciently large to permit movement of the boss with respect to the stem 48 and to permit flow of fluid therethrough from the manifold bore 12 into the discharge passage 18.

A mounting bracket 74 is welded or otherwise suitably connected to the body 19 for mounting the device. A plurality of holes 76 are provided in the flange of the bracket 74 for this purpose. The upper ends of the bracket may be brazed to the body is or otherwise connected thereto.

An injector of the type described is shown in Figure 5 in operative position within the afterburner of a jet engine. The burner casing 32. terminates at its discharge end in an exhaust nozzle 99. The gas generator portion 84 is at the opposite end and gases therefrom flow at high velocity around the tail cone $6 in the direction of the arrows. It is desired to burn fuel in the afterburner or combustion chamber to produce expanded gases for additional thrust. It is important that the fuel be discharged uniformly over the cross-sectional area of the afterburner around the tail cone. Flame holders 88 are provided downstream of the tail cone. The injector of the invention is mounted on the shell or casing 82 of the afterburner with the

discharge conduits

86, 44 and 78 extending radially through an opening into the space surrounding the tail cone. A plurality of such units may be provided at spaced points around the afterburner although only one is shown in the drawing. The regulating portion of the injector device is disposed outside .the burner and, consequently, is not subjected to the intense temperatures prevailing therein. The pressurized fuel supply .(not shown) connec to the in et fi t n 13 The fuel flows from the fitting 13- into the manifold bore 12. The compression of springs 64 is adjusted individually for each of the discharge bores 14 so that more or less fuel may pass through the different valves at the pressure prevailing in the manifold bore 12. Pressure within the manifold 12 lifts the poppet 46 from the seat 28 to permit flow of fluid from the manifold 12 into the discharge passage 18. From the passage 18 the fuel flows through the openings 38 into the annular space 3.6 and out the port 41 into the

discharge tube

44, 86 or 78 as the case may be.

It will be appreciated that a wide variation in the volume of fluid emitted from each of the discharge conduits can be obtained although the pressure from the single fluid source connected to the inlet fitting l3 varies over a relatively narrow range. The volume discharged from each conduit may be equal or different, as required, for most eflicient combustion. Volume adjustment is accomplished by turning the popet vt6 in the nut 58 to vary the compression of the spring 64. The locking means 6% is bent into operative position after the desired compression has been obtained. Slight rapid variations in pressure and vibration conditions which normally affect the position of the poppet with respect to the valve seat 23 are minimized by the unique construction of the nut 58 which acts as a dashpot within the blind opening 16. Improved accuracy is also obtained by reason of the spring guide arrangement since other than normal spring ends do not result in a non-axial force which causes increased frictional drag resultingin hysteresis and consequent inaccurate calibration.

It has been found that devices constructed in accordance with this invention are capable of reproducing the original accuracy of operation after having been subjected to elevated temperatures in the range of 1000" F.

In the prior art injector tubes which consist essentially of a hollow tube having a plurality of orifices therein, the orifices had to be relatively small to meter out the correct amount of fuel under the fuel supply pressure. Consequently, there was much difliculty in clogging of the openings. By using the device of the invention containing valves, the discharge tubes may be of relatively large diameter while yet restricting the flow. The clogging problem is substantially eliminated.

it will be understood that various modifications may be made in the injector device of the invention without departing from the true spirit and scope of our invention. For example, the axes of the discharge tubes may be parallel rather than normal to the axes of the poppets. Other modifications will occur to those skilled in the art. it is not our intention to limit the invention other than as necessitated by the scope of the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A fluid distributing device comprising a body, a manifold bore disposed within the body having a fluid inlet fitting connected thereto, a plurality of fluid outlet bores for discharging fluid in a predetermined pattern, each bore extending through the wall of said body and crossing with said manifold bore, thus forming a blind opening beyond the manifold bore and a discharge passage leading from said manifold bore to a-point outside said body, said discharge passage having a valve seat therein, a poppet within said outlet bore comprising a stem terminating in a head at one end, said head being disposed on the downstream side of said seat for regulating fluid flow past said seat, said stem having a pistonlike nut on the end opposite said head slidably disposed within said blind opening to serve as a dashpot to dampen movement of said poppet and a coil spring encircling said stem and having one end bearing against theupstream side of said valve seat and the opposite end hearing against said nut, thus biasing said head toward said seat and permitting said head to lift when fluid pressure within said manifold bore exceeds the biasing force of said spring.

2. The device of claim 1 wherein bearing bosses for receiving the opposite ends of said spring engage said upstream side of the valve seat and said nut, the bosses and the surfaces against which they bear comprising a ball and socket type contact to insure uniform circumferential pressure on said nut when the ends of said springs are not perfectly plane.

3. The device of claim 1 wherein said nut is adjustable with respect to said stem to adjust the compression of said spring and hence the fluid pressure required to lift said poppet.

4. A fluid distributing device comprising a body, a manifold bore disposed within the body having a fluid inlet fitting connected thereto, a plurality of fluid outlet bores, each extending through the wall of said body and crossing with said manifold bore, thus forming a blind opening beyond the manifold bore and a discharge passage leading from said manifold bore to a discharge port connecting to said passage, a conduit connecting to each said discharge port, a hollow plug sealing the end of said passage and having a plurality of circumferentially disposed openings therethrough communicating with said port, said discharge passage having a valve seat therein, a poppet within said outlet bore comprising a stem terminating in a head at one end, said head being disposed on the downstream side of said seat for regulating fluid flow past said seat, said stem having a pistonlike nut on the end opposite said head slidably disposed within said blind opening to serve as a dashpot to dampen movement of said head, and a coil spring encircling said stem and having one end bearing against the upstream side of said valve seat and the opposite end bearing against said nut, thus biasing said head toward said seat and permitting said head to lift when fluid pressure within said manifold bore exceeds the biasing force of said spring.

5. The device of claim 4 wherein said valve seat coinprises part of a flanged sleeve locked within said discharge passage by means of said hollow plug.

6. A fluid distributing device for discharging fuel into a combustion chamber in a predetermined pattern comprising a body mounted outside the combustion chamber, a manifold bore disposed Within the body having a fluid inlet fitting connected thereto, a plurality of fluid outlet bores extending through the wall of said body normal to said manifold bore and communicating therewith, a discharge conduit communicating With each of said outlet bores and extending into said combustion chamber, said discharge conduits each being of a different length to control distribution of fluid within said combustion chamber, each of said outlet bores containing a valve seat and a poppet mounted within said bore for movement toward and away from said seat to regulate fluid flow through said bore, resilient means for biasing said poppet toward said seat in opposition to fluid pressure within the manifold bore, and means for adjusting each said resilient means to increase or decrease the biasing force imposed on said poppet.

7. The device of claim 6 wherein said discharge conduits extend outwardly from said body normal to said outlet bores and parallel to each other.

8. The device of claim 1 wherein said poppet head is tapered toward said stem to provide rapid increase in flow as said head is lifted from said seat.

References Cited in the file of this patent UNITED STATES PATENTS 308,479 Falk Nov. 25, 1884 1,645,722 Raymond Oct. 18, 1927 1,935,874 Davis Nov. 21, 1933 2,345,140 McCollum Mar. 28, 1944 2,645,243 Turner July 14, 1953 2,806,354 Cook Sept. 17, 1954