US2971521A - Fuel control initiator - Google Patents

Description

Feb. 14, 1961 D. A. WASHBURN FUEL CONTROL INITIATOR 4 Sheets-Sheet 1 Filed 001;. 11, 1950 INVENTOR.

DAVID A. WASHBURN BY 4 (973m flTTy.

Feb. 14, 1961 D. A. WASHBURN ,971, 21

FUEL CONTROL INITIATOR Filed 001;. 11; 1950 4 Sheets-Sheet 2 FIG. 2

INVENTOR. DAVID A. WASHBURN Feb. 14, 1961 D. A. WASHBURN ,971,521

FUEL CONTROL INITIATOR Filed Oct. 11, 1950 4 Sheets-Sheet 3 INVENTOR.

DAVID A. WASHBURN D. A. WASHBURN FUEL CONTROL INITIATOR Feb. 14, 1961 4 Sheets-Sheet 4 Filed Oct. 11, 1950 INVENTOR.

DAVID A WASHBURN BY %z (WM FIG. 8

FIG. 9

United States Patent Ofifice 2,971,521 Patented Feb. 14, 1961 FUEL CONTROL INITIATOR David A. Washburn, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed Oct. 11, 1950, Ser. No. 189,599

Claims. (Cl. 137-72) The present invention relates to fuel feeding. More specifically it relates to a device for controlling the flow of liquid fuel to the burner area of an aerial vehicle, such as a ram jet projectile, which must be assisted into flight by booster rockets, and wherein fuel is not fed in normal quantities to the burners until after the vehicle has reached sufiicient acceleration to sustain free flight and the booster rockets have separated therefrom.

In the flight of a ram jet projectile the air/fuel ratio in the burner area is of vital importance. A fuel-control valve, therefore, is necessary to regulate the flow of fuel into the burner area to compensate for the various changes in air pressures encountered during the flight of said projectile in order to provide a constant ratio of air to fuel in said burner.

Heretofore it has been customary to pre-set the fuel control valve to provide a slight fuel flow to the burner area coincident with the launching of the projectile; however, due to the unsteadiness of flight during the first few seconds thereof this valve setting is often altered. Tests disclosed that this alteration of the valve setting during the early flight stage sometimes flooded the combustion cchamber, if the valve shifted to its open position, or starved the said chamber if it fully closed, with a resultant miss-fire or a condition of extremely erratic burning during the early part of the flight of the projectile.

An object of the present invention, therefore, is to provide means that initially will lock the fuel flow control device at a certain constant setting and will allow variable fuel feed to the ram-jet burner to start only after the vehicle reaches operative speed.

More specifically, an object of the invention is to provide a fuel valve lock that will become disengaged automatically after the lapse of a predetermined period.

Other objects and many of the attendant advantages of this invention will be appreciated readily as the same becomes understood by reference to the following detailed description, when considered in connection with the accompanying drawings, wherein:

Fig. 1 is a partially diagrammatic illustration showing a fuel control valve in section, and indicating its connections to a ram jet projectile, the flow initiating means constituting the present invention being shown largely in side elevation but partly in section, to indicate how the invention is applied;

Fig. 2 is a fragmentary side elevation illustrating the invention mounted on a missile;

Fig. 3 is a plan of the structure shown in Fig. 2;

Fig. 4 is a sectional view on the plane 4--4 of Fig. 2;

Fig. 5 is a fragmentary transverse sectional view, on the same plane as Fig. 4, but showing the locking device disengaged from its coacting valve stem;

Fig. 6 is a fragmentary section taken on plane 66 of Fig. 4;

Fig. 7 is an exploded view of the locking mechanism forming part of the invention;

Fig. 8 is an enlarged detail section of a squib block,

taken on plane 8-8 of Fig. 2; and

Fig. 9 is an enlarged detail sectional view of the squib block, on the line 9-9 of Fig. 8.

Referring first to Fig. 1, the fuel control valve 1 has a fuel inlet 2 and a fuel outlet 3, connected respectively to a fuel source, not shown but which supplies fuel to said valve under relatively high pressure, and to the fuel transfer line 4 which leads to the injector 5 of the ram-, jet 6, said ram-jet and injector being indicated merely diagrammatically, as they form no part of the present invention.

The control valve 1 has a connection to a source 7 of ram pressure and a source 8 of atmospheric pressure, both indicated diagrammatically, said atmospheric pressure controlling a valve plunger 9 through the Sylphon 10 to regulate the supply of ram pressure. A pressure differential is therefore provided on opposite faces of a piston 11, modified however by controlled leakage through a hole 12. of definite size in said piston 11. The valve plunger 9 controls the free passage of ram pressure air through an annular seat 26, by reason of a contoured end 2 7 of said valve plunger, as shown. Through a rod 13, the piston 11 pushes against a rod 14 having a Separator disk 15 attached thereto, said disk acting as a piston, to one face of which (the lower face as shown in Fig. 1) is applied to the pressure of the fuel in the outlet 3, communicated through the passage 16, While the opposite face, the upper face, is subjected to the pressure in the chamber 18 communicated to said face through the orifices 18a in the partition 1812. A manually operated fuel control valve 17, the purpose of which will be described hereinafter, is disposed in a chamber 17a located on the fuel outlet side of the chamber 18.

The rod 14 has a reduced portion 19 on which slides a valve 20 with an alinement spring 2 1 interposed between said valve and a shoulder 22 on said rod 14. A circumferential groove 23 is provided near the upper end of the reduced portion 19 of the rod 14. The valve moves in a cylindrical sleeve 24, and has ports 25 therein, controlling the communication between the inlet 2 and the chamber 18. The valve 2t) is maintained in desired position on rod 14 by the snap washer 32, shown on the reduced portion 19 in Figs. 1 and 4, the spring 21 serving to push the valve against said washer.

As described above, the piston 11 is shifted as the atmospheric and ram pressure differential increases or decreases. The automatic mixture-control unit, which includes the Sylphon 10, the plunger 9 and the annular seat 26, compensates for altitude enrichment. More specifically, the metering plunger 9 is positioned relative to the seat 26, which the ram pressure must pass to reach the piston 11, by the Sylphon 10 and a spring 10a cooperating therewith. As the external pressure on the bellows changes with altitude, the Sylphon expands or contracts for moving the metering plunger out of or into the annular seat. The plunger end 27 can be contoured to produce any desired altitude regulation. The pressure difierential across the piston 11 is approximately proportional to the square of the change in velocity of the missile, and consequently to the square of the change in mass air flow, assuming no spill-over conditions. This pressure difference is balanced by a pressure diflference acting on the fuel disk 15, resulting from the flow of fuel through an adjustable orifice provided by the fuel control valve 17. A pressure drop in the outlet side of the valve 17 is provided by said valve and is proportional to the rate of flow therethrough. This pressure drop cooperates through the passage 16 to the lower face of the disk 15 to provide a fuel pressure differential on said disk surfaces. When the fuel flow exceeds or drops below that required to maintain a balance, or constant air/fuel ratio,

the pressure drop across the valve 17 exceeds or drops below a predetermined value, causing an unbalance between the forces of the air and fuel pistons. This unbalance causes a slight movement of the valve 20, and readjusts the fuel flow to the fixed air/fuel ratio.

To achieve flexibility of air/fuel control the control valve 17 can be positioned by a calibrated external knob. By turning the knob the orifice area through which the fuel flows can be varied to determine what mixture provides the best combustion or greatest thrust in flight. This regulator is calibrated over a range of air/ fuel ratio between 12.5 :1 and 25:1. The effective operating altitude of the valve 1 is approximately 40,000 feet and within a Mach range of 1.2 to 2.0.

A detent or catch 28 has been provided to temporarily lock the valve 20, during the first few seconds of the flight of the projectile, in order to impede the fuel flow to the combustion area of said projectile prior to the ignition thereof. As best shown in Figs. 4, and 6, the catch 28 has a bored hub 29, secured to the shaft 30 to be turned thereby, and a latch 31 extending radially from said hub at one end, said latch 31 being of proper length and thickness to engage in the groove 23 when properly positioned, as indicated in Figs. 1, 4 and 6, and to become disengaged therefrom when turned to the position shown in Fig. 5 (in dot-dash lines in Fig. 6).

The detent 28 is shifted by a spring 33 acting on an arm 34 of an operating lever 35 secured to the outer end of the shaft 30. This spring is in tension as illustrated and urges the shaft 30 in the counter clockwise direction, as seen in Fig. 6, thus tending to shift the latch into unlatched position, as shown in broken lines in Fig. 6. In this position, the latch is disengaged from the groove 23 and the rod 14 may rise, due to pressure acting on the disk 15, piston 11, etc. as already described.

As a result the valve may rise and full communication thus be established through the ports thereof, between the fuel inlet 2 and the fuel outlet 3, as will be clear from a scrutiny of Fig. 1.

In order to control the time at which the valve 20 opens, a soft copper wire 37 is secured to the arm 36 of lever for holding said arm in proper position to keep the latch engaged in the groove 23, and means are provided to sever said wire 37 at the desired moment. Said means, shown in detail in Fig. 9, comprises a delayedaction squib 41 contained in a housing 42. This housing is threaded into a fitting 38, which has a passage 39 through which the hot combustion products of the squib will discharge when said squib detonates, which is preferably accomplished by electrical ignition through the conductors 40. The wire 37 passes through the opening 39 and thus will be subjected to the heat and the disruptive action of the detonation, with the result that said wire will be severed by melting and/ or breakage.

As it is desirable to hold the squib 41 firmly in place, and yet to leave the passage 39 unobstructed, a screw 43 having a reduced end 44 is threaded into the fitting 38 and said end then provides an abutment for the inner end of said squib, as shown in Fig. 9. This end 44 need extend only a short distance into the passage 39, leaving the bore substantially free.

The wire 37 extends through the transverse part of the passage 39, and then through a small hole 45, the free end 46 of the wire then being bent sharply to hold it in place. It will be noted that the portion of said wire that is within the passage 39 is being held out of contact with the wall of said passage, so that it is exposed on all sides to the heat and combustion products, as well as the debris, produced when the squib detonates.

The operation of the invention will be clear from the description of the structural features thereof, but for convenience may be summarized briefly as follows:

When the missile is being launched, the wire 37 initially will hold the lever 35 in such position that the detent 28 will maintain the valve 20 in closed position, thus pre- 4 venting flow of fuel to the injector 5 at this time, except for the small fixed flow that takes place through the-portions of the ports 25 above the partition 47.

The amount of the fixed flow may be controlled by means of a bushing 47, threaded into an opening 49, Figs. 4 and 5, which constitutes the bearing for shaft 30. The detent 28 abuts the bottom of said bushing, whereby the vertical position of the detent may be adjusted by screwing the bushing into or out of the opening 49. Nut 51 on shaft 30 may be adjusted to take up any vertical play, and nut 50 will then serve as a lock nut to hold such adjustment, while nut 48 serves to lock the bushing 47 in adjusted position. Inasmuch as the latch 31 of the detent will hold the valve rod 14 at a corresponding vertical position, this adjustment provides a delicate setting of the position of the valve 20 so that the ports 25 are open to just the extent desired for the fixed orifice action of said ports during the launching period.

This small flow of fuel is sutficient to start and maintain combustion, but has no material propulsive effect, and is intended only to tide over the initial period, during which rockets are accelerating the missile to a speed at which the ram jet action can start. This initial period is approximately 4 to 6 seconds, but may vary for different types of missiles.

The detonation of the squib at the proper corresponding time is predetermined by the specific time delay of the squib that is used. The ignition of the squib takes place simultaneously with the ignition of the launching rockets, but detonation of said squib is deferred by the characteristic delay features built into said squib itself. Upon such detonation of the squib, a rush of hot gases and particles of metal and other debris will discharge through the passage 39, heating and softening, or even melting, the wire 37, and also mechanically disrupting it and blowing it out of the said passage. Thereupon the spring 33 will pull the arm 34 around, turning the shaft 30 to release the rod 14 from the detent, and allowing it to move upward, thus opening the ports 25 of valve 20 and establishing a flow path for the fuel from inlet 2 to outlet 3 through said ports. From then on the flow of fuel is controlled automatically by the valve 1 previously briefly described, the detailed operation of which, however, is not a part of the present invention.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. H is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A fuel flow control mechanism comprising a casing having a fuel inlet opening and a fuel outlet opening, a valve in said casing to control the flow of fuel between said openings, a valve rod movable axially in said casing and carrying said valve, a shaft extending into said casing, a latch carried by said shaft, and coacting with said rod to hold it against axial movement when in one position and to free said rod when in another position, and means outside said casing and operable to release the rod for axial movement, said means including a spring urging the latch out of engagement with the rod, 8. wire restraining the spring and maintained under tension by said spring, and a device for severing said wire and thus releasing the spring to move the latch.

2. A fuel flow control mechanism as recited in claim 1, wherein said device includes a squib.

3. A fuel control mechanism comprising a casing having a fuel inlet opening and a. fuel outlet opening, a valve in said casing controlling the flow of fuel between said openings, an axially movable valve rod carrying said valve, a shaft extending into said casing, a latch carried by said shaft and coacting with said valve rod to hold the rod against axial movement when the latch is in one position and to free said rod when in another position, means outside the casing tending to turn said shaft and thereby release the rod for axial movement, said means lIlCllldlIlg a lever secured to the shaft, a spring connected between said lever and the casing, a destructible wire for holding the latch in the first mentioned position, and a delay squib for breaking said destructible wire to free the lever.

4. A fuel flow control mechanism comprising a casing having a fuel inlet opening and a fuel outlet opening,

a valve in said casing to control the flow of fuel between said openings, a valve rod movable axially in said casing and carrying said valve, a shaft extending into said casing, a latch carried by said shaft, and coacting with said rod to hold it against axial movement when in one position and to free said rod when in another position, means outside said casing to turn said shaft and thereby release the rod for axial movement, said means including a lever carried by said shaft outside the casing, a spring attached to one end of said lever and urging the shaft to move the latch into releasing position, destructible retaining means holding the other end of said lever against the urging of said spring, and a squib for destroying said destructible means, whereby the spring may turn said lever.

5. A fuel flow control mechanism as recited in claim 1, including means outside of the casing for adjusting the valve rod axially, whereby said valve may be adjusted for permitting a fixed fuel flow.

References Cited in the file of this patent UNITED STATES PATENTS 824,934 Jenczewsky July 3, 1906 971,089 Stankiewicz Sept. 27, 1910 1,497,946 Schmidt June 17, 1924 2,131,811 Kittredge Oct. 4, 1938 2,405,932 Alderman Aug. 20, 1946 2,557,448 Mathisen June 19, 1951

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