US3587231A - Sequencing mechanism for a fuel control - Google Patents

Abstract

BY A SEQUENCING CONTROL, FUEL IS SEQUENTIALLY FED TO A PLURALITY OF NOZZLES DISPOSED AT DIFFERENT STATIONS IN AN ENGINE. THE SEQUENTIAL CONTROL INTERCONNECTS THE NOZZLES WITH METERED FUEL FROM A MAIN FUEL CONTROL IN A PREDETERMINED MANNER IN RESPONSE TO POWER LEVER POSITION ONCE THE NOZZLES ARE FILLED FROM ANOTHER SOURCE OF FUEL.

Description

United States Patent [72] Inventors George A. Fisher Appl. No. Filed Patented Assignee CONTROL 5 Claims, 3 Drawing Figs.

Int. Cl. F02; l/06 Field of Search 60/3928,

Saugus, CellL;

Charles F. Stearns, East LOIIIIIIQIIIOW, Mus.

June 26, 1969 June 28, 1971 United Aircraft Corporation East Hartford, Conn.

seousucmc MECHANISM FOR A FUEL n 13,ss1,231

References Cited UNITED STATES PATENTS 5/1950 Redding 60/261X 1]] 956 Crim 60/ 39.74U'X 2/1957 Karen 60/39.74X 2/1966 Rogers et al.'. 60/237 2/ 1966 Andrews 60/241X 1119.68 Rimmer 60/237 Primary Examiner-Al Lawrence Smith Attorney-Norman Friedland ABSTRACT: By a sequencing control, fuel is sequentially fed to a plurality of nozzles disposed at different stations in an engine. The sequential control interconnects the nozzles with metered fuel from a main fuel control in a predetermined v manner in response to power lever position once the nozzles are filled from another source of fuel.

PATENT EU uues um SHEET 1 UF 2 M? 1 Jill? INV ENTORS GEORGE A. FISHER CHAR? FSTEARNS BY M)! ATTORNEY P= PRESSURE PATENTEUJuuza l9?! SHEET 2 [IF 2 FIG. 3

SEQUENCING MECHANISM FOR A FUEL CONTROL CROSS-REFERENCES TO RELATED APPLICATIONS This invention is related to US. application entitled Sequential Fuel Control" Ser. No. 836,827 filed June 26, I969, by D. E. Anshutz and K. L. Linebrink and assigned to the same assignee.

BACKGROUND OF THE INVENTION This invention relates to fuel controls and particularly to sequencing mechanism serving to connect the metered fuel to a plurality of nozzles in a predetermined manner.

As is well known in certain types of jet engines it is customary to mount a plurality of nozzles at various locations in the combustion section to optimize combustion efficiency and it is desirable to sequentially feed these nozzles with fuel in a predetermined pattern such that certain segments of nozzles are fed with fuel prior to feeding the other segments. Thus, the purpose of the control is to provide proper sequencing of fuel fiow to the nozzles filling said nozzles prior to distributingthe proper metered fuel flow thereto.

SUMMARY OF INVENTION A primary object of this invention is to provide a segment sequence control for delivering fuel to combustion sections of a turbine type of power plant. It is to be understood that what is meant by combustion section is any station where combustion occurs; this includes within the ducts of bypass types of engines, afterbumers and the like.

A still further object of this invention is to provide in a sequential control means for filling the nozzles and their connecting line with fuel from a source of fuel prior to delivering metered fuel to said nozzles.

A still further object of this invention is to provide in a sequential control means for coordinating the filling with fuel a plurality of burner segments in a predetermined sequence in response to a remotely mounted power lever of an aircraft with the ability to select the number of segments desired and to provide for the cutting off of fuel in a predetermined manner.

Other features and advantages will be apparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration, partly in sectional, showing the details of this invention.

FIG. 2 is a schematic illustration showing the sequence control distributor valve connected to the segments in the burner section of a bypass of a jet engine partially shown.

FIG. 3 is another schematic illustration showing another embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 'many lines as there are nozzle segments and the number of pipes and nozzle segments not being limited but depending rather from the design criteria of the particular engine. Distributor valve to comprises a rotary valve element l9 having a central bore 2! formed therein communicating with a radial passage 32 adapted to selectively register with a plurality of circumferentially spaced ports 3 36, 38, d0, 42, and M. In addition, an arcuate slot is formed therein having sufficient area to span the entire arc of ports including 34 through 44, inclusively. Thus, rotation of valve element will first place radial passage 32 in line with 34 for receiving fuel from a separate source to be described hereinbelow prior to communicating with passage 50 defined by the arcuate slot 52 formed in the rotary valve element. Rotation of the valve element to the next port 36 places in communication the port 34 and the annular space 50 to which is fed metered fuel as will be described hereinbelow.

Therefore, from the foregoing, it is apparent that selectively positioning the radial passage 32 to register with radial passages 34 through 44 inclusively will first place fuel from a separate source to fill the lines communicating with the respective ports prior to placing the metered fuel evidenced in the chamber defined by the arcuate slot 52 for delivering metered fuel to the respective segments of the enginess combustion chamber. As noted from FIG. 1, metered fuel is admitted to the distributing valve through drilled passage 60 and into chamber 50 for selectively being admitted to the various flow lines interconnecting ports 34 through 44 inclusively and the burner segments.

The fill flow which is fuel pressurized by the fuel pumping system is admitted to fill fiow shutoff valve 70 via line 72, valve 70 serving to assure that the fuel is not admitted into the system until actuated by the latching mechanism generally indicated by reference numeral 144 consisting of valves 142 and M3. As noted from FIG. I valve element 74 moves against the compression spring 76 and the pressure in chamber 71 delivering fuel to the fill flow throttle valve generally indicated by numeral 78 via line 80 and pressure regulator generally indicated by numeral 82. The shutoff valve will be described in more detail hereinbelow. The pressure regulator serves to maintain the pressure drop across the metering orifice 84 at a constant value, which is dictated by the force of spring 86. The valve operates by sensing upstream and downstream pressure across metering orifice 84 by admitting upstream pressure to act on one face of valve element 88 and downstream pressure to act on the opposing face of element 88, pressure being admitted thereto respectively via passages 90 and 92. Since the area is equal, the force created by spring 86 acting in concert with downstream pressure urges valve element 88 to open valve metering element 93 with respect to the valve seat 94. This force is counteracted by the force acting on the underside of valve element 88. When the total force of the pressure on the upperside of valve element 88 and spring 86 counterbalance the force acting on the underside, the pressure drop (A P) across metering orifice 84 will be equal to the force of spring 86. Any deviation from the balance will adjust valve element 88 until the A P is returned to its selected value.

Fuel admitted into orifice 84 passes through an axial drilled passage 96 formed in the fill flow throttle valve 98 and communicates with radial passage 32 formed in the rotating distributing valve element 19.

From the foregoing it is apparent that the rotary distributor valve element 19 serves to fill the one line interconnecting the burner segment with fuel delivered from one source and then proceeds to fill the next adjacent segment, which fuel being metered from the main fuel control, shown in blank, enters the fuel section to deliver metered fuel to that particular connecting segment ring just filled. By contouring orifice 84 as shown, it is possible to select the rate at which each segment will fill. It is understood, as is obvious to one skilled in the art, that the outer window (orifice) cooperating with the inner window has a fixed metering area and the total metering area will be dictated by the portion of the windows that is exposed to the fuel flow.

The next portion of the description will describe the actuation of the rotary distributor valve I9. As noted from FIG. I, the fill flow throttle valve 98 is connected to the rotary distributor valve I) by an axial hollow shaft I00. Shaft I00 carries pinion gear I02 which is in muting relation to the rack gear I04, the details of both being eliminated for the sake of convenience as any means of actuation will fall within the purview of this invention. The rack gear 104 is made integral with the connecting shaft 106 interconnecting the pistons 108 and IE0. Fluid admitted to these pistons serves to position them with a consequential movement of the rack 104 and a likewise rotary movement of the distributor valve 19. This movement is made in response to the power lever generally indicated by numeral 112 which serves to control the power lever servo 136 and the cooperating cam 172 which, in turn, schedule the segments in a predetermined manner but assuring that the fill is manifested before the various burner segments are connected to the metered fuel. Power lever adapted to be positioned for admitting fuel to the segments is connected to cam 114 via the schematically illustrated connection 116. Cam 172 is adapted to schedule one or all of the segments in sequential order and by moving it to the extent of its travel which will be the high point of the node, follower 118 is forced upwardly causing the pilot valve 120 to move in an upward position. As would be obvious to one skilled in the art, cam 172 can be used to adjust the fuel control so as to properly schedule metered fuel flow with the actuated segments. The lands on valve 120 uncover ports 122, 124 and 126 for communicating high pressure line 128 with line 130 for admitting pressurized fluid into chamber 132 of piston actuator 134. However, piston 136 will remain stationary until fluid present in chamber 138 formed on the back side of piston 136 is drained. Draining of this chamber is effectuated by latching mechanism 144. As can be seen from the drawing, latching mechanism 144 is connected to the lever 146 and serves to open chamber 138 to drain by positioning valve element 142 downwardly. Hence, piston 136 will remain stationary notwithstanding the admittance of pressurized fluid in chamber 132 until line 152 is connected to drain via line 140, pilot valve 120, and drain connection 139.

The latching mechanism 144 is controlled by fill sensor generally indicated by numeral 156. The fill sensor measures the fluid being admitted to the various fill lines and responds to the fluid in the line communicating with the source of fill fluid. While the particular means for sensing when a segment line is filled does not form a limitation to the invention, in this instance the fill sensor measures the pressure drop across orifice 84 and when that approaches zero, the flapper valve 158 will shut off the flow from orifice 160 to build up the pressure downstream of restrictor 162 which ultimately is admitted into actuator 164 via connecting line 166. Thus, when the pressure drop across orifice 84 is at zero, pressure is admitted behind piston 168 urging it against spring 171 in a downward direction for positioning lever 146 downwardly and with a like movement of valve element 142 being connected thereto by the pin connection 170. This movement interconnects line 152 with line 140 for draining chamber 148. Piston 136 is then urged upwardly and by virtue of the rack and pinion connection generally indicated by numeral 173 causes the power lever servo cam 172 to rotate and position valve element 174 upwardly. Lever 146 abuts against the projecting pin 176 and since it is moved upwardly likewise lever 146 also moves upwardly repositioning valve element 142 to the closed position and hence latching the system until the next segment is filled.

As noted, the fill sensor 156 consists of piston 180 having one surface exposed to pressure upstream of orifice via line 182 and the other surface to pressure downstream of orifice 84 via line 184. Hence, the pressure acting across orifice 84 and the force of spring 181 is felt by piston 180 and moves flapper 154 relative to orifice 160 by virtue of the connecting rod 188. High pressure discharging from 160 is normally dumped to drain (i.e. pump inlet) via port 190 so that closure of flapper valve 158 builds up pressure downstream of orifice 162 disposed in line 192 which in turn is transmitted to chamber 164 via line 166 and the Most selector valve 194.

Thus, from the foregoing, it is apparent that the admittance of pressure into chamber 132 and the dumping of pressure from chamber 148 permits piston 136 to move axially for rotating cam 172. The cam motion is picked up by follower 200 suitably attached to the lever 202 which is also pinned to the pilot valve 120 by pin 204. This feeds back the signal to the pilot valve to return it to its null position such that the lands 122, 124, 126 are in line-on-line with the respective ports which will occur only when the signal scheduled by the pilot lever 112 as seen on cam 114 is matched by the number of segments actuated. Thus if the power lever is positioned to fill the six segments, then the null position will be reached solely when the six segments are filled.

in addition, the motion of cam 172 is also picked up by follower 208 which is suitably connected to fulcrumed lever 210 having one end bearing against spring 212 disposed on the top surface of pilot valve 214. Pilot valve 214 serves to position pistons 108 and 110 for controlling movement of the segment distributor valve 19. This is effectuated by applying a pressure signal to chamber 216 via drilled passage 218 and line 220. This is accomplished by controlling the pressure drop across fixed restriction 222 disposed in line 220 which is in communication with regulated pressure discharging from the pressure regulator indicated in blank by reference numeral 224 which is fed by pump 226 in communication with reservoir 228. As noted from FIG. 1, the branch line 230 downstream of fixed restriction 222 feeds into chamber 232 which has disposed therein bellows 234. Formed on the free end of the bellows and centrally disposed thereof is orifice 236 which is in proximity to the projection 238. Movement of the bellows 234 positions orifice 236 relative to projection 238 for effectuating closure thereof. The bellows is controlled by the push rod 240 which is urged against cam 242 attached to the hollow shaft 100. Rotation of the hollow shaft rotates cam 242 to position push rod 240 relative thereto and for each position of cam 242 there will be a corresponding position of orifice 236 and likewise there will be a corresponding pressure in chamber 216 for positioning the land of spool 214 relative to the various ports. Thus, high pressure admitted into port 250 is either directed to line 252 or 254 depending whether the spool has been moved upwardly or downwardly. lf 252 is connected to high pressure, then 254 is connected to drain via line 256. Conversely, if high pressure is admitted to 254, then line 252 is connected to drain via line 258. Lines 252 and 254 are in communication with the ends of pistons and 108 respectively, for effectuating movement thereof. The force of the pressure acting on the end of spool 214 created by the pressure in chamber 216 is counteracted by the force produced by spring 212. When these forces are balanced, no movement of pistons 108, 110 will occur. Accordingly, for each position of rotary distribution valve 19 there will be a corresponding position of cam 242 and a likewise corresponding position of lever 210 and pilot valve 214 will be at the null position.

To effectuate closure of the various segments, the pilot lever is returned to its original position rotating cam 114 to the lower point imparting an unbalance to lever 202 with a consequential downward movement of pilot valve 120. This positions lands 122, 124, and 126 downwardly to uncover the various communicating ports for applying high pressure from line 128 to the Most selector valve 194 via line 260. This moves the ball 262 downwardly to block off flow from line 192. Piston 168 moves downwardly for disanning the latching mechanism 136 by a consequential downward positioning of valve element 142. High pressure is then applied from line 266 into line 140 by land 126 for applying high pressure into chamber 138 via the latching valve 144 and line 152 urging piston 136 downwardly for rotating the power lever servo cam 172 by the rack and pinion mechanism generally indicated by numeral 173. Pilot valve is continuously urged in a downward direction by action of spring 272. Obviously, rotation of cam 172 in a downward direction will cause an unbalance on spring 212 by the movement of lever 210. As the load decreases by rotating lever 210 counterclockwise, the pilot valve will move so that the lands are positioned to communicate the pressure behind piston 110 and the pressure behind piston 108 so that it will move in a decreasing direction. It will continue to move until the scheduled signal imposed by cam 114 is satisfied. Any number of nozzles can be shut off in a descending manner. Thus, movement of power lever if advanced, initiates the various segments sequentially in an ascending order and if retracted, turns off any given number of segments in a descending order.

OPERATION OF THE SEQUENCE SEGMENT CONTROL Assume the pilot is calling for the full number of segments to be turned on, he will advance the pilot lever to the full open position. This, in turn, rotates cam 114 to the high point creating an unbalance on fulcrum lever 202 for positioning the pilot valve 120. This, in turn, admits high pressure servo fluid into the pilot lever servo piston 136 for urging it upwardly. Since chamber 148 is filled with fluid, the piston will not move until this fluid is dumped. Dumping of fluid from chamber 148 is effectuated by actuating the latching mechanism 144 by unseating valve 142 in response to the fill sensor 156 sensing fill line 96 by measuring the pressure drop across orifice 84. When the line is filled, i.e., when the A P across 84 is substantially zero, and this will occur since the pressure drop is being felt across the nozzles when the line is filled, this signal is transmitted to latching servo 164 by closing off the flapper orifice 160 with flapper element 158. As noted from FIG. I, the pressure drop is measured across the fill flow shutoff valve 74 and in line pressure regulator 82 inasmuch as this is an indication of the A P across orifice 84. As would be obvious to one skilled in the art, any other pressure indicative of A P across orifice 84 can be utilized. This, in turn, allows the pressure in line 192 to increase and this pressure is in turn felt on the back side of piston 168 being in communication with line 166 which is in communication with line 192. Piston 168 moves down forcing lever 146 to pivot clockwise about pin I76 therefore carrying valve 142 downwardly to open up line 140 to line 152. Since land 126 has moved upwaRdly, drain line 139 communicates with line 140 for draining the fluid in chamber 148, and permitting the piston 136 to move upwardly for rotating cam 172 allowing lever 146 which is balanced by spring 280 to move to its latching position. The metering land of valve 284 serves to assure that the shutoff valve 74 is closed when the filling process is completed. Hence, once the line is filled with fuel from a separate source, say directly from the pumps, the distributor valve 19 is allowed to rotate so as to place metered fuel from the main fuel control in communication with the segment just filled. The rotation of the metering valve then places the radial passage 32 of distributor valve 19 in communication with the next line 36. Line 36 fills up in a similar manner and when it is completely filled, the pressure drop across 84 again becomes zero reactivating the latching mechanism 136 to allow the distributor valve to move in the manner just described above. Of course, the movement of the distributor valve is dictated by the position of cam 172 which controls the pilot valve 214 for applying and draining pressure from pistons I08 and 110 respectively, depending on whether the nozzles are filling or emptying.

Another embodiment of this invention is illustrated in FIG. 3 wherein the segment sequence control sequentially and automatically fills and communicates the nozzles and interconnecting passages with metered fuel in successive order until all of the burner segments are operative. As noted, the distributor valve generally indicated by numeral 300 comprises piston 302 disposed in one end of cavity chamber 304 and defining therewith chamber 306. Piston 302 carries an elongated hollow member 308 concentrically mounted to and extending beyond elongated tubular member 310 depending flange 312 defining an end cap and valve element is formed adjacent opening 314. When the sequential control is inoperative, fuel is recirculated from the pump and flows from inlet 316 through opening 314, the center passage 320, space 318, and passage line 319 which is, in turn, connected with the fuel pumping system, not shown. Upon actuation of piston 302 by draining fluid from chamber 306, piston 306 moves leftwardly so that valve element 312 seats against the end of member 310 blocking off the flow through center passage 320.

Movement of piston 302 leftwardly also moves the flange element 324 fonned on the end of member 308 which serves to interconnect line 319 with port 332 formed in the axial member 310 and places annular passage 334 into communication therewith for leading fuel from the pump to segment line 336 through opening 338. Further movement of piston 302 leftwardly positions opening 338 with the next adjacent nozzle line 340. This movement also moves the end flange 312 and valve element leftwardly to uncover line 336 exposing it to metered fuel evidenced in line 3l6 whi'ch, in turn, is delivered to the burner segments similarly to tha't'described in the above with reference to FIG. 1. Upon fillingnozzle 340, piston 306 moves to the next nozzle interconnecting it with fill pressure and communicating 340 with metered fuel. Piston 302 will continue its travel until all the nozzles are filled and communicated with metered fuel.

Control of distributor valve 300 is effectuated by the segment flow control valve generally illustrated by numeral 350 and the segment flow control valve generally indicated by numeral 352. The system is actuated by positioning pilot lever 354 which, in turn, rotates cam 356. Cam 356 actuates valve 358 for applying servo pressure into the end of segment control valve 350 via line 360. Segment control valve comprises a plurality of segmental pistons cooperating to push on push rod 364. Thus, applying pressure into chamber 366 urges segment 368 leftwardly because it abuts against the next segment 370 which in turn transmits a signal to push rod 364 which is rotary pinned to lever 380 by pin 400. Leftward movement of push rod 364 causes lever 380 to rotate counterclockwise about pivot 382 and consequently positions spool 384 which is pinned thereto by pin 386. Movement of spool 384 positions land 388 uncovering drain port 390 which drains chamber 306 via line 392. This moves valve element 324 to uncover port 332 for communicating pump pressure directly with the segment 336 via the opening 332, annular passage 334 and opening 338. As piston 302 moves to the position described in the preceding sentence, the piston feeds a signal back to pull valve 352 by lever 380.

As described above, when nozzle 336 is filled, the pressure in the line is sensed by pressure tap 396. This, in turn, is transmitted to a segmental piston of segment control vaLve 350. Each segmental piston has a similar pressure tap connection, serving to sense fuel pressure in the burner nozzles. The application of sensed fuel pressure adjacent segmental piston 370 into segment control valve positions it leftwardly to move push rod 364 to the left for repositioning segment flow control valve 352 to uncover port 390 for further draining chamber 306 as was described above. Nozzle 336 will now be directly connected to metered fuel (from the main fuel control) evidence in line 316 and simultaneously interconnecting the next segment 340 with opening 338 for filling from the pump. This continues until all of the segments are placed in communication with the metered flow subsequent to being filled.

As noted, when piston 302 moves leftwardly, it pivots about connecting pin 400 urging the spool 384 of the segment flow control valve 352 to the right for returning the spool back to its line-on-line position. Thus, the segment flow control valve is always returned to its null position upon movement of the piston 302 to the desired location, assuring-that the nozzles are not connected to pump pressure until the previous nozzle has filled as sensed by the individual pressure taps.

It should be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the spirit or scope of this novel concept as defined by the following claims.

We claim:

1. A fuel control for a turbine type of power plant having a burner section including a plurality of burner segments disposed along various stations thereof, a power lever, means for delivering metered fuel to said various burner segments and means for filling said burner segments with fuel other than the metered fuel, sequential control means responsive to said power lever and the pressure in said burner segments for controlling said filling means for filling each of said burner segments in a successive predetermined pattern and for controlling said delivery means for delivering fuel to each of said burner segments in a successive predetermined pattern solely upon the filling of said burner segments by said filling means,

said sequential control means including a servo actuated piston having a fluid reaction chamber, means for admitting servo fluid into said chamber for imparting rectilinear movement thereto, an elongated hollow member extending axially in a cavity from the side of said piston opposite said chamber and carried thereby, the end of said elongated hollow member sealing fuel fed into said cavity from egressing into the hollow portion of said elongated member when in the operative condition, a plurality of ports communicating with said burner segments for admitting metered fuel therein, a tubular member having an annular passageway formed therein concentrically mounted about said elongated hollow member, means for admitting fill fuel therein through a radial opening formed in said tubular member so as to flow fill fuel through the annular passageway through the radial opening to one of said ports, and said radial opening being in spaced relationship to said end of the elongated hollow member so that said opening registers with said ports prior to permitting metered fuel in said cavity to egress into said ports.

2. A fuel control as claimed in claim 1 including servo control means having a pilot valve for regulating the flow of servo fluid into and out of said fluid reaction chamber, and sensor means including means for connecting said fluid reaction chamber to said pilot valve for measuring the condition in dicative of the presence of fuel in said burner segment for positioning said pilot valve 3. A fuel control as claimed in claim 2 including feedback means interconnecting said servo actuated piston and said pilot valve.

4. A fuel control as claimed in claim 2 wherein said feedback means and said connecting means include a lever having one end pivotally connected to said servo piston, the other end pivotally connected to said pilot valve and said sensor being pivotally connected therebetween.

5. A fuel control as claimed in claim 4 wherein said sensor means includes a casing, a plurality of piston segments each having a separate fluid receiving chamber, and pressure taps communicating each of said burner segments with each of said fluid receiving chambers for positioning said piston segments upon reaching a predetermined value.

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