Patent GB-1071243-A (GB)
Title: Fuel supply and power control device for a gas turbine jet engine
IPC: F02K3/10
Filed: 1964-08-05
Abstract: 1,071,243. Gas turbine jet engine fuel systems. BENDIX CORPORATION. Aug. 5, 1964 [Sept. 13, 1963], No.45915/66. Divided out of 1, 071, 241. Headings F1G and F1J. [Also in Division G3] The invention relates to a fuel supply and power control device for a gas turbine jet engine having exhaust reheat combustion equipment and a variable area propulsion nozzle, the device comprising a reheat control device adapted to control flow of reheat fuel according to the position of a reheat control member operatively connected to a motion transmitting means responsive to the engine control lever and a propulsion nozzle area control mechanism the control member 454 of which is operatively connected to and actuated by the motion transmitting means, the control members being both connected to and actuated by a nozzle area and fuel flow correlation three dimensional cam 474 the position of which is controlled as a function of the area of the propulsion nozzle through linkage 75, 74 and the fluid pressure ratio across the gas turbine as sensed by the bellows 492, 499 so as to effect a co-ordinated modification of propulsion nozzle area and reheat fuel flow. The reheat control device includes a fluid pressure actuated shut-off valve 338 Fig. 4 the pressurization of which is controlled by movement of the spool valve 622 Fig. 5 effective to close off or open line 449 to drain pressure, the valve 622 forming part of the motion transmitting means responsive to control lever position 54. The delivery of pump 77' of the variable area nozzle control is connected through line 368 to a spool valve 454 whereby servofluid is caused to flow either to line 457 or to line 458 and so to one side or the other of the piston 65 which controls movement of the nozzle members 27; thus upward movement of the spool valve 454 causes servofluid to pass to the line 457, the line 458 then being connected to return line 459 back to the pump inlet. The position of the spool valve 454 is controlled by a servovalve 470 the spool valve following the movement of the valve 470 which is mounted at one end of a lever 471 which is pivotally mounted at its mid point on a rod 472 which moves axially in dependence on movement of a valve member 563, the opposite end of the lever 471 being controlled by a threedimensional nozzle area and fuel flow correlation cam 474 which is mounted on a shaft 475. The shaft 475 is rotated as a function of propulsion nozzle area by means of pulley 74 which is connected with the nozzle actuator 65 and with the shaft 475 through gearing 476. The shaft 475 is moved axially as a function of the pressure ratio P T4 /P T7  across the turbines 33, 30 by means of a lever 477 pivotally mounted on rod 478 of servopiston 479 and pivotally connected at its other end to rod of piston 633. Servofluid at pressure P R  is supplied to the right hand side of piston 479 at a predetermined high compressor speed N 2  from the main fuel control through passage 480, spring- loaded spool valve 481 which is actuated by cam 482, passage 483, a two-position spool valve 484 and passage 228 (see also Fig. 2). The pressure drop across piston 479 is controlled by servovalve 488 which is actuated by bellows 492 which is connected to pressure P T4  upstream of the turbine 33 through passage 493. The lever 489 of the servovalve 488 is controlled also by bellows 499 which is connected to pressure P T7  downstream of turbine 30 through passage 500. The roller 495 between the levers 489 and 496 is carried by a follower 502 which is urged into contact with cam 482 the angular position of which is controlled by a servopiston 506 to the lower side of which servofluid at pressure P R  is communicated through lines 483, 508. Servofluid discharges from the upper side of the piston 506 through line 510 which terminates in an outlet 513 controlled by a pivoted valve 514 (see Fig. 2). The lever 514 is controlled by bellows 515 the interior of which is connected by line 524 to the interior of bellows 523 in the nozzle control Fig. 5. The servopressure in line 524 is controlled by the position of valve 526 in bellows 523 with respect to the tubular member 527. The movable end of the bellows 523 is carried by lever 528. The lever 528' adjacent lever 528 is controlled by bellows 538 which is connected to servofluid line 483 by restricted line 539. The line 539 is also connected to line 540 which leads to passage 541 in a lever member 542 the outlet from line 541 being controlled by servovalve 543 which is held closed by means of cam member 545 until a predetermined throttle lever position 54 is attained. When this position is attained the valve opens and the line 541 is opened to drain pressure P 0 . The lever member 542 is pivotally mounted at 544 and a lever 547 is pivotally mounted on the lever 542. The lever 547 is pivotally connected at its other end to a ratchet member 548. A servovalve 555 carried by the lever 547 co-operates with the opening in stem 556 of servopiston 557 which is supplied at its upper and lower sides with servofluid at pressure P R . Upon selection of reheat, the lever 547 moves upwardly in stages controlled by the ratchet member 587 by spring 552 acting against lever 542, the ratchet being released in stages by means of spring-loaded piston 585, the stem 586 of which acts against pawl member 587. The piston 585 is acted on by servofluid supplied thereto through line 584 under control of valve 582. The servopiston 557 follows the upward movement of the lever 547 as does the valve member 563 integral with the servopiston. Upward movement of the valve member 563 causes upward movement of the rod 472 which in turn acts to close valve 470 so that spool valve 454 moves upwardly and causes the propulsion nozzle members to open. Upward movement of the valve member 563 also causes the spool valve 622 to move upwardly in steps thus venting the passages 449, 625, 626 in turn which results in the shut-off valves such as 338 in Fig. 4 opening whereby reheat fuel flows first to manifold 38, then also to manifold 39 and then also to manifold 40. Upward movement of the rod 472 also actuates the lever 615 to close the servovent 608 whereby the servopiston 604 moves downwardly thus rotating shaft 403 and cams 402, 451 and 452 mounted thereon which acts to cause opening of the reheat fuel metering valves 334 Fig. 4. In the event of reheat equipment blow-out, the reduction in pressure sensed by bellows 499 acts to open the servovent 488, the servopiston 479 moves to the left whereupon the bracket 580 moves the stop 644 to the left so that bell-crank lever 643 can pivot counterclockwise thus enabling valve 638 to move upwardly. Servofluid in line 639 can now pass through the chamber 637 to the line 636 which leads through line 635 to the space below piston 144 in the main fuel control Fig. 2. The resulting upward movement of the piston 144 swings the bell-crank lever 139 clockwise whereby the rod 131 is moved to the left thus causing servovent 116 to open and thus servopiston 109 moves to the left. The lever 107 pivots counter-clockwise about the abutment 111 and so the follower 106 moves to the right which results in the main metering valve 84 moving downwardly to restrict the fuel flow to the main combustion equipment. Flow of servofluid through the line 636 also acts to open ball valve 647 whereby servofluid passes through line 646 to the left hand side of piston 648 which moves to the right so connecting servofluid line 560 to drain pressure P o  through line 650. Fall of servopressure in line 560 causes servopiston 557 to move downwardly, the piston still being subject to servofluid pressure P R  at its upper side through lines 558 and 347 from line 346. Downward movement of the piston 557 causes the lines 626, 625, 449 to be closed off so that the reheat fuel shut-off valves 338 are closed in sequence. The spool valve 454 also moves downwardly so that the propulsion nozzle closes. Also the piston 604 moves upwardly since servofluid at pressure P R  is still passing through line 598 to the lower side thereof so that the shaft 403 and cams 402, 451, 452 carried thereby rotate to close the reheat fuel metering valves 334. A similiar result occurs should the linkage 74, 75 fail - the piston 640 moves downwardly so that servofluid in line 483 passes through lines 641, 655 and through valve 656 to line 646 to act at the left-hand side of the piston 648 as before. When the piston 648 moves to the right the line 652 is opened so that servofluid at pressure P R  from line 346 is now communicated to the piston 648. When the valve 563 has moved to the uppermost position so that full reheat is in operation the passage 564 in the valve places line 566 in communication with line 565 so that servofluid at pressure P R  flows through line 566 to the space 261 of the casing 260, Fig. 2 whereby the piston 262 moves to the left to the position shown so that follower 269 engages cam 233 and control of the cam 132 in an axial direction is thus transferred from cam 234 to cam 233. During non-reheat operation the spool valve 484 is in its left hand position, but when reheat is selected, the cam 673 actuates bell-crank lever 671 to close the vent 669 as shown whereupon the spool valve move to the right so that servofluid in line 228 (connected to line 228 Fig. 2) can now pass through annular groove 676 to line 483 and so pressurize the various servodevices in the nozzle control unit. The line 346 is supplied with servofluid from line 346 Fig. 3 during non-reheat as well as reheat operation.