Patent GB-1305613-A (GB)
IPC: F02K3/10
Filed: 1970-11-25
Abstract: 1305613 Re-heat fuel systems BENDIX CORP 25 Nov 1970 [15 Dec 1969] 55955/70 Heading F1J A system for distributing pressurized fuel to one or more manifolds located in an engine combustion chamber, e.g. the re-heat chamber of a gas turbine jet propulsion engine, comprises a source of pressurized fuel, a fuel metering device, and a distribution valve connected to each manifold, each distribution valve being connected both to the flows of unmetered and metered fuel and having a first position in which all fuel communications to the associated manifold are disestablished, a second position in which the flow of unmetered fuel is communicated to the manifold to fill it up, and a third position in which the flow of metered fuel is communicated to the manifold, and in that control means comprising a positionable lever, valve means and fluid flow responsive means are provided for controlling the power output of the engine and for actuating the distribution valves from the first to the second and third positions in a predetermined sequence. Fig.1 shows a general arrangement of the system for supplying fuel to re-heat manifolds 22, 24, 26, 28 via a distribution assembly 38. The latter receives at pressure P 1  through duct 43 unmetered fuel from the output of pump 32 and at pressure P 2  through duct 36 fuel which has been metered by a valve 41 controlled by engine power control lever 42 and other signals. A duct 46 supplies fuel at pressure Pi for servo purposes to distributor 38 and fuel can return from the latter through duct 44 to the pump inlet at pressure P 0 . The distributor 38 comprises, Figs.3, 5, a casing 280 having an inlet 282 connected to the unmetered fuel in duct 43 and an inlet 284 connected to the metered fuel in duct 36, the inlets 282, 284 respectively communicating with ducts 302, 304. The latter can communicate, according to the position of valve mechanisms 294, 296, 298, 300, with outlets 286, 288, 290, 292 connected respectively to manifolds 22, 24, 26, 28. During non-re-heat operation the slide 360 of each valve 294 &c. occupies its lowest position under the action of spring 372, to close outlets 286 &c. and lever 42 is in the full line position. To select maximum re-heat, lever 42 is moved to the dotted position to energize pump 32 and metering valve 41. Simultaneously a solenoid 410 of valve 294 is activated by contact 264 causing a ball valve 406 to move upwards to a position in which duct 402 at P 1  is blocked and chamber 386 above slide 360 is vented to duct 404 at P 0  via port 396 in the slide and restriction 400. Slide 360 thus rises under the action of P 1  and jet pipe pressure P B  acting respectively against slide portions 364, 362, thereby registering slide ports 380 with ports 308 in communication with unmetered fuel duct 302. Fuel thus flows from the latter through outlet 286 to manifold 22, causing a drop in pressure at the throat of a Venturi 314 which, in turn, is applied via duct 340 to chamber 338 below a piston 336. The latter is sealed to a spring loaded bellows 332 the interior of which is subjected through duct 334 to jet pipe pressure P B . Thus piston 336 moves downwards causing ball valve 346 to close duct 354 at P 0  but communicating chamber 326 below piston 322 to duct 352 at P 1  so that piston 322 rises to fully open fuel valve 318 and speed the filling of manifold 22. When the latter is full, the decreased flow through Venturi 314 and corresponding rise in throat pressure causes piston 336 to rise so that ball valve 346 opens duct 354 at P 0  but closes duct 352 at P 1 . Thus piston 322 moves downwards causing valve 318 to close and simultaneously closing switch 434 to activate a solenoid 430 which moves a ball valve 426 upwards to close duct 422 at P 1  but open duct 424 at P 0 . The pressure in chamber 386 above slide 366 of valve 294 thus decreases causing the slide to rise until it engages stop 374. In this position metered fuel at P 2  is supplied through duct 304 and ports 312, 380 &c. to manifold 22. Simultaneously a recess 438 in slide 366 connects chamber 444 at P 1  with duct 440 and pressure switch 442 so that the latter closes to complete the circuit through lead 450 and activate solenoid 410 of valve 296 to initiate filling of manifold 24 with unmetered fuel via duct 302 and ports 308, 380 &c. Valve 296 operates in the same manner as valve 294 and when manifold 24 is full valves 298, 300 operate in sequence to control filling of manifolds 26, 28 respectively. Pressure switch 442 of valve 300 may be  connected to the fuel metering device 40 to provide a signal when all the manifolds have been filled. In a modified system Figs. 2, 4 (not shown), single Venturi 314 is replaced by two Venturis (66, 72) in parallel and of respectively lesser and greater flow area. Each Venturi (66 or 72) is associated with a fuel valve (64 or 70) corresponding to valve 318, the two valves (64, 70) being pivotally connected to a beam (88) via rods (74 or 76). In this arrangement manifolds 22, 24 are of greater volumetric capacity than manifolds 26, 28, the latter being sequentially filled with unmetered fuel via the small Venturi (66) and valve (64) and the former being sequentially filled via the larger Venturi (72) and valve (70). A piston (92) pivotally engaging one end of the beam (88) controls the changeover from valve (64) to valve (70).