Patent GB-736797-A (GB)
Title: Improvements in or relating to fuel systems of prime movers
Inventor: MARTIN WILLIAM ALEXANDER ONSLO
IPC: F02C7/22
Filed: 1952-06-16
Abstract: 736,797. Gas turbine plant. ROLLS-ROYCE, Ltd. July 22, 1953 [June 16, 1952], No. 15164/52. Class 110 (3). [Also in Group XXIX] The fuel supply to a gas turbine engine is controlled by a device comprising a nozzle fed with fuel under pressure by a pump, a receiving chamber connected to the fuel injector means and having an inlet, in the path of the fuel jet from the nozzle, which is arranged to convert the kinetic energy of the fuel jet into pressure in the receiving chamber, and an obturator adjustable across the path of the fuel jet to vary the amount of fuel entering the inlet and a spill passage to take away the fuel intercepted by the obturator. The high pressure pump 10 supplies fuel from a tank 11 to the burners 12 through a control device 13. The control device comprises a cylindrical body 14 having a duct 15 which leads to a distribution chamber 16, the fuel from which is discharged through nozzles 18 across an annular channel 17 formed in the end face of the body 14. The body 14 also has an annular channel 19 which is con-. nected to the channel 17 by a pair of outwardly diverging radial passages 20, each of which is aligned with one of the nozzles 18. The fuel for the nozzles 18 thus tends to flow into the passages 20. An obturator 23, in the form of a drum having one edge which projects into the annular channel 17, is actuated by means responsive to engine speed. In the arrangement shown, a permanent magnet 26 located inside a drag cup 27 is rotated by the engine, and the drag cup is connected through a reduction gear train 28 to the spindle 24 of the obturator 23. The obturator 23 is thus moved against the acton of a spiral spring 25 so that it has a unique position for each speed. The edge of the drum 23 is profiled, Fig. 2, so that it cuts off more or less the fuel issuing from the nozzles 18. In the arrangement shown, the profile of the edge is repeated for each nozzle 18 and comprises a starting portion 23a, 23d, accelerating portions 23b, 23e and top speed portions 23c and 23f. The nozzles 18 are substantially uninterrupted by the obturator in the starting position, partly interrupted in the accelerating position and on approaching the top speed condition are again substantially uninterrupted. The portions 23c, 23f are arranged to cut off the jets sharply if the top speed is exceeded. A spill passage 29 returns the fuel cut off by the obturator to the suction of the pump 10. If a number of jets and receiving chambers are provided, the receiving chambers may be connected to a manifold and the obturator so formed that some of the jets are totally obturated and rendered inoperative to obtain steady running at maximum speed. In this arrangement, a non-return valve may then be provided, to prevent reverse flow from the manifold through the receiving chambers to the obturator space when a receiving chamber is cut out of operation. As the torque required to move the obturator varies to the extent to which the jet is interrupted, the obturator may be arranged to be in the maximum torque position relative to only one of the jets at a time.