Patent GB-1040433-A (GB)
Title: Group thrust compensator for an installation comprising a plurality of jet lift engines
Inventor: ELLIS STAFFORD MALCOLM
IPC: B64C29/00
Filed: 1963-05-01
Abstract: 1,040,433. Vertical lift jet engine plant. ELLIOTT BROTHERS (LONDON) Ltd. April 28, 1964 [May 1, 1963; June 7, 1963], Nos. 17256/63 and 22687/63. Heading F1J. [Also in Division B7] The invention relates to a group thrust compensator for correcting for distrubance of the lift thrust of a group of jet engines caused by the deterioration or failure of operation of one or more engines and comprises at least one fluid pressure responsive device, a movable member or members in the device, means for balancing fluid pressure from each engine corresponding to the lift thrust thereof when in operation against the fluid pressure derived from a different engine so that upon unbalance in the pressures occurring, movement of the movable member takes place and means associated with the movable member are arranged so that a reduction in the fluid pressure derived from one engine causes the throttle openings to be varied. One fluid pressure responsive device is shown in Figs. 1, 2 and 3 and comprises a housing 11 having a cylindrical internal chamber within which a member 18 is mounted for angular rotational movement. The cylindrical chamber has two radially inwardly extending walls 20 which project to the outer surface of the rotary member. The rotary member has two radially outwardly extending vanes 19 which project to the inner surface of the cylindrical chamber. In this way four pressure chambers 21, 22, 23, 24 are provided, the chambers being of equal volume when the rotary member is in the position shown. Hydraulic pressure which is proportional to the thrust developed by jet lift engines is applied to the chambers, fluid pressure from one engine for example being supplied through a pair of pipes to two inlets 25, 26 thence through an automatic selector valve 28 and duct 31 to the chamber 23. A rotary disc member 51 is secured to the shaft 17 of the rotary member 18, the rotary disc having on its inward face a pin 55 on which is mounted a roller 56, the disc having on its outer face a pin 59 which is connected by means of linkage to the throttle controls of the lift engines. A pair of arms 44, 45 is pivotally mounted on pins 46, 47 secured to the fixed housing 11 of the device, the arms being held towards each other by means of a spring 48 so that the faces 57, 58 on the arms in the position shown in full lines in Fig. 3 bear against the roller 56 carried by the rotary disc 51, also against the hub portion 52 of the rotary disc. Should one of the lift engines fail, the pressure indicative of the thrust of that engine will fall so that the pressure in say the chamber 23 will fall, the rotary member 18 will rotate in a clockwise direction and with it the rotary disc 51 and roller 56, the roller 56 and the arm 45 moving to the positions indicated in chain dotted lines at 56b and 58a. The pin 59 will also be moved whereby the throttle levers of the remaining engines are moved so as to increase the thrust of these engines. One arrangement is shown in Fig. 4, four lift jet engines being indicated at 60, 61, 62, 63 and the fluid pressure responsive device at 75. The pin 59 on the rotary disc 51 is shown in Fig. 4 and a lever 88 is mounted thereon, one end of the lever being connected by rod 90 to the throttle control lever 91, and the other end of the lever being connected by rod 89 and further links to the engine throttle levers 68, 69, 70, 71. The hydraulic pressure connections from the engines to the device 75 are shown for example at 76, 77. The positions to which the pin 59 may move in the event of failure of engines are indicated at 59a and 59b the corresponding movements of the linkages and throttle levers being indicated in chain dotted lines. The lever 88 may be locked in position while the engines are being started one by one so as to prevent the device 75 from acting at this time. A locking means may also be provided to lock the rotary disc 51 in position after one engine has failed so as to avoid the possibility of the disc being moved back to the neutral position in the event of failure of a second engine. The adaptation of the invention in the case of various combinations of engines are described; thus in Fig. 10 one large engine 122 and three smaller engines 123, 124, 125 are utilised; two pressure responsive devices 126, 127 are required and these are shown diagrammatically. The pressure fluid line from the large engine 122 is connected to one chamber of the device 126 and one of the smaller engines 125 is connected to a second chamber of the device 126, the areas of the two chambers being different as shown. A second of the smaller engines 123 is connected to a pair of opposed chambers of the device 127, the third of the smaller engines is connected to a third chamber of the device 127, and the first of the smaller engines 125 which is connected to a chamber of the device 126 is connected also to the fourth chamber of the device 127. In Fig. 11 is shown a second form of pressure responsive device, this embodiment comprising a pair of pistons 144, 145 mounted on rods 148, 165 in two cylinders 146, 147 disposed side by side, the pistons and cylinders forming four chambers 171, 172, 173, 174 to which pressure fluid is supplied from jet lift engines so as to indicate the thrust thereof. A yoke member 160 is urged into contact with the piston rods 148, 165 by means of a spring 163 acting against an abutment 162 on the shaft 161. If the engine associated with say the chamber 171 should fail, the piston 144 will be moved to the left and so also the yoke 160 and with it the pin 175 on which the bell crank lever 176 is mounted, the lever 176 acting through linkage to open the throttles of the remaining engines. Should the pressure in the chamber 172 fall, the piston 144 will move to the right and the piston rod 148 will act on the link 168 which is pivotally mounted at 167 so as to urge the piston rod 165 to move to the left, the movement of the piston rod causing movement of the yoke 160 as before. A further embodiment is shown in Fig. 12 in which four pistons 182, 183, 184, 185 are disposed in cylinders 178, 179, 180, 181, the piston 185 being of smaller diameter and longer stroke than the other pistons. The piston rods of the four pistons are connected to a common crosshead 198 which is connected to a rod 211 and is loaded by a spring 196. Fluid pressures representative of engine thrust are applied through lines 199, 200, 201, 202 to the four cylinders while tappings are taken from three of the lines 199, 200, 201 through metering orifices 204, 206, 208 to a common chamber 194, pressure fluid in which acts upon the sides of the pistons opposite those upon which pressures from the lines 199, 200, 201, 202 act. A leak device 209 is provided from the chamber 194. The pressure in the chamber 194 is related to the mean tapped engine pressure. The object of this arrangement is to ensure that the device will not operate in the event of an upward engine failure (i.e. of an engine running away).