Patent GB-808863-A (GB)
Title: Improvements in engine starter mechanism
IPC: F02N99/00
Filed: 1956-09-04
Abstract: 808,863. Engine starter mechanism. BENDIX AVIATION CORPORATION. Sept. 4, 1956 [Oct. 24, 1955], No. 27047/56. Class 7(5) In an engine starter mechanism comprising a starter jaw member operatively connected to driving means for axial movement into engagement with an engine jaw member and rotation therewith and means supporting the latter member and holding it in alignment with the starter jaw member, the supporting means include resilient means provided within the starter mechanism for resiliently anchoring the engine jaw member to an element of the mechanism so that the engine jaw member can move axially during engagement. As shown a turbine driven engine starter comprises a combustion chamber 1. Hot gases of combustion exit from the latter through nozzles 2 to drive a turbine member 3 carrying a drive shaft 4 which is rotatably supported in bearings 5, 6. A pinion gear 7 formed on the shaft 4 drives a ring gear 8 through idle gears 9. Pins 11 on which the idle gears rotate are carried by a bell member 12 having a shaft extension 14. A hub portion 15 of the extension 14 carries a sun gear 16 which through planetary gearing 17 rotatable in a surrounding fixed ring gear 18 and through trunions 19 supporting the planetary gears, drives a disc clutch barrel member 20. The barrel member rotates a spline nut 21 through a disc pack clutch 22. A cup member 33 serves in aligning the teeth of the starter jaw 23 with those of the engine jaw 27. Rotation of the spline nut rotates the starter jaw with it. A friction force applied by arcuate flyweights 36 carried in radial slots 37 in the cylindrical wall of the cup member causes the starter jaw to advance axially to the left as the spline nut rotates. Each flyweight is pivoted at one end on a pin 38 that is supported at its ends in the end walls of the slot. Projecting from the end wall of the flyweight is a centre pin 39, passing freely through a hole 41 in the opposite end of the flyweight is a pin 42, which pin is also supported at its ends in the walls of the slot. The hole 41 is of a slightly larger diameter than the pin extending through it and the wall of the hole limits the extent of angular movement of the flyweight. A leaf spring 43 inserted between the three pins tensions the flyweight angularly and normally to a position where one end of the weight is lowered slightly below the peripheral surface of the cup member and the opposite or pivot end 44 is raised slightly above this peripheral surface. The raised ends of the flyweights bear against the inner wall of the starter jaw and provide a frictional force against the latter which causes the starter jaw member to advance axially outward as the spline nut rotates. After the engine has started and as its speed increases centrifugal force forces the flyweights to pivot outward. By this action the pivot ends 44 thereof will be drawn away free from the inner surface of the jaw member and the opposite ends will, because of the limiting pin and hole, be held at the peripheral surface of the cup member, also free of the inner wall of the starter jaw. A plurality of pins 46 are located in sockets in the lands forming the separating walls between the slots in the cup member 33. These pins move radially outward in response to the rotation of the engine jaw and each bears lightly against the inner wall of the starter jaw. This action holds the starter jaw from creeping outwardly towards the rotating engine jaw.