GB583881A - Engine starter - Google Patents

Abstract

583,881. Turning-gear. BENDIX AVIATION CORPORATION. June 22, 1945, No. 15939. Convention date, June 23, 1944. [Class 7 (v)] An engine starter having a pinion 25 slidable into and out of engagement with an engine gear 29 on acceleration of a starter motor has means to hold the pinion in engagement for starting and to release the pinion on deceleration of the starter motor. The starting circuit includes a battery 1 connected through starter switch 4 to two field windings 6, 7 connected to brushes 9, 11 and through the armature to brushes 12, 13. The armature spindle 16 carries a driving head 18 connected through a tension spring 23 to a slidable screw 22 carrying a nut 30 secured to a barrel 31. The opposite end of the barrel is secured to a clutch member 32 coacting with a clutch member 35 on the pinion, the two members being normally separated by a spring 41 by an amount which is limited by a thimble 38 adapted to provide a frictional drag between the pinion and barrel member. A latch pin 42 is mounted in a ring 43 radially slidable in the nut 30 and is urged into engagement with the screw by a plunger. The screw thread has a notch 51 which when the pinion is engaged coacts with the latch pin to lock pinion in mesh. When the latch is tripped by the operator return of the pinion is facilitated by dynamically braking the starter motor in the manner described in U.S.A. Specification 2,353,900. For this purpose the junctions of the field coils and brushes are connected to 'an electromagnet 55 which when energized closes a switch 56 in parallel with the starter switch. The ends of a resistance 58 in this parallel circuit are connected to a coil 67 adapted to close a switch 61 in a line 62 connected to a coil 64 which projects a finger 65 into the path of latch ring 43. In operation, on closing the switch 4 the screw 22 is rotated and the nut 30 traversed to mesh the pinion. When the latter is arrested by washers 10 the further movement of the barrel closes the clutch 32, 35 to transmit the drive to the pinion. During cranking, the voltage between the brushes 9, 11 and earth actuates coil 55 and closes switch 56. When the engine fires acceleration of the pinion disengages clutch 32, 35 leaving the pinion free to overrun while further backward movement of the barrel and nut is prevented by the latch. If the engine now stalls the shaft 16 overtakes the pinion and cranking is resumed. When the engine becomes self operative switch 4 is opened whereupon the voltage drop across resistance 58 closes switch 61 and causes plunger 65 to disengage the latch and permit return of the pinion. At the same time the earth connection through line 62, 63 short-circuits the armature and produces dynamic braking thereof thereby facilitating pinion disengagement. Switches 56 and 61 then reopen and the finger 65 returns to idle position.