Patent GB-714406-A (GB)
Title: Improvements in electric starting apparatus for internal combustion engines
IPC: F02N15/06
Filed: 1952-12-15
Abstract: 714,406. Turning-gear. GENERAL MOTORS CORPORATION. Dec. 15, 1952 [Dec. 15, 1951], No. 31661/52. Class 7(5) In electric engine-starting apparatus comprising a hollow shaft 30, Fig. 1, on which the starter pinion 26 is axially slidable into mesh with the engine, latch means, such as members 120, 122, Fig. 6, mounted in the shaft 30 and movable radially outwards to maintain the pinion in mesh with the engine, there is provided a latch-operating member, for example shaft 140, Fig. 1, which extends within shaft 30 and is so responsive to the starter-motor switch 90 that the members 120, 122 become operative when the switch is closed and the pinion in mesh, and become inoperative only when the switch 90 is opened. Pinion drive. The hollow motor-shaft 30 has a sleeve 36 fixed thereto which is in threaded engagement with an outer sleeve 46 whilst a spring 50 is secured to each of the sleeves to normally hold the sleeve 46 and assist its return to the inoperative position shown; a member 52 on sleeve 46 engages sleeve 36 when the parts are in the positions shown. The pinion 26 is integral with a tube 54 that is surrounded by a flanged sleeve 58 which abuts tube 54; one end of flanged sleeve 58 is spigotted to sleeve 46 and its other end engages splines 62 that are integral with a ring 64, the splines extending into spaces between the pinion teeth. A spring 72 between the pinion and flanged sleeve 58 maintains the pinion 26 and sleeve 58 in the inoperative positions shown. Torque is transmitted between sleeves 46 and 58 by a spring 80 retained in position by a cover 84; the spring grips the outer sleeve surfaces and acts as a clutch as well as cushioning the shock of torque transmission. In the event of tooth abutment the sleeves 46 and 58 continue their leftward movement and compress spring 72 so that the torque through spring 80 rotates the pinion which indexes correctly and is then forced into full mesh by expansion of spring 72. When the engine starts the spring clutch 80 slips to permit the pinion to rotate faster than shaft 30 and sleeve 36. In a modification the shock of torque transmission is cushioned by permitting sleeve 36 a slight movement relative to shaft 30 and providing a pair of spring washers, separated by a pre-loading disc with spring fingers formed therein, between the end of sleeve 36 and a shoulder on shaft 30; the spring fingers may be adjusted to vary the degree of pre-loading. The electromagnetic starter switch may be replaced by a manual switch. Latch mechanism. The two members 120, 122, Figs. 5 and 6 are received in openings on opposite sides of shaft 30, and are located in a slot 126 in a member 128 integral with the head 130 of a rod 132, the head being slidable within shaft 30; a pin 134 in member 128 seats in slots 136 and 138 in members 120 and 122. The rod 132 is connected to the shaft 140, Fig. 1, which abuts the end of the switch plunger 108 so that upon energizing the switch solenoid 110 the plunger is moved rightwardly and upon the pinion meshing with the engine gear a compressed spring 154 urges shaft 140 rightwardly to engage the latches with the end of tube 54; the shaft 140 is moved leftwardly to retract the latches upon de-energization of solenoid 110 since switch plunger-spring 116 is stronger than spring 154. In a modification, the latches are designed to assume their operative positions under the -centrifugal force exerted by the motor during engine cranking whilst withdrawal of the latches is effected as previously described.