Patent GB-697384-A (GB)
Title: Improvements in and relating to starter motors for internal-combustion engines
Inventor: PULLIN CYRIL GEORGE
IPC: F02N7/10
Filed: 1949-10-07
Abstract: 697,384. Turning-gear; two-stroke engines; driving gear; spray carburetters. HERCULES CYCLE & MOTOR CO., Ltd. Sept. 28, 1950 [Oct. 7, 1949], No. 13117/49. Divided out of 697,313. Classes 7 (ii), 7 (iii) and 7 (v). A starter motor for large internal combustion engines, particularly aero-engines of the piston or turbine type, comprises a two-stroke internal combustion engine with stationary crankshaft and rotary cylinder and crankcase, and a planetary speed reduction gearing of which the sun gear is driven by the crankcase and the annulus gear is free and arrestable by a manually-controlled brake, the planetary cage being connected directly or through further gearing, to the output shaft of the starter motor which is adapted to be connected to the input shaft of a coupling unit connected to the large engine e.g. a claw coupling provided with engaging means and a slippable overload clutch. The starter motor, Fig. 1, comprises a single cylinder two-stroke crankcase engine with rotary cylinder and crankcase 26, 25, and stationary crankshaft 21, which is similar to that fully described in Specification 697,313. The engine is surrounded by a stationary case 36 keyed to the shaft 21 and attached by bolts 53 to a gear case 54 which encloses planetary reduction gearing and is itself attached to a known type of coupling unit 64 fixed to the engine to be started and including a further planetary reduction gearing and a slippable overload clutch transmitting the starter motor drive to a coupling claw 66. A hollow shaft 55 splined to the crankcase 25 carries a sun-gear 56 meshing with planet gears 57 supported in a cage 58 and meshing with an annulus gear 60 freely supported by a bearing 61 on the shaft 55. The outer surface of gear 60 is engagable by brake shoes 62, actuated by a screwed member 63 with an operating handle 94, the starter motor being normally run up to full speed before applying the brake 94 to transmit torque to the coupling 64. The planetary cage 58 is supported on bearings 59 on the crankshaft 21 and is provided with a splined extension 65 in driving connection with the coupling unit 64. The starter motor is provided with a starting handle 47 pivoted at 45 and carrying a toothed sector 44 meshing with a ratchet pinion 45 on the crankcase 25. The control of the brake 94 may be connected to the handle 47 through a lost motion connection necessitating a second pull on handle 47 to operate the annulus brake. The main fuel cock of the starter engine may also be coupled to the handle 47, which handle mechanisin may be replaced by a lanyard and spring- loaded ratchet drum. The rotary motion of the cylinder causes a circulation of cooling air from inlet openings 76 in the case 36. to outlets 77 on its periphery, and the exhaust pipes 91, 92, Fig. 2 extend to near the periphery of the case 36 and are arranged so that the jet reaction of the exhaust assists the rotation of the crankcase. The carburetter 49 with a hand control fuel valve 52a feeds the combustible mixture into the hollow crankshaft 21. In a modification the sun gear 56 is driven from the crankcase through a pair of gears giving a speed reduction and the gear housing 54 houses both the first planetary gear system and a second planetary, reduction gearing coaxial with the first stage and having a fixed annulus gear. The claw-coupling unit 64 in this case does not include a speed reduction gearing.