Patent GB-533839-A (GB)
Title: Improvements in or relating to starting apparatus for internal combustion engines
IPC: F02N15/02
Filed: 1939-12-05
Abstract: 533,839. Turning-gear. BOSCH GES., R. Dec. 5, 1939, No. 31471. Convention date, Dec. 5, 1938. [Class 7 (v)] In an engine starter of the type in which the axial movement of a starter pinion 13, connected by a clutch 15 to the starter shaft 16, is effected first by an axial thrust, for example by means of an electromagnet 50, and then by screwthreaded means, the threaded means is prevented by a locking member from operating on the pinion until the pinion is partly in mesh with the teeth of the engine flywheel 35. As shown in Fig. 1, the pinion 13 and the pressure member 14 of the disc clutch 15 are mounted on screw threads 11, 12 on a rotatable sleeve 10, and the driving member 18 of the clutch 15 is secured upon the shaft 16 of the starting motor 17. Axial movement of the sleeve 10 and pinion 13 to initiate meshing of the pinion is effected by a thrust rod 24 actuated through a lever 52 by the electromagnet 50, which also closes the circuit of the starting motor by means of a switch 56 when the pinion is partly in mesh with the flywheel 35. The rod 24 engages the sleeve 10 by means of a shoulder 25 on the rod in engagement with a ball 26 in an opening in the sleeve ; when the pinion comes into mesh, the ball 26 rides over the shoulder 25 into a groove 34 in the shaft 16. Shoulders 27, 29 on the rod initially hold balls 28, 30 in engagement with recesses in the pressure member 14 and the pinion 13 and thus prevent tightening of the clutch and movement of the pinion relatively to the sleeve 10. When the pinion is partly in mesh and the ball 26 enters the groove 34, further axial movement of the rod 24 releases the balls 28, 30 from the shoulders 27, 29, and rotation of the motor causes the tightening of the clutch 15 by the pressure member and movement of the pinion 13 on the thread 11 into full driving engagement with the flywheel. If the teeth of the pinion clash with the flywheel, the locking balls 28, 30 prevent further actuation of the clutch and pinion until the pinion is turned into meshing position. In a modification, Fig. 4, the shaft 78 of the pinion 79 is slidably keyed in the sleeve 72 on which the pressure member 70 of the clutch is threaded. Locking balls 76, 77 are arranged in openings in the sleeve 72. Initially the ball 76 is held by the shaft 78 in engagement with a triangular groove 71 in the pressure member 70, and the ball 77 is engaged by the forward edge of a slidable ring 83 actuated by a spring 84. When the thrust rod 81 is moved axially by an electromagnet, the pinion is moved into partial mesh with the engine flywheel by the engagement of a shoulder 82 on the rod with the coned end 80 of the shaft 78, and the ball 76 is released. The pinion is advanced into full mesh by the threaded connection between the pressure member 70 and the sleeve 72, and the ball 77 is forced into the groove 71 by the spring-loaded ring 83, preventing premature disengagement of the pinion. When the starting motor is switched off, the collar 82 displaces the ring 83 and releases the ball 77 from the groove 71 to allow the movement of the pinion out of mesh. In a further modification, the pinion is mounted externally on the threaded sleeve and is provided with a pin projecting radially' through a slot in the sleeve into engagement with the thrust rod.