GB1002586A - Improvements in ignition systems for internal combustion engines - Google Patents

Abstract

1,002,586. Spark ignition systems. ROBERT BOSCH G.m.b.H. May 11, 1962 [May 13, 1961], No. 18119/62. Heading F1B. [Also in Division H2] In an ignition system comprising a normally conducting transistor 13 which is energized to block the current flow through the primary 10 of an ignition coil 11 at the instant of ignition, the base of the transistor is connected to the tapping of a voltage divider 25, 26, connected across the D.C. source, through a resistor 27 in parallel with which is connected an enginedriven permanent magnet impulse generator 30 and a rectifier 34, the magnetic system of the generator being such that the impulse induced in the generator winding and passing through the rectifier to block the transistor has a duration, at most, of a quarter of the periodic time of the pulses. The pulse generator is. built-into the distributer 40, Fig. 2, and comprises an axially polarised rotary magnet 54 and stationary windings 31, 32, each of which has a rectifier 34, 35, Fig. 1, associated therewith. In Fig. 2 the magnet has an upper polepiece 55 with two narrow axial ribs 58, 59, and lower polepiece 60 with similar narrow ribs 63, 64, Fig. 3. The windings 31, 32 are surrounded by sheet metal casings 65, 66, having interfitting polepieces 72, 73, and 68, 69, with small air gaps between adjacent polepieces. The magnet 54 generates sharp positive and negative pulses in the windings each time its polepieces pass the air gaps between the stator polepieces. Due to the rectifiers 34, 35, only the positive pulses are operative to block the transistor 13, whereby a high voltage is induced in the secondary coil 12 connected through the distributer 18 to the spark plugs 22. In a modification, Fig. 7, the impulse generator magnet comprises circumferentially polarised magnets 82 with soft iron polepieces 81 held within a synthetic resin casing 83, 84. In Fig. 9 the magnet is formed with four arms 91 on which laminated polepieces 94 are riveted.