GB1412711A - Ignition systems for internal combustion engines - Google Patents

Abstract

1412711 Ignition systems ROBERT BOSCH GmbH 30 May 1973 [31 May 1972] 25802/73 Addition to 1027532 Heading F1B An ignition system for a spark ignition internal combustion engine has a first circuit with a primary winding of an ignition transformer and with a storage capacitor 3 for storing electrical energy, a second circuit with an induction winding 1 for storing magnetic energy and control means in each of these two circuits whereby at the instant of ignition the storage capacitor 3 and the induction winding 1 release the energy stored therein to the transformer secondary circuit 9, the control means of the second circuit comprising a contact breaker switch 8 which is operable to control an electronic switch 4 of the control means of the first circuit, the contact breaker switch being connected in parallel with an ignition capacitor 7 when an operating switch 22 is closed a voltage is applied to the input 24, 25 of the voltage converter 20 whereupon a high oscillating voltage is produced in the charging winding 11. This high voltage is converted to a pulsating direct current by the diode 12 and the capacitor 3 is charged. With the contact breaker switch 8 closed the source of direct current 21 supplies current to the winding 1. If the contact breaker switch 8 is opened at the instant of ignition the emitter collector path 32, 34 of the transistor 31 becomes conductive. Thus the control capacitor 36 previously charged by the source of direct current 21 can now discharge by way of the resistor 38, the resistor 33, the emitter collector path 32, 34 and the control resistor 35. A voltage thus appears across the resistor 38 and positively biases the control electrode 37 of the thyristor 5 relative to the cathode 16 to an extent where the switching path 17-16 of the thyristor becomes conductive. Thus the storage capacitor 3 can discharge by way of the switching path 17-16 and the primary winding I of the ignition transformer to produce a spark at the plug 10. At the same time the primary winding circuit is interrupted by the opening of the contact breaker switch 8 whereby a voltage is induced in the secondary winding 9 so that a train of sparks follows the ignition spark produced by the discharge of the condenser. In a modification (not shown) a permanent magnet driven by the engine is associated with the primary winding of the ignition transformer and in a further modification the charging voltage for the capacitor 3 is produced in a charging winding associated with this permanent magnet. Other modifications are described. The secondary winding 9 may be associated with a distributor and a plurality of sparking plugs.