GB1498240A - Ignition systems - Google Patents

Abstract

1498240 Ignition systems ROBERT BOSCH GmbH 31 Oct 1975 [2 Nov 1974] 45137/75 Heading F1B An ignition system for an internal combustion engine has an ignition coil 5 the primary winding of which is divided into first and second component windings 6, 7 the first component winding 6 being connected in series with two parallel connected circuit branches, the first of which branches includes a first switch 12 and the second of which branches includes a series combination comprising the second component winding 7 and a second switch 13. For the purpose of preparing for the ignition operation the first switch 12 is arranged to be in its conductive state in the first instance and assume its non-conductive state when the first component winding 6 carries sufficient current for adequate ignition energy, while the second switch 3 is arranged to be in its conductive state and as the instant of ignition is approached the first switch is again arranged to assume its conductive state and the second switch to assume its non- conductive state, so that, with regard to the primary winding of the ignition coil, only the flow of current in the first component winding 6 has to be interrupted by the first switch 12 at the instant of ignition, while the second component winding 9 has already been de-energized by the non- conductive state of the second switch. An electrical storage member (capacitor 40), is used for changing over the first switch 12 (transistors 14) into its non-conductive state when sufficient current for adequate ignition energy is present in the first component winding. A threshold valve switch 46, which for example operates in the manner of a Schmitt trigger, is provided and the output 47 of the switch 46 is used to control the transistors 49 and 14. As shown a mechanically operated circuit breaker 29 is used to control the ignition system. An optical signal generator or an alternating current signal generator may be used in place of the contact breakers.