Patent GB-931234-A (GB)
Title: Ignition system
IPC: F02P3/04
Filed: 1961-11-29
Abstract: 931,234. Ignition systems. BENDIX CORPORATION. Nov. 29, 1961 [Dec. 5, 1960], No. 42707/61. Class 7(4). An ignition system for an internalcombustion engine comprises a distributer member driven in timed relation with the operation of the engine so as to establish a sparking circuit to each of the spark gaps of the engine in sequence the sparking circuit including the secondary of a transformer the primary circuit of which includes a direct voltage source and a magnetic member driven in timed relation with the distributer member and co-operating with a stationary magnetic core to provide flux variations inducing electric pulses in an electromagnetic winding associated with the core the pulses being applied to a switching element by a transistor which acts in response to each pulse to establish a current path from the power source through the primary of the transformer and which forms part of a monostable multivibrator circuit which includes a saturable core electromagnetic device by transformer having a winding inserted in the conductive path and a winding connected in a regenerative feed back loop with the switching element so as to apply thereto a feedback pulse acting'to retain the switching element in its active state until the core of the magnetic device becomes saturated. When a signal from the trigger coil 16 appears at the base 46 of transistor 45 by way of transistor 34 current flows from emitter 49 to base 46 and thus causes an amplified emitter-collector current to flow through the primary 52 of the transformer 54 by way of wire 65 primary 61 wire 60 emitter 49 collector 47 and wire 39. The base signal is now removed after having completed its function by the rotation of the finger 15 out of the magnetic field of the core 18. As current flows in the primary 52 of transformer 54 voltage is induced in the secondary 55. Such secondary voltage causes a self excited current to flow in the loop 55, 51, 50, 49, 46, 42 and 57. The impedance of secondary 55 causes the base 46 to be negative with respect to the emitter 49 a base current thus flows in the transistor 45. Such regenerative feedback action continues until the core 58 of the transformer 54 has become saturated. When such condition of saturation of core 58 has been reached the regenerative feedback action ceases so that transistor 45 suddenly becomes non-conductive. The resulting sudden interruption of current flow in the primary 61 of output transformer 62 causes a high voltage to be induced in secondary 64 of the output transformer. Secondary current thus flows to centre contact 21 of the distributer and is fed to the proper sparking plug by distributer arm 22. In a modification three transistors are employed. In Fig. 5 there is fragmentarily shown a further system for facilitating the starting of the engine. The portion of the circuit shown in Fig. 5 is adapted to replace stages 24 and 25 in the circuit of Fig. 2. It is stated that electronic switching elements other than transistors may be employed. The saturable core transformer 58 may be replaced with a saturable core device of the reactor type.