GB1380483A - Automatic cranking systems for motor vehicle internal combustion engines - Google Patents

Abstract

1380483 Starting prime movers GENERAL MOTORS CORP 17 Aug 1972 [1 Sept 1971 (2)] 38406/72 Heading H2H A system for automatically cranking the engine of a motor vehicle comprises a starter motor, an engine speed tachometer and a vehicle speed tachometer, the system being so arranged that, independently of the normal starter motor circuit, the starter motor is energized when the engine speed is below a predetermined minimum speed and the vehicle speed is above a predetermined speed. The wheel speed of a vehicle is sensed by a rotating magnet 32 operating a reed switch 26 so as to produce voltage pulses which charge a capacitor 42 such that at a predetermined vehicle speed the charge on the capacitor 42 is sufficient to cause a bi-stable pair of switching transistors 46, 52 to assume a state in which the output voltage at the collector of transistor 52 is high, this voltage being applied to the base of a transistor 106 in a gate circuit 22. The speed of the engine of the vehicle is sensed by applying the pulses which occur at the primary winding 58 of the vehicle ignition coil 59 when the contact breaker 60 opens to a capacitor 90 by way of a transistor 66 so that the capacitor 90 receives a charge depending on the speed of the engine. When the capacitor 90 is charged sufficiently it causes a bi-stable pair of switching transistors 94, 100 to assume a state wherein the output voltage at the collector of the transistor 100 is high, this voltage being applied to the base of a second transistor 108 in the gate circuit 22. When both transistors 106, 108 are non-conductive a transistor 112 is conductive to energize a relay 114 which closes a contact 116 to energize the starter solenoid 118 so as to crank the engine; the transistors 106, 108 only being in their non-conductive states when the output from transistor 52 is high and the output from transistor 100 is low respectively. Thus the starter solenoid can only be energized when the vehicle speed is above a given speed and the engine speed is substantially zero. Normal engine starting is effected by closing the PARK and NEUTRAL safety switch 121 and the starting switch 122. In a second embodiment the voltage signals obtained by the vehicle and engine speed sensors are of opposite polarities, the sum of the signals being used to control the gate 22.