SE7413159L

1488041 Vehicle headlamp and windscreen cleaning systems BAYERISCHE MOTOREN WERKE AG 18 Oct 1974 [19 Oct 1973] 45233/74 Heading A4F In a motor vehicle headlamp and windscreen cleaning system, the switching control is such that (a) the lamp cleaning equipment will operate at the instant when the lamp or lamps are switched on only when the windscreen cleaning equipment has been previously operated since the lamp cleaning equipment was last operated, and/or (b) the lamp cleaning equipment will operate at the instant when the windscreen cleaning equipment is operated, at a time when the lamps are already on, provided that a predetermined interval has elapsed since the last operation of the lamp cleaning equipment. The lamp cleaning equipment comprising wiper and washer motors 21, 22 and 28 is energized in the first manner (a) by closure of the ignition switch 15 and closure of a switch 1 to apply a negative voltage to a terminal 7 of an electronic control unit 8 to charge a capacitor (C 1 ) Fig. 2, (not shown) via a resistor (R 1 ) and to maintain a transistor (T 1 ) non-conducting. On release of the switch 1 the transistor (T 1 ) and a further transistor (T 2 ) conduct to operate a relay 16 to engage contacts 18, 18' to energize the wiper and washer motors 21, 22, 28 for a period determined by the time of discharge of the capacitor (C 1 ) via resistors (R 2 , R 3 ). Alternatively the lamp cleaning equipment is energized in the second manner (b) after closing switch 15, by closure of a switch 13 to switch on the headlamps 11, 12 to apply a positive voltage to a contact 10. This voltage will render the transistors (T 1 , T 2 ) conducting to energize the wiper and washer motors only if a silicon controlled rectifier (Ty) has been rendered conducting by the application of a negative voltage to the terminal 7 by previous operation of the switch 1 to energize windscreen cleaning equipment 30. De-energization of the relay 16 renders a further transistor (T3) conducting for a period determined by the time of discharge of a further capacitor (C 2 ), during which period the relay 16 cannot be energized by operation of the switch 1 again.