GB1464861A - Road vehicle electrical system including a headlamp wiping and washing control circuit - Google Patents

Abstract

1464861 Windscreen and headlamp cleaning systems LUCAS ELECTRICAL Ltd 8 Feb 1974 [22 March 1973] 13784/73 Heading A4F Vehicle headlamp wipers and washer motors 32, 33 are energized when contacts 13, 15 of a relay switch are inter-connected by a movable contact 12 on energization of the relay coil 11 by the concurrent closure of a switch 27 for engaging the headlamp 28, 29 and a switch 31 for energizing the windscreen washer motor 30. The coil 11 is in series with a transistor 22 which is rendered conducting when the switches 27, 31 are closed by current applied to the base via a variable resistor 24 and diode 23. When switch 31 is reopened, a previously charged capacity 25 discharges to maintain the transistor conducting, providing switch 27 is still closed to keep the headlights on. Thus the headlight wiper and washer motors 32, 33 remain operative for a predetermined period. When the capacitor has discharged, the headlamp wiper motor 32 will still be maintained in operation via contacts 13, 14 and 35, 37 until, at the parking position, contact is broken between 35, 37 and established between 35, 36. Diodes 21, 23 prevent passage of reverse currents.