GB1333085A - Windscreen cleaning apparatus - Google Patents

Abstract

1333085 Windscreen cleaners R H EVANS 14 Jan 1971 [7 Feb 1970] 5991/70 Heading A4F [Also in Divisions F1 H3] A windscreen cleaning apparatus incorporates means for controlling the intervals between successive sweeps of a windscreen wiper and means for delivering individual doses of washing liquid from a windscreen washer in synchronism with the movement of the wiper. With the main switch SW, Fig. 2, in the position shown, and the washer control switch WS closed, energization of a control unit 9 by closure of a switch 10, Fig.3, produces timed pulses each operating a relay RL/2 to interconnect conduits h, i of a switch IS whereby the wiper motor (not shown) in unit 30 operates the wiper for one complete sweep under the control of a parking switch PS Fig. 1, (not shown), and simultaneously a pump 6 is energized to deliver a dose of washing liquid to spray nozzles 8. When the main switch SW is actuated to interconnect contacts 3, 4 the wiper motor operates continuously. The control unit 9 comprises a capacitor C, which is charged via resistors R 1 , R 2 on closure of the switch 10, to render a transistor TR 1 conducting. The relay RL/2 is thus energized to change over the contacts of the switch RL, so that the capacitor Cl discharges through resistor R 4 . The transistor TR, is then rendered non-conducting and the switch RL, reconnects the point b to earth, so that the potential at points a and A drops to a negative value almost equal to the battery voltage, thus ensuring a substantial time interval for re-charging the capacitor C 1 between pulses.