GB1487265A - System for the intermittent operation of a wiper motor for vehicles - Google Patents

Abstract

1487265 Control of D.C. motors SWFSPEZIALFABRIK FUER AUTOZUBEHOER GUSTAV RAU GmbH 24 Jan 1975 [2 March 1974] 3304/75 Heading H2J The wiper motor M of a vehicle is energized from a D.C. supply 15, 31 and controlled by a parking switch RS, a wiper switch WS, an intermittent operation switch S and an intermittent dwell control device KS, movement of the switch WS to position I or II causing the motor to run continuously at a low or high speed respectively, movement of switch WS to position 0 with switch S open completing a short-circuit braking circuit across the motor via terminals 53, 87, relay contact a, wiper switch WS, terminal 31b and the closed centre and left outer contacts of switch RS, and closure of switch S with switch WS in position 0 producing a succession of single wiping cycles for as long as switch S is closed, each wiping cycle consisting of the following sequence of operations: (1) Capacitor C is charged from terminal 15 through switch S, variable resistor P, switch WS and the closed centre and left outer contacts of switch RS to terminal 31. (2) Transistor T2 conducts to turn on transistor T1 and so energize relay A ,whose contact a changes over to break the short-circuit across the motor and connects its low speed winding (terminals 53, 53a) across terminals 15, 31. (3) The resultant motor movement changes over the centre contact of switch RS to engage the right outer contact and so connect capacitor C to the terminal 15 through the switch WS, the capacitor voltage changing to the volt drop across resistor P. (4) When the wiping cycle is completed, the switch RS returns to its original state to connect capacitor C through switch WS across the base-emitter junction of transistor T2, which turns off to switch off transistor T, de-energize relay A and change over contact a. (5) Contact a re-establishes the motor braking circuit to stop the motor and capacitor C first discharges through switch WS, switch RS, terminals 31, 15, switch S and resistor P and then recharges through this same circuit to commence another wiping cycle, the delay between cycles being variable by adjustment of resistor P.