Patent GB-820776-A (GB)
Title: Improvements in or relating to windscreen cleaner systems
IPC: B60S1/48
Filed: 1958-01-02
Abstract: 820,776. Windscreen wipers. GENERAL MOTORS CORPORATION. Jan. 2, 1958 [Jan. 18, 1957], No. 163/58. Class 138(1). A windscreen cleaner system comprises a wiper unit, a washer unit, mechanism for setting both units in operation conjointly, and counter mechanism adapted to continue operation of said washer unit throughout only a first predetermined number of strokes of the wiper unit, and continue operation of the wiper unit for a second predetermined number of strokes after the washer unit has stopped. As shown; in Fig. 1, an electric motor 15 is attached to a pump 17, the intake side of which is connected to reservoir 16 and the outlet side to nozzles 21. The motor drives worm gear 24 to which is attached a cam 25, Fig. 5 contact being maintained between cam and follower 31 carried on plunger 30 by spring 32. This plunger has slots 39 and 63 through the latter of which extends a tang 43 on bracket 40. This bracket 40 is able to reciprocate with the plunger and it allows the spring 50 to expand, and thus to contact bellows 48 of the washer pump. Plunger 30 is also provided with a pawl 42 which can engage the teeth of ratchet wheel 35 on shaft 38. Above the ratchet wheel, Fig. 3, is a cam 37 which controls contacts 82, 84, 86 and below it is a cam 36 which can prevent the reciprocation of plunger 40 by engaging tang 43. So long as electromagnet 57 is de-energized, pawl 42 is prevented by armature 61 from turning ratchet wheel 35. A three position switch has a contact 88, Fig. 6, which controls the operation of the wiper motor only. When in the "Low" position the motor runs at low speed, current flowing from battery 70, through overload switch 71, series field coil 74, motor armature 75, conductors 77, 77a, 79, 88 and 87 to earth. Current also flows from coil 74 through shunt field coil 76, contacts 82 and 84, conductors 85, 89, 88 and 87 to earth. This increases the strength of the field and causes the motor to run slowly. When contact 88 is in the "High" speed position, current is supplied to the motor armature as before but resistance 91 is brought into series with shunt field coil 76, resulting in a weaker field and the motor runs faster. To operate the washer and wiper in combination, assuming contact 88 to be in the "Off" position, button 95 is depressed and the earthing of contact 93 sets the motor into operation. Button 95 also earths contact 94 and energises coil 59 of relay 57 which attracts armature 61 and thus allows, pawl 42 to move round ratchet wheel 35. The movement of the ratchet wheel has two effects. Projection 44 on cam 37 releases contact 84 from 82 and makes it engage 86 thereby keeping the motor running after the button 95 has been released, whilst cam 36 releases tang 43 to allow bracket 40 to reciprocate and thus bring the pump into operation which will continue until tang 43 is prevented from reciprocating by cam 36 after some two thirds of a revolution of ratchet wheel 35. In view of the mechanical linkage between ratchet wheel 35 and the wipers, this two thirds of a revolution is accompanied by a predetermined number of strokes of the wiper and the following third of a revolution during which the pump is inoperative is also accompanied by a predetermined number of strokes. During the rotation of the ratchet wheel 35 the motor runs at high speed because resistor 83 is in series with shunt field winding 76. After wheel 35 has completed one revolution it restores contact 84 to its original position but the motor does not stop until the wipers have reached the parked position when crank arm 80 opens contacts 78.