Patent GB-421468-A (GB)
Title: Improvements in or relating to windscreen wiping apparatus
IPC: B60S1/34
Filed: 1933-04-21
Abstract: 421,468. Windscreen-cleaners. MAY, R. F., 9, Manor Road, Potters Bar, Middlesex. April 21, 1933, No. 11755. [Class 138 (i)] [See also Group XXIV] A slider carrying one or more wiping elements is reciprocated in a horizontal guide tube by means of a reversing gear-box unit comprising gears driven in opposite directions by a continuously-rotating driving element and adapted to be coupled alternately to a driven element which imparts movement to the slider, timing mechanism being geared to the driving element and adapted to permit the driven element to remain coupled to one of the gears during a predetermined number of revolutions of the driven element in one direction or the other and to effect a relatively quick change-over from one gear to the other to produce reversal independently of the mechanism coupling the driven element to the slider. In the construction shown in Figs. 1, 3, 4, 8 and 9, the unit containing the reversal gearing carries a worm spindle 2 adapted to be driven by a flexible drive, the spindle having two worms 2, 2 of opposite pitch engaging respectively with worm wheels on spindles 3a, 4a. The spindle 3a is provided with a gear wheel 3b formed with a toothed sector 3c which is adapted to be engaged by a slidable gear 8 prior to the gear 8 being moved into engagement with the gear 3b. The gear 8 is also adapted to be moved to engage a sector 4<c> and gear 4b on the spindle 4a. When the gear 8 is not driven by either of the spindles 3a, 4a it is locked against rotation by means of a star disc 8b thereon which is engaged by one or other of cams 3d, 4d on the spindles 3a, 4a respectively. The sliding movement of the gear 8 is effected by means of a slidable bifurcated member 12 which is formed with a slot 12a adapted to be engaged by a crank pin 11<a> on a composite gear wheel 11. The wheel meshes with a composite pinion 15 which is adapted to be driven by means of the worm 2<i> on the spindle 2. The gear wheel 11 and pinion 15 consist of three layers, as shown in Fig. 8. In one layer A the pinion 15 is fully toothed and the gear wheel has two toothed segments each having twelve teeth separated by non- toothed segments each occupying the space of eight teeth. In the second layer B the pinion 15 has a single tooth and the gear wheel 11 is fully toothed. In the third layer C the pinion 15 is in the form of a circular disc adapted to co-operate with two oppositely-disposed segments of double-space teeth on the gear wheel 11 to lock the latter against rotation, the disc having a cut-away portion 15a which permits rotation when the single tooth on the pinion 15 in layer B is engaging the gear wheel 11. The result is that the gear wheel 11 is moved in cycles consisting each of three steps of two teeth and one step of fourteen teeth. During the latter step the crank pin 11<a> engages the effective part of the slot 12a on the member 12 thereby moving the sliding gear 8 to effect its reversal. The gear 8 is adapted to engage alternately gears 9e, 9f carried by a spindle 9 which is adapted to drive, through dogs 9c, 10<b>, a spindle 10 carrying a rack pinion 10a. The dogs permit lost motion of the pinion after the rotation of the sliding gear 8 is arrested. The pinion engages a rack 16b on the slider 16, the rack connecting sliding fittings 16c, each carrying a wiper blade 24. Each blade is secured to a member 25<a> adapted to slide between the front wall 19e of a channel member and a spring sealing strip 22 which, as the slider moves along a guide tube 19, prevents the entry of dust. The worm spindle 2 is connected to the flexible drive by dog clutches 2e, 2f and may be disconnected by the manual operation of a spindle 18 provided with a cam 18a adapted to engage a spring lever 17 which is connected to the clutch 2e. In a modification shown in Fig. 10, the driving gears 3<e>, 4e are in constant mesh with gears 27, 26, respectively, which are rotatably mounted on a spindle 9. The spindle is coupled by a dog clutch 9<c> to the driving spindle for the rack pinion which reciprocates the slider. A squared portion 9<g> on the spindle 9 carries a slidable dog clutch 9<h> adapted to co-operate alternately with dogs 26a, 27a on the gears 26, 27. The clutch 9<h> is thrown over by timing gear such as previously described, the sliding member 12 having an arm 12d engaging a groove in the clutch. The mechanism may be driven directly or through a flexible drive, by an electric motor, but is preferably coupled by a flexible drive to the engine or road wheels of the vehicle.