Patent GB-748759-A (GB)
Title: Improvements in or relating to windscreen wiper blades
IPC: B60S1/38
Filed: 1952-02-20
Abstract: 748,759. Windscreen cleaners. O'SHEI, W. E. Feb. 20, 1953 [Feb. 20, 1952; March 15, 1952], Nos. 4496/52 and 6772/52. Class 138(1) A windscreen wiper blade comprises a squeegee mounted in a plurality of pivotably or otherwise flexibly interconnected backing members extending therealong so that, when the squeegee wipes a portion of the windscreen which is flat or has minimum curvature, the wiper arm pressure will be positively applied at all points or at closely spaced points along the squeegee, and when the squeegee wipes a portion of the windscreen of more convex curvature, the arm pressure will be applied to the squeegee intermediate the ends of the backing members, all or some portions of the squeegee, where the pressure is not so applied, moving outwardly of the adjacent portions of the backing members to conform with the curvature of the windscreen. In the embodiment of Figs. 2 and 3 the squeegee 1 is provided with rear flanges 2 and side ribs 3 to form opposed side grooves 4. Spaced along the back of the squeegee and enclosing the flanges 2 are four rigid channel shaped backing members 6 the free edges of the side walls 7 of which are straight and provided with inturned flanges 8 disposed in the grooves 4. The outer members have downturned portions 5 to retain the squeegee. Transverse flexing of the squeegee is prevented by the side walls 7 but their spacing permits of up and down movement of the squeegee in the members 6 controlled by the width of the grooves 4. The backing members 6 each have apertures 19<SP>1</SP> to pivotally receive the ends 18<SP>1</SP> of channelled secondary yokes 21 which in turn have apertures 19 to pivotally receive the ends 18 of a channelled bridge piece 10 connectable with the wiper arm 14. The connections between the bridge piece, yokes and backing members are such that they can only be separated when the parts are at right angles to one another. When wiping a portion of the windscreen which is flat or of minimum curvature the arm pressure applied at the ends 19<SP>1</SP> of the yokes will be transmitted to the flanges 8 and the rear surfaces of the ribs 3 along the entire length of the squeegee. When wiping over a portion of the screen of greater convex curvature the yokes will pivot and assume positions which are parallel to tangents to the surface of the screen and the pressure through the yoke ends 19<SP>1</SP> will be transmitted to the adjacent central parts of the flanges 8 and thus to the ribs. Between the pressure points 19<SP>1</SP> and at the extreme ends of the squeegee, the ribs 3 will move outwardly from the flanges 8, the flanges 2 still being out of contact with the upper surfaces of the flanges 8, so that the squeegee conforms to the windscreen surface. Outward movement of the ends of the squeegee is assisted by leaf springs 15 secured to the backs 9 of the outer members 6. Such springs may be provided at each end of each member 6, or the springs may be constituted by resilient portions formed integrally with the back of the squeegee and adapted to engage the backs of the channel members 6. Freely floating channel members may be provided between adjacent spaced ends of the members 6 and these may have end extension fingers entering into the channels of the members 6, so as to restrain transverse flexing of the squeegee at these points. Furthermore the central regions of the free edges of the side walls 7 may be flangeless. In another embodiment only two backing members are provided and pivoted by transverse pins directly to the ends of the bridge piece. The inturned flanges of the side walls and the outer end walls are all formed integrally, the backing 'members being moulded from a synthetic resin plastic. In a further embodiment Fig. 5, having two backing members 6<SP>11</SP>, the bridge piece 10" and particularly its projecting ends 23, is flexible. These ends are connected to perpendicular pivots 24 which also serve to anchor bowed flat section springs 25 within the channels of the members 6<SP>11</SP>. Instead of using springs to urge those portions of the squeegee, to which arm pressure is not positively applied, away from the backs of the backing members, the connections of the bridge piece or secondary yokes to the outer backing members may be off-centre and nearer to the ends of the squeegee. Alternatively in the case of more than two backing members the outer members may be shorter than the remainder. Furthermore the outer ends of the wiping edge of the squeegee may be deeper than the remainder of the edge. These deeper ends can fold over as the wiper is actuated. Rocking of the squeegee within the channels of the backing members is permitted to allow the blade to assume an inclined trailing position as it moves over the screen. Specifications 433,467, 666,473 666,474, 666,478, [Group XXII], 675,757, 679,540, 683,201 and 712,610 are referred to. Reference has been directed by the Comptroller to Specifications 710,360 and 712,610.