GB2112276A

GB2112276A - Windscreen wiper blade for motor vehicles

Info

Publication number: GB2112276A
Application number: GB08233769A
Authority: GB
Inventors: Alfred Kohler; Hans Prohaska
Original assignee: SWF Spezialfabrik fuer Autozubehoer Gustav Rau GmbH
Current assignee: SWF Auto Electric GmbH
Priority date: 1981-12-28
Filing date: 1982-11-26
Publication date: 1983-07-20
Also published as: FR2518944A1; ES269182Y; DE3151644A1; ES269182U

Abstract

A windscreen wiper blade for motor vehicles comprises a main yoke of substantially U-shaped cross- section having two side walls 11 and a back 12 with an aperture spanned by a planar web 14. The main yoke is formed in one piece from a sheet metal billet. A coupling member 20 may be connected to the web 14 for the purpose of coupling the wiper blade to wiper arm 30. The member may have a chamber 26 provided with tips 26a on which web 14 may pivot in use. <IMAGE>

Description

SPECIFICATION Windscreen wiper for motor vehicles This invention relates to a windscreen wiper for motor vehicles.

German patent specification No. 2 447 640 discloses a windscreen wiper in which flat strips are cut from the back of the wiper arm main yoke and formed to a roller. This roller takes over the function of the rivet-headed pin used in this place in earlier forms of wiper and represents the articulating joint for the wiper arm. Special tools and a great amount of production technique are necessary to produce such a main yoke, giving rise to the significant risk of crackings and material distortions occurring on the main yoke, especially laterally of the moving joint.

From the German laid open specification 2 711109 is known a windscreen wiper in which an articulating joint for the wiper arm, is also formed out of the back of the wiper blade main yoke, the production technique of which seems to be controllable more easily. Presumably also in this version material distortions can, however, not be excluded, because the moving joint is also subjected to great deformation forces in order to obtain the required shape. Moreover, by arranging the moving joint on one of the transverse rims of the main yoke aperture the space to be bridged in the longitudinal direction of the wiper blade is so large, so that there is an increased risk that the wiper blade will accidentally slide off the wiper arm and be lost.

It is an object of the present invention to create a windscreen wiper whose wiper blade can be provided with an articulating joint simply and economically.

According to the present invention there is provided a windscreen wiper blade for motor vehicles, which blade includes a main yoke formed in one piece from a sheet metal billet, which yoke is substantially U-shaped in cross-section and has two side walls connected by an apertured back that includes a planar transverse web for engaging a co-operating wiper arm via a coupling member.

The sheet metal billet of the wiper blade main yoke according to the invention can be produced and shaped with much simpler tools than that of the prior art. In this case there is minimal risk of crackings or material distortions on the main yoke because the joint is not produced in a separate shaping-action. The bearing surfaces, round which a swivelling motion can be carried out, in this case are formed by the coupling member just as the guiding surfaces for the wiper arm.

A lateral guidance with only a little play is especially possible, when the moving joint is positioned slightly below the plane of the wiper blade main yoke back. In this case the coupling member can better be held in an indisplaceable position by the side walls of the wiper blade. In the windscreen wiper according to the invention, various planes are obtained in a simple way during the bending operation, when the area of the sheet metal billet forming the web is held for bending at right angles to the areas forming the side walls, while the area of the sheet metal billet forming the back is not pressure-loaded, so that it is slightly curved upwards after the bending operation.

The coupling member can thereby be held in fixed (non-pivoting) relationship either with the wiper arm or with the wiper blade. In the first case the wiper arm volume is increased by the coupling member, in the second case the web volume, so that in both cases reliable coupling and guidance is ensured.

Especially preferred is a structure which is based on the mode of operation of a fulcrum bearing. By a fulcrum bearing is understood a support of a girder in the way of a point or a knife edge fulcrum which permits an unhindered rotation of the girder on the bearing at least through a limited arc. With regard to the present invention the web of the wiper blade functions as the girder.

A reliable fit of the coupling member is especially ensured when it may be resiliently deformed and laps over the web almost entirely.

As a material for the coupling member in particular, a resilient plastics material can be used.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a top view on the central area of the wiper blade of a windscreen wiper according to the invention, Fig. 2 is a longitudinal section through that part of the windscreen wiper blade of Fig. 1, which in this case is engaged with a coupling member secured to the wiper arm, Figs. 3 and 4 are different views on this coupling member, Fig. 5 is a longitudinal section through that part of the windscreen wiper which has been shown in Fig. 1 , which in this case is equipped with a coupling member secured to the web, and Fig. 6 is a top view on the windscreen wiper shown in Fig. 5.

The windscreen wiper according to the invention comprises a wiper blade, of which the central area of its main yoke 10 is shown in Figs 1, 2, 5 and 6. The main yoke 10 has a substantially U-shaped cross-section with two side walls 11 and a back 12 connecting the side walls 1 As especially Fig. 1 shows, this area has been cut open in an area 13 towards the wiper blade axis of symmetry and parts of the back have been removed in a way to leave a web 14 approximately in the centre. The section through the back has been made in such a way that in a partial area of the aperture 13 two lugs 15 are formed which, as Figs. 2 and 5 show, are bent upwards in such a way that they enlarge the height of the side walls 11 and form guiding walls for a coupling member 20 or 40.The coupling member 20 or 40 is arranged between the side walls 1 1 of the wiper blade 10 and effects the connection between the wiper blade 10 and a wiper arm 30 or 50 having a hook-shaped bent end 31 or 51. In Figs. 2 and 5 all rear side walls are shown in non-sectional view, the sectional planes of the main yoke back 12, coupling member 20 or 40 and wiper arm 30 or 50 are hatched. The web 14 of the main yoke 10 has a rectangular cross-section, its width b (Fig. 1) corresponds to about one third of the height of the side walls 11 (Figs. 2 and 5). The web is positioned slightly below the plane of the main yoke back 12, so that the coupling member 20 or 40, which in a sectional view is approximately U-shaped, can be held in a position free from play relative to the side walls 11 of the main yoke with the assistance of the lugs 15.

The coupling member 20 of Fig. 2 is made from a resilient material, preferably from a plastics material, and has a body 21 which is equipped with two legs 22, 23 arranged parallel with each other. The coupling member 20 is designed in a way that the body 21 is exactly fitting the inner surface 31 a of the wiper arm hook 31, when it is inserted and the outer surfaces of the legs 22, 23 rest closely against the opposite inner surfaces of the members 32, 33 of the wiper arm 31. The body 21 has an opening 24 receiving the web 14, which opening starts from one outer rim of the coupling member 20 as a slot 25 extending obliquely to the centre of the body 21, whose width is slightly greater than the height of the web 14 by an amount providing clearance.The slot 25 opens into a central chamber 26 that is substantially cylindrical with a diameter that is slightly larger than the width of the web 14 in order to provide clearance. Triangular section ribs extend inwardly from the upper and lower quadrants of this cylinder. The tips 26a of these ribs form co-operating surfaces in the form of knife edges on which the web 14 is supported. The tips 26a thus represent a knife edge fulcrum bearing for the web 14 allowing it to pivot so that when the wiper blade is operated its orientation can adjust itself to follow the differing curvatures of a pane to be cleaned.

The coupling member is mounted on the web 14 of the main yoke 10 by first holding the coupling member 20 between the side walls 11 of the main yoke 10 in a way that the slot 25 of the coupling member 20 is aligned with the plane of the web 1 4 in the direction of the wiper blade axis of symmetry. Thereafter the coupling member 20 with its slot 25 is pushed over the web until the pushing motion is limited by the end of the central area 26. If now the coupling member 20 is released the coupling member 20 pivots round the web 14 and occupy a position corresponding to its centre of gravity.

In order to couple the wiper arm 30 with the main yoke of the wiper blade the coupling member 20 is brought into a position in which its legs 22, 23 are approximately parallel to the back 12 of the main yoke and inserts the main yoke equipped with the coupling member 20 is inserted into the inside of the wiper arm hook 31. As Fig. 2 shows that the lower member 33 of the wiper arm hook 31 has a recess 34 in which the coupling member engages with a detent 27. Figs. 3 and 4 show the detent 27 is formed on a tongue 28 which is formed out of the lower leg 23 of the coupling member 20. This tongue 28 is resilient and, in the unloaded condition, occupies a position which lies at an angle beneath the plane of the leg 23.If now, as described above, the wiper blade is inserted in the wiper arm hook 31 the tongue 28 is deflected upwards due to the pressure exerted by the wiper hook member 33 until the detent 27 is positioned above the opening 34. Because the detent 27 has smaller dimensions than the opening 34 the detent 27 engages in the opening 34 until the tongue 28 rests against the wiper hook member 33. As can be seen from Fig. 2 the upper wiper hook member 32 of the wiper arm hook 31 covers the slot 25, so that the wiper blade is captively held on the wiper arm 30. The elongation 28a provided on the tongue 28 facilitates a loosening of the locking connection when the wiper blade has to be exchanged.

Figs. 2 and 3 in particular also show the coupling member 20 has two side walls 29 extending beyond the legs 22, 23 and beyond the body 21, which side walls guide the wiper arm hook 31 laterally, so that by the arrangement according to the invention a reliable coupling has been created, which can easily be realised.

The coupling member 40 shown in Figs. 5 and 6 is made from a relatively soft resilient material, preferably a plastics material. It comprises a solid body 41 which is inserted in the hook-shaped end 51 of a wiper arm 50. The body 41 is provided with an opening 44, which extends approximately in parallel to the axis of curvature of the body 41 and starts from one outer rim of the coupling member 40 as a slot 45 extending straight towards the centre of the body 41, the width of this slot being slightly larger than the thickness of the web 14 to provide clearance. The slot 45 ends in a central area 46, which in the unmounted, and therefore unstressed condition, has a circular cross-section whose diameter is smaller than the width (b) of the web 14.During the mounting operation of the coupling member 40 on the main yoke 10, which is carried out in a manner similar to that of the coupling member 20, the central area 46 is widened to an oval shape due to the larger width of the web 14, so that the coupling member is held in fixed relationship with respect to the web 14.

Fig. 5 shows that the body 41 of the coupling member 40 rests with its curved surface 41 a closely against the curved inner surface 51 a of the wiper arm hook 51. One side of the body 41 is tapered so that its upper surface 42 includes with the inner surface 52a of the upper wiper hook member 52 an angle a of about ten degrees. The lower surface of the body 41 includes a similar angle with the inner surface 53a of the lower wiper hook member 53. These angles diverse to the side of the body 41 not facing the curvature summit, so that the surfaces 41 a, 42 and 43 of the coupling member 40 form joint surfaces, around which the wiper arm 50 can be swivelled.

The wiper arm 50 is secured by the ends 48a of two tongues 48, which are angled inwardly from the side walls 49 of the coupling member 40. The shape of the ends 48a is adapted to the outer curvature 51 b of the wiper arm hook 51, so that the wiper arm 50 is captively connected with the coupling member 40. Because the recess 44 of the coupling member 40 is covered by the wiper hook members 52 of the wiper arm 50, the coupling member 40 cannot slide off the wiper blade accidentally, so that also by this arrangement a reliable coupling is created which can easily be effected.

Although both embodiments show a wiper arm with a hook-shaped end the invention is not restricted to the use of wiper arms of this kind. A use of a wiper arm with a straight-lined end would also be possible which, for example, could extend laterally to the wiper blade axis of symmetry as well. Essential with regard to the present invention is the basic idea of avoiding all complicated form work on the moving joint arranged on the wiper blade and to arrange the necessary joint and guiding surfaces on a coupling member which can be produced in a simple way, for example by injection-moulding.

Claims

1. A windscreen wiper blade for motor vehicles, which blade includes a main yoke formed in one piece from a sheet metal billet, which yoke is substantially U-shaped in cross-section and has two side walls connected by an apertured back that includes a planar transverse web for engaging a co-operating wiper arm via a coupling member.

2. A wiper blade as claimed in claim 1 , wherein the plane of the web is positioned below the plane of the main yoke back.

3. A wiper blade substantially as hereinbefore described with reference to Figs.1,2,5 and 6 of the accompanying drawings.

4. The combination consisting of a wiper blade as claimed in claim 1,2 or 3, and a co-operating coupling member for coupling the blade to a cooperating windscreen wiper arm.

5. The combination as claimed in claim 4, wherein the coupling member is resiliently deformable.

6. The combination as claimed in claim 3 or 4, wherein the coupling member is provided with an opening in its outer surface which starts from that surface in the form of a slot whose width at all points is larger than the thickness of the web by an amount providing clearance, which slot opens into a central chamber which receives the web in its operating position.

7. The combination as claimed in claim 6, wherein the coupler forms a pivotal mount for the web and is itself adapted to be held in fixed relationship with the wiper arm.

8. The combination as claimed in claim 6, wherein the web is held in fixed relationship with respect to the coupling member and the outer surface of the coupling member forms a bearing surface adapted to enable the coupling member to pivot about the wiper arm.

9. The combination as claimed in claim 7, wherein in the direction of the wiper blade axis of symmetry the coupling member chamber is wider than the width of the web by an amount providing clearance, and is provided with inwardly directed projections which touch the two major surfaces of the web and co-operate to form a pivot for the web.

10. The combination as claimed in claim 9, wherein the projections have the form of knife edge pivots.

11. The combination as claimed in claim 7, 9 or 10, wherein the coupling member has a catch for engagement in a co-operating recess formed in the wiper arm.

12. The combination as claimed in claim 7, 9, 10 or 11, wherein the coupling member has a body with two resilient legs the outer surfaces of which are adapted to be urged against the inner surface of a hook formed on the co-operating wiper arm.

13. The combination as claimed in claim 8, wherein the unstressed width of the chamber is less than that of the web, and in the operating position is widened in the direction of the wiper blade axis of symmetry by the web such that it is braced across the chamber.

14. The combination as claimed in claim 8 or 13, wherein the coupling member outer surfaces are provided on one side of the chamber by two planes converging at an actue angle with increasing distance from the chamber.

15. The combination as claimed in claim 14, wherein the coupling member is provided on the other side of the chamber with locking means adapted to engage the outer surface of the curved portion of the hook of a hooked wiper arm engaged with the combination.

16. The combination as claimed in claim 6 or any subsequent claim appended thereto, wherein the shape of the coupling member is such that its slot is covered by a co-operating hooked wiper arm engaged therewith.

17. The combination of wiper blade and cooperating coupling member substantially as hereinbefore described with reference to Fig. 1 and Figs. 2, 3 and 4, or to Fig. 1 and Figs. 5 and 6 of the accompanying drawings.

18. The combination of wiper blade, wiper arm and coupling member substantially as hereinbefore described with reference to Fig. 1 and Figs. 2, 3 and 4, orto Fig. 1 and Figs. 5 and 6 of the accompanying drawings.