FIELD OF THE INVENTION This invention relates to a backing for windscreen wiper blades and relates particularly, but not exclusively, to such for motor vehicles.

DESCRIPTION OF PRIOR ART

Hitherto it has been common in the motor vehicle arts to provide for windscreen wiper blade inserts to be held by a backing and wherein the backing is, in turn, held by a blade frame. The blade frame locates about a pair of flanges which extend along the side edges of the backing. There are two distinct widths of the blade frames which have been adopted. A first width is 6mm and the other width is 8mm.

As the blade inserts are identical in size regardless of whether they are for the 6mm wide or 8mm wide blade frame, it has been necessary to provide the backings themselves of appropriate width to suit the two sizes of the blade frames which have been adopted. This, in turn, requires for unnecessary stock to be handled and processed by the manufacturers, suppliers and/or retail outlets. The above problem has been recognised in Australian Patent Application No. 78133/75 to Trico

Products Corp., and a backing has been proposed which incorporates two pairs of appropriate width flanges, which can be used to attach the backing to a wiper arm if it is of one of two width types . This backing has an open channel at a bottom of the backing into which a blade insert can be received. A first pair of the flanges is on the sides of the backing and situated directly adjacent the channel. These flanges are for a first width wiper arm. The backing then has a second open channel at the top into which a .

blade insert can be received. The second pair of flanges is also on the side of the backing and situated directly adjacent the second channel. The second flanges are for a second width wiper arm. In use, the blade insert is inserted into the appropriate open channel adjacent the required sized width pair of flanges. A wiper arm has claws into which the backing can be inserted and the head space above and between the claws is not sufficient to simply have a single channel for the blade insert and have the backing fitted directly with the claws for either a first width or second width wiper arm as the body of the backing cannot be received in that head space. Thus, the backing must be inverted if it is to be associated with the other width wiper arm, and the blade insert fitted in the other open channel. A backing of the above type is extremely troublesome and fiddly to fit. Moreover, it uses excessive plastics material in its construction.

OBJECT AND STATEMENT OF THE INVENTION The present invention has been devised to at least attempt to overcome the aforementioned problems.

Therefore, according to a first broad aspect of the present invention, there may be provided a backing for a windscreen wiper blade, said backing having a groove for receiving a blade insert and mounting means for permitting the backing to be held by a blade frame, said mounting means comprising a first pair of flanges over which claws from a blade frame can be received, and spaced from said first pair of flanges, a second pair of flanges over which claws from a smaller width blade frame can be received, the first pair of flanges being spaced near the bottom of the groove, and the second pair of flanges being spaced below the first pair of flanges, whereby a blade element received in said groove can be held by said backing for two

different sized width blade frames.

Preferably the first pair of flange means is integral with said backing, and said second pair of flange means is separate and retractably received to said backing so it can be extended when required.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention can be more clearly ascertained, examples of preferred embodiments will now be described with reference to the accompanying drawings wherein:

Figure 1 is an end view of a prior art arrangement;

Figure 2 is an end view of a further prior art arrangement;

Figure 3 is an end view of one example of a preferred backing;

Figure 4 is a perspective view of the backing shown in Figure 3; Figure 5 is an end view of a further example of a preferred backing;

Figure 6 is a perspective view of the backing shown in Figure 5.

Figure 7 is an end view of a further example of the preferred backing fitted in a smaller sized blade frame;

Figure 8 is a view similar to that of Figure 7 showing the embodiment fitted to a large sized blade frame; Figure 9 is an end view of a further example similar to that shown in Figures 7 and 8 but for use with double blade elements;

Figures 9 through 12 are views similar to that in figures 7, 8 and 9 but showing a modification;

Figure 13 is an end perspective view of an end

cap;

Figure 14 is a side view of the embodiment shown in Figures 7 through 8 fitted with the end cap; and

Figure 15 is a transverse cross-sectional view through Figure 14 along section line A-A showing how the end cap is located.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring now to Figure 1, where a prior art arrangement is shown, it can be seen that there are provided two blade elements 1 made of synthetic rubber material which is known in the windscreen wiper blade arts. The general shape of the transverse cross-section of the blade elements 1 is well known. The blade elements 1 are, in turn, held in a backing 3 which is made of a suitable plastics material such as of polycarbonate. The backing 1 has a pair of blade element receiving grooves 5 therein. The blade elements 1 are such that they can be slid along the grooves 5 so as to hold the blade elements 1 relative to the backing 3. The backing 3 is provided with holding means 7 in the form of a pair of flanges 11 with a pair of grooves 9. The grooves 9 are spaced behind the grooves 5 and the width of the backing 3 between the free ends of the flanges 11 corresponds with a predetermined width. In the prior art, this width has been either 6mm or 8mm although other widths are possible. A blade frame 11 is provided with claws 13 which are pre-made with a set distance between the free ends thereof. Thus, in the case where the backing 3 has a width between the free ends of the flanges 11 of 6mm then the spacing between the claws 13 is suitably sized and in the order of, say, 7mm. In the case where the backing 3 has a width between the free ends of the flanges 11 of 8mm then the spacing between the claws 13 is suitably sized, say in the order of 9mm. The free ends of the claws

are received within the grooves 9 to hold the backing 3 to the blade frame 11. Accordingly, for replacement purposes, it is necessary to stock appropriately sized backings 3 depending on whether the blade frame 11 is either for 6mm or 8mm backing.

The stocking of the suitable sized backings 3 has its obvious disadvantages.

Referring now to figure 2 there is shown a prior art backing which is disclosed in Australian Patent specification No. 78133/75 by Trico Products Corp.

In this backing there is provided a body 2 with a first channel 4 at a top of the backing body 2 and a second channel 6 at the bottom of the backing body 2. A blade insert 1 can be received in either of the channels 4 or 6. A first pair of mounting flanges 8 is mounted directly adjacent the open channel 4 for a first width wiper blade arm. A second pair of flanges 10 is mounted directly adjacent open channel 6 and is for a second width wiper blade arm. Wiper arm 11 has claws 13 which in the case of a smaller width wiper arm 11 fit directly under the pair of flanges 8 to hold the backing relative to the wiper arm 11. In this case, the blade insert is fitted in the open channel 6. When the blade insert 2 is for use with a wider width wiper blade arm 11 then the blade insert 1 is removed from channel 6 inserted in channel 4 and then the backing 2 and blade element 1 are inverted so that the pair of flanges 10 are uppermost relative to the pair of flanges 8 and then the claws 13 fitted over the pair of flanges 10. ^• ' It can be clearly seen that the head height above the pair of claws 13 is insufficient to accommodate the body 2 if the claws 13, in the representation shown in figure 2, are to be inserted over the flanges 10 with the open channel 4 being uppermost and within that head space. In the examples of the preferred embodiments

shown herein the above problems have been overcome.

Referring now to Figures 3 and 4, there is shown a backing 3 for a double blade element assembly similar to that shown in the prior art but drawn inverted by 180° . Here the backing 3 has a pair of grooves 5 into which the blade elements 1 can be received and held. The grooves are displaced across the backing from one another. The backing 3 then has a first pair of grooves 15 and spaced therefrom, but immediately thereto, a second pair of grooves 17. The grooves 15 and 17 are defined by respective first flanges

19 and second flanges 21, Thus, the width between the free ends of the second flanges 21 is less than the width between the ree ends of the first flanges 19. In the case where the backing 3 is for use with 7mm and 9mm blade frames 11, the spacing between the free ends of flanges 21 can be 6mm and the spacing between the free ends of flanges 19 can be 8mm. The spacing between flanges 19 and 21 can be of a suitable size as, for example, 1mm in order to receive the thickness of the claws of the wiper arm. Thus, the pair of flanges 19 is spaced near the bottom of grooves 5 and the second pair of flanges 21 is spaced below the flanges 19. This permits the blade elements to be received in the grooves 5 and held to the backing for two different sized width blade rames. Thus, the backing 3 can be utilised in a blade frame 11 which is either sized for 6mm or 8mm backing. In use, the claws 13 of the blade frame 11 are engaged over the appropriate ones of the pairs of first flanges 19 or second flanges 21 and into the respective grooves 15 and 16. The spacing between the flanges 19 and 21 is such that if the claws 13 are to engage with the flanges 19, they do not interfere with the fitting to the blade frame 11 itself. It should be noted they do not extend substantially into the central body space 23 (see Figure 1)

in the blade frame 11.

Thus, the pair of first flanges 19 are arranged substantially parallel to one another and co-planar and the second pair of flanges 21 are arranged substantially parallel to one another and co-planar but spaced from the first pair.

The embodiment of Figures 5 and 6 is substantially identical to that described in Figures 3 and 4 but here, the backing 3 is arranged for receiving only a single blade element 1. In this connection, the backing 3 has only a single groove 5 for receiving a single blade element 1. The backing is otherwise identical with the embodiments described in Figures 2 and 3 and therefore a further description has not been provided. Like numerical designations to like parts as shown in Figures 3 and 4 has been repeated in Figures 5 and 6.

The embodiment of Figures 7 and 8 is similar in concept to the previous embodiments except that the first flanges 19 are formed separately to the second flanges 21. Thus, the second flanges 21 are manufactured from a separate piece of material 30 such as polycarbonate and are retractably received relative to the first flanges 19. Here it can be seen that the second flanges 21 are formed of a generally "I-shaped" transverse cross-sectional extrusion. Thus, there are a first pair of flanges 21 and a further pair of further flanges 31. The backing 3 has a further groove means 33 therein opposite groove 5. The groove means 33 is closed by flanges 35. Thus, the extrusion comprising the second flanges 21 and the further flanges 31 can be received in the groove means 33 by sliding the extrusion from one end of the backing 3. The width between the free ends of the flanges 35 is approximately equal to the width of the bridging portion 37 between the second flanges 21 and the further flanges 31. The distance between the second

8 flanges 21 and the further flanges 31 is sufficient to enable the claws of the blade frame to locate on the inside faces of the second flanges 21 as shown, and clear the outside faces of the first flanges 19. Thus, when the extrusion, comprising the second flanges 21 and further flanges 31 are received in the backing 3 in the groove means 33 as shown in figure 7, the backing 3 is adapted to it to the narrower width blade frame 11.

Figure 8 shows the embodiment of Figure 7, fitted to a wider width blade frame 11. Here the extrusion comprising the second flanges 21 and further flanges 31 is retracted in the groove means 33 so that the inside faces of the second flanges 21 lie directly engaged against the outside face of the first flanges 19. Accordingly, the depth of the groove means 33 is sufficient to enable the bridging portion 37 of the extrusion to move into the groove means 33 for this purpose.

Referring now to Figure 9 which has like components to those shown in the previous embodiments of Figures 7 and 8, it can be seen that the arrangement is substantially identical to those embodiments of Figures 7 ^• and 8 except that the backing 3 is arranged to receive a pair of blade elements 1.

Referring now to figures 10, 11 and 12 there are disclosed embodiments similar to that in figures 7, 8 and 9. The only difference here being that the separate piece of material 30 is provided with a central generally "T" shaped recess 32. The recess 32 has a leg portion 34 which extends centrally down the bridging portion 37 and head portion 36 which extends within the further flanges 31. The recess 32 provides for flexibility of the backing piece 30 and assists with the blade elements 1 in conforming to the curvature of any window onto which they are fitted.

Referring now to Figures 13 and 14 there is shown an end cap which can be placed over the end of the backing shown in the embodiments of Figures 7 through 12 to inhibit against the extrusion comprising the second flanges 21 and the further flanges 31 from sliding from the backing 3. Here, the end cap 39 can be made of a suitable plastics material, such as polycarbonate, polyethylene, or metal or other suitable material. It can be seen that the end cap 39 is of generally box-shape configuration with an outer end wall 41, a top 43, two side walls 45 and a pair of spaced bottom flanges 47. The bottom flanges 47 are spaced to provide a channel 49 between the inside edge faces of the bottom flanges 47. The channel 49 is of a width which corresponds approximately to the width of a lowermost portion of the backing 3 adjacent the blade element 1. The width 51 between the inside faces of the side walls 45 corresponds approximately to the width of the outer edges between the first flanges 19. The depth 53 between the inside faces of the bottom flanges 47 and the top 43 is sufficient to enable the extrusion comprising the second pair of flanges 21 and the further flanges 31 to be extended as shown in dotted line in Figure 15, whilst the bottom flanges 47 still remain at the lower end of the backing 3 adjacent where the blade element 1 is fitted. Typically, the width of channel 49 and the width 51 are chosen to be a press-fit or force-fittable about the backing 3 in the relationship shown in Figure 15. If the end-cap 39 is made of metal, then it can be crimped in the position shown in Figure 15 over each end of the backing 3. Thus, when an end cap 39 is fitted to each end of the backing 3 as shown in Figures 14 and 15, the end cap 39 will prevent the' extrusion comprising the second flanges 21 and further flanges 31 from sliding within groove 33 and

keep that extrusion retained relative to the backing 3. The arrangement is such that it can be utilised with narrow- width blade frames 11 or wider width blade frames 11. Modifications may be made to the present invention as would be apparent to persons skilled in this art. For example, if it is subsequently perceived that there are a multiple number of widths required of the blade frame 11, then a corresponding number of suitably sized width pairs of flanges may be provided, each spaced from one another such that the largest width is closest to the blade elements 1 with the smallest width pair of flanges being furthermost from the blade elements 1.

These and other modifications may be made without departing from the ambit of the invention, the nature of which is to be determined from the foregoing description.