GB2234161A - Wiper blade assembly - Google Patents

Abstract

Effective and speedy clearance of windscreens of land, water and air vehicles is achieved by a twin-bladed wiper, the two blades 10, 20 being mounted side-by-side on a holder 30. Additional blades may be provided, similarly arranged. <IMAGE>

Description

WIPER BLADE ASSEMBLY This invention relates to a wiper blade assembly for use as part of a windscreen wiper of a vehicle. The invention is applicable to all forms of vehicle, namely all powered apparatus for locomotion over land, or water or in the air.

It is an object of the invention to provide a wiper blade assembly which will operate more efficiently and reliably than the assemblies known hitherto.

In this respect, a conventional wiper blade assembly, as used for example on an automobile windscreen wiper, consists of an elongate blade holder of relatively rigid plastics material, in engagement with a single blade of resilient material, such as rubber or synthetic rubber.

One know type of blade holder takes the form of a slotted channel section which has a substantially perpendicular projection provided on the external surface of its base web, opposite to the channel opening, and lateral flanges formed on this projection to enable engagement by connectors of a wiper arm assembly, whereon the blade assembly is to be mounted.

In this respect, the connectors are also of channel form and have, at their edges, inturned lips whereby they engage the lateral flanges by clipping thereover or by insertion thereon slidingly from one end. The blade is an elongage strip and has an enlarged base portion which is accomodated and retained within the channel of the aforesaid type of holder, the base portion connecting via a narrow neck, and an optional enlarged central region, to a tapering edge margin which provides the flexible wiping tip of the blade.

Another known type of blade holder takes the form of a pliable plastics strip, having a slot centrally along its length from closely adjacent one end to closely adjacent the other end, the two sides being additionally connected at intervals by curved bridging portions. A blade of similar form to that described above is then connected to the holder by its base portion being forced through the slot and retained at the side of the strip provided with the bridging portions. Connectors similarly clip onto this strip-like holder. Various other types of holder are also known.

It is usually found that several sweeps of a wiper blade across a windscreen are required to clear the windscreen of a film of moisture, e.g. as a vehicle is starting out on a winter#s morning, or when rain comes on. This is due to smearing of moisture and accumulated environmental dirt, insects, etc. by the wiper blade caused for example, by wear of the blade and/or slight misalignment of the component parts of the wiper structure. The smearing may be uneven and continuous: It may occur on alternate strokes, with a repeated sequence of smearing the screen as the wiper swings in one direction and clearing the screen in the opposite direction for a considerable period of time.

Conventional windscreen wipers are also quite inefficient at clearing frost from a screen.

Poor performance of windscreen wipers for any reason impairs visibility and is potentially hazardous, as well as causing delay, inconvenience and irritation to drivers of vehicles. This is equally true for aircraft, hovercraft, boats and ships as for land vehicles, such as automobiles, trucks and lorries.

In accordance with the present invention a wiper blasde assembly is provided which comprises at least two blades arranged side-by-side.

Compared to a conventional single-bladed wiper, the efficiency of operation of a wiper incorporating such a multiple blade assembly is greatly enhanced. For example, in practical tests a twin-bladed wiper has been found to clear a windscreen of moisture in one stroke, two at most, whereas many conventional single-bladed wipers take three, four or more strokes. Also, more importantly, perhaps, the occurance of continued patchy smearing or intermittent sequences of smear/clear as referred to above are drastically reduced, indeed, virtually prevented altogether. This is because any smearing or inadequate clearing by the first blade is compensated by the blade or blades which immediately follow it in the direction of sweep.

Further advantages of a twin-bladed wiper, which must apply equally, if not more so to wipers with more than two blades, are that frost is removed much more rapidly and that the rate of wear of the blade tips is reduced compared to a single bladed wiper.

In a particularly advantageous construction of wiper blade assembly in accordance with the invention the blades are mounted on a common holder. Such holder is preferably provided with a plurality of side-by-side channels for reception of base portions of the respective blades. In this respect, the holder conveniently comprises a single elongate element, as in a conventional blade assembly. A possible alternative, less likely in practice, is that the holder is constituted by separate sections, which may be adjoining, connected or spaced apart. Where the holder is a single element it conveniently consists of an extruded profile, since manufacture by extrusion is simple and inexpensive (not labour intensive once the initial die has been obtained). If the holder consists of several sections, each of these may be respective sections of extruded profile.

The configuration of the holder is advantageously such that the adjacent side-by-side channels provided therein have, in each case, a common intervening wall. This minimizes the material required for production of the holder.

In a practical embodiment, the holder is preferably so constructed as to be capable of holding blades of conventional, commercially available construction.

Furthermore, it is preferably also so constructed as to be readily and securely engageable by conventional connectors of a conventional wiper arm assembly. In this way, simply by replacement of a conventional blade holder with a holder for two or more blades, and obtaining an extra one or more blades to fit thereto, a conventional windscreen wiper can be converted to a twin - or multi-bladed wiper having all the attendant advantages of improved performance.

For engagement by connectors of a wiper arm assembly, the blade holder is conveniently provided with projecting means. In this respect, a particularly simple form of projecting means consists of a single ridge, usually centrally located, along the underside of the holder, opposite to the direction of projection of the blades, this ridge having a terminal enlargement, or outwardly extending flanges for engagement by connectors of a wiper arm assembly.

A more complex, yet more robust form of projecting means may consist of a pair of symmetrical flanges, preferably angled away from each other or having undercut recesses#or grooves at their sides remote from each other to facilitate secure engagement by conventional connectors. Such flanges may diverge relative to their plane of symmetry to impart additional resilience to the projecting means, further assisting secure and play-free engagement by conventional connectors.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a fragmentary perspective view showing only a small part of a windscreen wiper incorporating a first practical embodiment of a wiper blade assembly in accordance with the present invention; Fig. 2 is an end view, to an enlarged scale, of the wiper blade assembly forming part of the wiper shown in Fig. 1; Fig. 3 is a similar end view of a second embodiment of wiper blade assembly in accordance with the invention; and Fig. 4 is a fragmentary, smaller scale, perspective view of the holder of the assembly of Fig. 3.

With reference first of all to Fig. 2 a practical embodiment of the wiper blade assembly of the invention consists of two identical blades 10,20, of conventional form, mounted side-by-side and co-extensively on a holder 30.

The blades 10,20 consist of elongate strips of resilient material, preferably synthetic rubber. They have a constant cross-section, as illustrated. At one edge, each blade, has an enlarged base portion 12 in the manner of a cross-piece arranged transversely to the general plane of the blade. This base portion 12 connects via a first neck 13 to an enlarged central portion 14 which is provided at each side with a pair of fins, a and b. The central portion 14 connects via a second neck 15 to a tapering blade tip 16, which is designed for wiping across a substantially flat surface, such as a windscreen.

The holder 30 is an elongate extruded profile of relatively rigid plastics material, e.g. polyvinyl chloride or polyurethane. It defines two side-by-side channels 11,21 for reception of the base portions 12 of the respective blades 10,20. In this respect, the holder 30 has a base web 32 connecting respective narrow side walls 31,33, and a further wall 34 extending from the base web 32 midway between and substantially parallel to the side walls 31,33, the two channels 11,21 being defined between the respective side walls 31,33 and the common central wall 34. The side walls 31,33 each have inwardly projecting flanges 35 and the central wall 34 has a terminal flange 36 which projects in both directions to define with the opposing flanges 35 openings to the respective channels 11,21.

Provided on the external surface of the base web 32, opposite to the central wall 34, are a pair of divergent and outwardly angled flanges 37,38, which constitute projecting means for engagement by connectors 40 of a wiper arm assembly 50, as shown in Fig.l.

In use, the respective blades 10,20 are mounted on the holder 30 as shown in Fig. 2, with their base portions 12 accommodated in the channels 11,31. This may be accomplished by slidingly inserting the base portions 12 from one end of the holder 30. The holder 30 is then attached to the connectors 40 of a wiper arm assembly 50 (shown only partially in Fig. 1), the connectors 40 having inturned lips which engage the extremities of the respective flanges 37,38. This may be accomplished by snap fitting or by inserting the holder 30 slidingly from one end.

As shown in Fig. 1, connectors 40 are provided at both ends of secondary carrier members 42 (of which there are two) which are rockably mounted, as at 44, at one end of further larger secondary carrier members 43. The latter also have a connector at their other end for engagement of the extreme ends of the wiper blade assembly. The two larger secondary carriers are, in turn, rockably mounted at their central points on the ends of a primary carrier (not shown). the primary carrier is pivotally attached to a wiper arm which is adapted to be swingably mounted on a vehicle adjacent a windscreen. The wiper arm, the primary carrier and the respective secondary carrier members are herein referred to as a wiper arm assembly. An entire wiper consists of a blade assembly as illustrated in Fig. 2, connected to such a wiper arm assembly.

The wiper incorporating the twin-bladed assembly, as shown in the drawings, operates in the usual manner such that the blade tips 16 are swept across a windscreen in contact therewith, upon swinging to and fro of the wiper arm. The effectiveness of such blade assembly in clearing the windscreen of moisture or frost is, however, very much improved compared to a conventional single bladed assembly, as discussed in the introduction hereto.

The foregoing detailed description and drawings are illustrative, not limitative of the scope of the invention and very many variations are possible. For example, dealing firstly with the detailed configuration of the holder, the projecting means may alternatively comprise a pair of spaced apart flanges perpendicular to the base web. These may be angled outwardly or be provided with grooves or recesses on their faces directed away from each other for engagement by connectors. Alternatively, the projecting means may be in the form of flanges which are lateral extensions of the base web, or merely project from the side walls. In fact, the projecting means may be dispensed with altogether with the connectors engaging directly the body of the holder, e.g. by provision of grooves in the external side walls, or by enlargement of the connectors to embrace the entire channel-forming body.

Figs. 3 and 4 show a particularly simple and effective alternative form of holder 50, which, as shown, can be used for mounting wiper blades 10', 20' of similar configuration to those in Figs. 1 and 2. This holder 50 has a single central ridge 51 with outwardly extending flanges 52, constituting a T-section projection for engagement by connectors 40. This form of holder 50 is favourable as it has been found that it leads to a reduced tendancy to squeaking of the wiper as the blades are moved across a screen.

In other variants of holder, the adjacent channels need not have a common wall. Also three or more channels may be provided to accommodate three or more blades.

More generally, in other embodiments the holder need not be provided with channels: it could be in the form of a substantially flat strip provided with two or more co-extensive slots with the base portions of the blades retainable at one side of the slot and connecting via a neck to the tips at the other side.

It will be understood, therefore, that the fundamental requirement is only that two or more blades should be mounted side-by-side. Many alternative forms of the holder may be devised by those skilled in the art, adapted to the many different blade configurations currently available or yet to be designed.

Claims (13)

CLAIMS:

1. A wiper blade assembly comprising at least two blades arranged side-by-side.

2. An assembly as claimed in claim 1 wherein the blades are mounted on a common holder.

3. An assembly as claimed in claim 2 wherein the holder is provided with a plurality of side-by-side channels for reception of base portions of the respective blades.

4. An assembly as claimed in claim 3 wherein adjacent channels are separated by a common wall.

5. An assembly as claimed in claim 2, 3 or 4 wherein the holder comprises a single elongate element.

6. An assembly as claimed in any of claims 2 to 5 wherein the holder comprises an extruded profile.

7. An assembly as claimed in any of claims 2 to 6 wherein the holder has projecting means in the form of a pair of divergent flanges for engagement by connectors of a wiper arm assembly.

8. As assembly as claimed in any of claims 2 to 6 wherein the holder has projecting means in the form of a pair of outwardly angled flanges for engagement by connectors of a wiper arm assembly.

9. An assembly as claimed in any of claims 2 to 6 wherein the holder has projecting means in the form of a single ridge with outwardly extending flanges at each side for engagement by connectors of a wiper arm assembly.

10. An assembly as claimed in any of claims 2 to 6 wherein the holder has projecting means in the form of a single ridge with a terminal enlargement for engagement by connectors of a wiper arm assembly.

11. A windscreen wiper for a vehicle comprising a carrier pivotally mounted on a support arm, which is adapted to be swingably mounted on the vehicle, secondary carrier members rockably attached to the carrier, and a wiper blade assembly as claimed in any preceding claim connected to said secondary carrier members by a plurality of connectors.

12. A windscreen wiper for a vehicle comprising two blades arranged side-by-side.

13. A wiper blade assembly substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.