GB2352966A - Wiper assembly with resilient suspension means between blade and blade carrier - Google Patents

Abstract

A windscreen wiper blade assembly for heavy duty, eg. marine, use comprises a flexible extruded blade 1 (1a, 1b) with stropping action profile, a rigid extrusion blade carrier 2 (or 2,3 fig.2), means 6 for connection of the assembly to a driving mechanism, and resilient suspension means 10 disposed between blade 1 and carrier 2 to permit relative translational movement between the two. This movement may enhance the effectiveness of wiping in the case that the blade is very long and/or used on a large windscreen with substantial surface variations. The suspension means 10, may comprise mechanical spring means which may comprise one or more spring elements such as leaf springs (11, fig.5). Free ends of the spring elements may be connected to the blade 1/carrier 2 by bearing means such as fingers (12, fig.5) Separate pluralities of spring elements may be carried either by the blade or the carrier. An alternative, the suspension means may comprise an enclosed fluid or foam material enclosed within the extrusion carrier 2.

Description

2352966 "Wiper Blades for Heavy Duty Use" The present invention relates to

wiper blades for use primarily in heavy environmental conditions such as on ships where the wiper blade has to deal with wind, sea and salt and to wipe a relatively large area. The invention is also applicable in other circumstances where large areas are to be wiped and robustness is required, for example on trains and in large automotive applications.

For example if a wiper blade has to wipe the area in front of the bridge of a ship the blade may have to be up to 1500 mm long. The screen to be wiped may be nominally flat but over such a distance and area there will inevitably be surface variations.

Various complex structures are used on existing automotive blades however they are not designed to withstand, for example, a marine environment, and so would have a short working life in that environment. For marine use such blades would have to be of marine- compatible structural materials such as stainless steel to avoid corrosion, and since access to the outside of the windscreen on a ship is often difficult the blades need to have a long working lif e to minimise the times when replacements are needed. A long working life is also important in the case of wipers used on trains and in 2 large automotive applications.

With these objectives in mind it is desirable that the blade should be of simple manufacture so as to be suitably robust without being unduly costly to 5 manufacture.

The blade should be environmentally compatible this means, in particular for marine applications, that the blade should not deteriorate in sunlight, high ozone, ultraviolet and saline conditions and should be able to survive being subjected to both low and high temperatures.

The blade desirably should be capable of being misused. Thus, wipers are of ten lef t running af ter sea spray or rain has ceased and then the wiper blade may leave rubber deposits on the windscreen. This then results in degradation of the quality of performance.

The blade should have a long working life and be of a heavy duty specification. It needs to withstand rough treatment, it should not tear when faced with impact with edges of frames, and it should be capable of operation without damage in frozen conditions.

The blade should be simple to manufacture and to this end should ideally be a blade which can be cut to length from appropriate extrusions to which a backing and end stops can be applied.

3 other more specific requirements include the following:

A large nominally flat glass screen of, for example, a ship will not be entirely flat and therefore if a very long blade is to be used it should have enough compliance to be able to cope with non-flat areas of glass.

it is desirable that so-called stick-slip characteristics are favourable. Otherwise, the wiper can hop when at low speed due to being on the threshold of frictional stick situations, so leaving a "streaked" or "lined" swept area.

The blade needs to be able to "strop" that is to say it needs to be able to flip from side to side so that whichever direction it is moving it will be in a dragging configuration. Also, the blade's operation should not involve noise particularly in the transition between wet and dry screen use.

It is desirable that a high quality of wipe is achieved, that is that the blade remains in contact with the screen so that the operator, particularly when close to the screen has a clear view.

It is desirable in order to achieve some of the above objectives that the blade should have a relatively aerodynamic form. Particularly in the case of a large blade, there is the difficulty that if the shape is 4 incorrect, the flow of air across the blade can result in lift whereby reducing the wiping effectiveness. This again makes a relatively simple structure preferable.

In some existing blades a wiping portion of the blade comprises a wide strip of rubber protruding from a rigid carrier. During wiping the strip bends to adopt a trailing position. Because the strip is wide a relatively large variation in bend can take up undulations in the screen. However, there is a limit to the undulations which can be taken up in this way and the wide strip presents a large surface on which undesirable aerodynamic force can act.

The present invention therefore sets out to provide a blade which meets at least some of these objectives and avoids at least some of the problems of the prior art.

Accordingly the invention provides a windscreen wiper blade assembly for heavy duty use, comprising a blade profile extrusion of flexible rubbery material and having a profile to provide a stropping wipe to a screen to be wiped, a relatively rigid extrusion carrier carrying said blade profile extrusion and having means for attachment to a driving mechanism wherein suspension means are disposed at the rigid extrusion carrier for allowing and resiliently controlling translational movement of a wiping portion of the blade profile extrusion towards and away from the rigid extrusion carrier.

Such an arrangement can be used to allow relatively large undulations to be taken up whilst leading to a compact design which serves to minimise undesirable aerodynamic effects (for example lift and drag) and gives less obstruction to vision as well as a smaller area on which ice can collect.

The suspension means may comprise mechanical spring means. The mechanical spring means may comprise at least one plurality of spring elements. Each spring element may comprise a leafspring.

The assembly can be arranged so that free ends of the spring elements contact with and, in use, ride on, opposing bearing means which are mounted on the extrusion carrier or blade profile extrusion as appropriate.

The assembly may comprise engaging means mounted on the extrusion carrier and/or blade profile extrusion for engaging with free ends of the spring elements. In some embodiments the spring elements serve to connect the extrusion carrier and the blade profile extrusion.

The or each plurality of spring elements may be formed from a respective single piece of sheet material. Typically this material will be metallic, for example stainless steel. The bearing means may comprise at least 6 one of the pieces of sheet material. This reduces the number of components required and the spring material is also likely to be suitable as a bearing surface, for example stainless steel is both springy and extremely 5 tough.

A first plurality of spring elements may be carried on the extrusion carrier and a second plurality of spring elements may be carried on the blade profile extrusion. These will typically oppose one another suitably so that where the spring elements are formed of respective pieces of sheet material, the free ends of one set of springs may ride on the sheet material from which the other set of springs are formed.

The blade profile extrusion may comprise the wiping portion and a suspension portion. The suspension means may comprise the suspension portion. The suspension means may be disposed within the carrier extrusion. This enhances the compactness and robustness of the design. The suspension means may comprise suspension media, which may be contained wholly within the carrier extrusion. Preferably said translational movement is substantially linear. Said blade profile extrusion may incorporate laterally extending resilient suspension supports enabling the wiping portion to be capable of resiliently controlled transverse movement relative to the screen to 7 be wiped. The extrusion carrier will generally be of a marine compatible structural material such as stainless steel, aluminium. or an appropriate plastic composite so as to be relatively rigid in use as well as being corrosive resistant to the elements. The extrusion carrier may be of a generally U-shaped profile so as to enclose and carry the blade profile extrusion. Preferably the shape of the extrusion carrier is chosen to not only enable the blade prof ile extrusion and the suspension means to be accommodated, but to also reduce the possibility that the exterior of the blade is subjected to undesired aerodynamic lift effects. The extrusion carrier may be of a substantially square U-shaped profile.

There may be a pair of spaced lateral supports on each side of a centre line of the blade profile extrusion. Each pair of lateral supports may be joined at external extremities by longitudinal panels closely fitting within said extrusion carrier.

Preferably the suspension means does not include any complex components which if present would tend to seize up, corrode or fail leading to a shorter working life.

However, the suspension means may comprise one or more plastic hinge.

The transverse movement of the wiping portion may 8 be controlled by one of or a combination of flexure of the lateral supports, resilient members such as spring elements, the action of an enclosed fluid for example air, a liquid/gel or an enclosed foam material. The enclosed material may provide or add to the resilient resistance, and may also incorporate damping dependent on the nature of the material. Where the enclosed material is a fluid, especially a liquid/gel, the fluid will move in such a way that pressure throughout the fluid tends to equalise. Thus if the wiping portion at one region is forced towards the extrusion carrier by an undulation in a screen other regions of the wiping portion will be forced away from the extrusion carrier into firmer contact with the screen. In this way the wiping portion will tend to adjust to the form of the screen being wiped. Embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: 20 Figures 1A and 1B show cross-sections of a wiper blade assembly; Figure 2 shows a wiper blade assembly in side elevation which can be used for large screens; Figure 3 shows a wiper blade assembly in side elevation of a more conventional form; 9 Figure 4 shows a sectional view of another wiper blade assembly; Figure 5 shows a section on line V-V of the wiper blade assembly shown in figure 4; and Figures 6A to 6C show a plan view, an end view and a side view of a spring element of the assembly shown in figure 4.

Referring to Figure 2, a wiper blade assembly is shown which is particularly suitable for use as a very long blade to be used on a large screen area. Thus the blade may be up to 1500 mm long and in consequence the drawing is not to scale.

The assembly shown comprises a blade profile extrusion I of flexible rubbery material, for example a material formed from a marine grade rubber compound such as polychloroprene, and this extrusion is carried by a pair of rigid carrier extrusions 2 and 3 each extending half the operative length of the blade so as to leave a central unsupported gap 4. The blade profile extrusion 1 comprises a wiping portion la and a suspension portion 1b.

The two rigid carrier extrusions 2, 3 of stainless steel, aluminium or another marine compatible structural material are carried by a linking carrier member 5 of similar material which itself is carried by an arm 6 which is arranged to be connected to a conventional driving mechanism for the wiper system.

The linking carrier member 5 is connected to each of the rigid carrier extrusions 2, 3 by a flexible link 7 which in each case, in conjunction with the lower shape of the blade profile is such as to enable the blade to strop, that is to say to flip over from side to side so that during wiping the blade is always lagging from the direction in which the blade is moving. The flexible link 7 is in each case of conventional form.

Figures 1A and 1B, show the blade prof ile 1 of a suitable rubber material which includes on each side a pair of lateral resilient ribs 8 in each case connecting the blade prof ile to edge panels 9 which in turn are held within approximately square section rigid carrier extrusion 2. Figures 1A and 1B show the blade arrangement flexing between two positions to accommodate different levels of glass on the surface being wiped.

In order to assist this resilient movement, a space behind the profile and within the rigid extrusion 2 carries a suspension media at 10, which may be foam rubber or it may be a gel or the zone may be simply a void, i. e. forming an air suspension. The suspension media may be disposed within a bag consisting of an 11 appropriate membrane to form a sausage-like element which is locatable in the rigid extrusion 2. The blade prof ile 1 need not be f ixed to the rigid extrusion 2 and is retained in position by virtue of lips 2a at the open face of the rigid extrusion 2 and the presence of the suspension media 10.

It will be noted that the prof ile of the rigid carrier extrusion shown in the drawings is substantially rectangular or square-shaped. In practice the profile of the rigid carrier extrusion is chosen for a particular application to minimise aerodynamic lifting forces which occur in use.

It will also be noted that the transverse width of the portion of the blade profile I which projects from the carrier extrusion 2 is small relative to the corresponding portion of a blade which has no suspension system and relies on the compliance in a bent wiping portion to take up undulations in the glass to be wiped. This reduces the area on which wind can act to generate undesirably aerodynamic forces and so reduces the tendency for lift. In the present case it will be noted that whilst the wiping portion la may bend to some extent to help take up undulations it is the linear translational movement of the wiping portion la as a whole which ensures that the blade remains in contact 12 with the screen when undulations are encountered. The compact design has further advantages as it leads to reduced drag which can allow smaller driving motors to be used and means that there is less obstruction to 5 vision and a smaller area on which ice can collect.

Referring again to Figure 2, it will be noted that there is a gap 4 between the rigid carrier extrusions 2 and 3. This helps the blade prof ile 1 to f lex both laterally and transversely in use so that the blade is better able to follow a lack of flatness in a screen being wiped.

While the blade profile shown in Figures 1A and 1B can be used with the wiper assembly shown in Figure 2, the invention is not limited to use of such a construction. Thus blade constructions which in side elevation are quite conventional can also be used with these profiles, for example as shown in Figure 3 where similar components have the same reference numerals. Such an arrangement (as shown in Figure 3) will be used when a smaller area is to be covered. The connection point between the linking carrier member 5 and the rigid extrusion 2 may be located at the Airy points of the rigid extrusion 2.

Other suspension systems are envisaged, for example the use of mechanical springs within the carrier 13 extension or the use of a piston type construction where the suspension portion comprises a piston which moves within the rigid extrusion. In some alternatives all or some of the lateral ribs 8 may be dispensed with.

Figures 4, 5 and 6A to 6C show another wiper blade assembly in which the suspension means comprises mechanical spring means. There are similarities between this assembly and that shown in f igures 1 to 3 and the same reference numerals will be used where appropriate.

In this embodiment the extrusion carrier 2 is formed of a bar of suitable material such as aluminium which supports the blade profile 1 via a pair of leaf spring strips 10. Each of the strips 10 is formed of a single piece of sheet metal, such as stainless steel, which is punched and bent to give the necessary shape. Although Figure 5 shows only a single leafspring 11 for each of the strips 10, there are a plurality of longitudinally arranged and spaced leafsprings 11 in each strip 10.

Figures 6A to 6C more clearly show a typical portion 20 of one of the strips 10. Each strip 10 includes a series of engaging fingers 12 for receiving the free end lla of an opposing leafspring 11, and associated bearing surfaces 13 on which the respective free ends 11a ride in use.

As can be seen in Figure 4, one of the strips 10 is 14 mounted on the extrusion carrier 2 and one on the blade profile 1. Edge portions 14 of each strip 10 are disposed in respective receiving recesses provided in the extrusion carrier 2 and blade profile 1.

It can be seen from Figure 5 that, the extrusion carrier 2 and blade profile 1 are connected via the engagement between the leafsprings 11 of each strip 10 and fingers 12 of the respective other strip 10. Further, the blade profile 1 is urged against the screen by the action of the leafsprings 11. The system has good wear characteristics because the action of the free ends of leafsprings 11a is on the material of the other strip 10. This is particularly important because relative transverse movement between the blade profile 1 and the extrusion carrier 2, as the blade passes over bumps, will cause the free ends 11a to slide in a longitudinal direction. The blade assembly will typically be designed so that the leafsprings 11 can accommodate 3 to 4 mm of movement between the blade profile 1 and extrusion carrier 2.

It can be advantageous if some form of bearing surface is provided even in alternatives where the free ends cannot bear on an opposing springstrip. This is to avoid free ends of the springs rubbing on the extrusion carrier and, particularly, on the blade profile.

It is not essential that two sets of spring elements are provided. It is sufficient, for example, if a set of springs are mounted on the profile 1 for engagement with and action on the extrusion carrier 2 or vice versa. For example, a strip including springs may be mounted on the profile 1 and the free ends of the springs may be arranged to be engagable with the extrusion carrier 2.

Although not shown in the drawings, the extrusion carrier 2 may include depending sidewalls so as to be generally U-shaped and surround the leafspring strips 10 and possibly an upper piston-like portion 1c of the blade profile 1.

In some cases it will be possible to incorporate some of the suspension techniques described in relation to Figures la and lb with those described in relation to Figures 4 to 6. For example, mechanical spring resistance may be combined with fluid resistance and/or resistance in the profile itself.

In any of the above cases, the blade profile may be formed of two different materials co-extruded to give for example, compliance in the suspension portion lb and a more rigid wiping portion la.

Where an arrangement such as that shown in Figure 3 is used there may be a single attachment point between the carrier extrusion 2 and the arm 6. In both the 16 arrangement shown in Figure 2 and that shown in Figure 3 the carrier extrusion(s) may be rolled so as to have a slightly bowed shape when not under stress such that they become essentially straight when the blade is in 5 use.

In general terms the blades described in this application are intended for use with large and nominally flat screens. It is the relatively local unevenness and undulations in such screens which the suspension systems of this application are intended to take up.

Claims (19)

CLAIMS:

1. A windscreen wiper blade assembly for heavy duty use, comprising a blade profile extrusion of flexible rubbery material and having a profile to provide a stropping wipe to a screen to be wiped, a relatively rigid extrusion carrier carrying said blade profile extrusion and having means for attachment to a driving mechanism wherein suspension means are disposed at the rigid extrusion carrier for allowing and resiliently controlling translational movement of a wiping portion of the blade profile extrusion towards and/or away from the rigid extrusion carrier.

2. A windscreen wiper blade assembly according to Claim 1 in which the suspension means comprises mechanical spring means.

3. A windscreen wiper blade assembly according to Claim 2 in which the mechanical spring means comprises at least one plurality of spring elements.

4. A windscreen wiper blade assembly according to Claim 3 in which free ends of the spring elements contact with and, in use, ride on, opposing bearing 18 means which are mounted on the extrusion carrier and/or blade profile extrusion.

5. A windscreen wiper blade assembly according to Claim 3 or Claim 4 comprising engaging means disposed at the extrusion carrier and/or blade profile extrusion for engaging with free ends of the spring elements.

6. A windscreen wiper blade assembly according to any one of Claims 3, 4 or 5 in which the or each plurality of spring elements is formed from a respective single piece of sheet material.

7. A windscreen wiper blade assembly according to Claim 6 when dependent on claim 4 in which the bearing means comprise at least one of said pieces of sheet material.

8. A windscreen wiper blade assembly according to any one of Claims 3 to 7 in which a first plurality of spring elements is carried on the extrusion carrier and a second plurality of spring elements is carried on the blade profile extrusion. 25 19

9. A windscreen wiper blade assembly according to any preceding Claim in which the suspension means is disposed within the carrier extrusion.

10. A windscreen wiper blade assembly according to any preceding claim in which the blade profile extrusion incorporates laterally extending resilient suspension supports enabling the wiping portion to be capable of resiliently controlled transverse movement relative to the screen to be wiped.

11. A windscreen wiper blade assembly according to Claim 10 comprising a pair of spaced lateral supports on each side of a centre line of the blade profile extrusion.

12. A windscreen wiper blade assembly according to Claim 11 in which each pair of lateral supports is joined at external extremities by longitudinal panels closely fitting within said extrusion carrier.

13. A windscreen wiper blade assembly according to any preceding claim in which the shape of the extrusion carrier is chosen to enable the blade profile extrusion and the suspension means to be accommodated, and to reduce the possibility that the exterior of the blade assembly is subjected to undesired aerodynamic lift effects.

14. A windscreen wiper blade assembly according to Claim 1 in which the suspension means comprises an enclosed fluid or an enclosed foam material, in each case being enclosed within the extrusion carrier.

15. A windscreen wiper blade assembly according to Claim 14 in which the enclosed material is a fluid, and the arrangement is such that the fluid can move in such a way that pressure throughout the fluid tends to equalise, so that if the wiping portion at one region is forced towards the extrusion carrier by an undulation in a screen, other regions of the wiping portion will be forced away from the extrusion carrier into firmer contact with the screen.

16. A windscreen wiper blade assembly according to any preceding claim in which the blade profile extrusion comprises the wiping portion and a suspension portion and the suspension means comprise the suspension portion.

21

17. A windscreen wiper blade assembly according to any preceding claim in which the translational movement is substantially linear.

18. A windscreen wiper blade assembly according to any preceding claim in which the extrusion carrier is of a marine compatible structural material such as stainless steel, aluminium. or an appropriate plastic composite so as to be relatively rigid in use as well 10 as being corrosive resistant to the elements.

19. A windscreen wiper blade assembly according to any preceding claim in which the extrusion carrier is of a generally U-shaped profile. 15