The present invention relates to improvements in wiper installations for use with windscreens.

The usual type of windscreen wiper installation comprises a wiper shaft which can be oscillated by a motor, a vriper arm extending radially from the shaf , and a wiper unit attached to the end of the wiper arm remote from the shaft. Means are provided for urging the wiper arm towards an associated windscreen. Operation of the motor causes the wiper unit to move ^' to and fro in a succession of cycles so that a wiper blade forming part of the wiper unit can wipe an arcuate area of the windscreen.

It is known, from German O fenlegungsschrift 2 619 -33j that a brush can be moved manually between positions in which either just the wiper blade is in contact with the windscreen, or both the wiper blade and the brush are in contact with the windscreen. In this latter position, the brush helps to remove debris from the windscreen which is not sufficiently removed by the wiper blade alone. A particular disadvantage of this known arrangement, however, is that whereas the scrubbing action of the brush is enhanced by the presence of water, during half.of each cycle of movement the wiper blade moves in front of the brush to clear water from the windscreen.

To overcome this disadvantage, the possibility of providing outlets for washing water in ^' the brush itself is proposed in the German publication, but there may be problems in making such provision in and supplying wate from an existing windscreen- washing system.

An aim of- the present invention has been to permit satisfactory operation even when there .are no outlets in the brush itself. In achieving that aim a further considerable advantage over known windscreen wiper installations has become apparent as is fully described hereinafter.

The essential feature of-the present invention is the provision of jacking means which, in use, can urge member towards and against a windscreen, then causing a wiper blade unit to be lifted away from the windscreen, and can cause or permit withdrawal of the member, there permitting the wiper blade unit to engage the windscree

Preferably, the jacking means includes a housing which is secured to a holder for attaching a wiper blad unit to a wiper arm.

The employment of jacking means, as distinct from the prior direct manual lowering or raising of the brus into or out of contact with the windscreen, enables a preferred arrangement to be utilised. In this the driv of the vehicle operates the member at will, or automatically according to the operating cycle of the wiper arm if suitable means are included in the installation, without stopping the vehicle or without the inconvenience of manipulating the member itself to bring it into or out of contact with the windscreen.

Such manipulation is particularly inconvenient on large vehicles where the wiper equipment cannot be reached by the driver when he is standing on the ground.

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There are two circumstances in ^' which the present invention is of particular value.

^• In one circumstance, the member is selectively brought into engagement with the windscreen instead of the wiper blade, and when in the form of a brush then serves to remove debris (notably insect debris) which a wiper blade does not satisfactorily remove.

In the other circumstance-* whether the member is a brush or otherwise the wiper blade is selectively lifted out of contact with the windscreen, such as at wiper stroke reversal, thus permitting water which would otherwise have tended to accumulate on a certain portion of the windscreen, under the combined effect of the movement of the vriper blade and the flow of air relatively to the windscreen, to pass under the wiper blade before the wiper blade is lowered to remove that water.

In both of these circumstances, the member should be capable of making sliding or rolling engagement with the windscreen without marking the windscreen, but the form that the member takes may be influenced, in particular applications, by which of those circumstances is the more important.

The member may for example, be a brush having tufts of natural or synthetic relatively long stiff bristles secured to a backing strip, or be a pad formed of a plastics material to present a regular array of relatively short protrusions, or be an elastomeric roller rotatable on an axis generally parallel to the wiper blade. One preferred form of the member consists- of a rigid backing strip which supports a scrubbing element, the scrubbing element having a body which is resilient to a substantial extent in a direction to and from the backing strip, and the body carrying a working facing on which are numerous scrubbing projections.

It has been found that certain materials which are suitable for the working facing are commercially available.

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- -- - -- under the name "Velcro" (Registered Trade Mark) from Selectus Ltd-, of Stoke-on-Trent, England.

The member is preferably of equivalent length to the wiper blade, and is preferably arranged to be general parallel to the wiper blade, but there may be more than one such member, and the members spaced apart from one another in a direction parallel to the wiper blade, particularly if the main purpose of the members is merely to lift the wiper blade, in which case the members may be operated by their own individual jacking means, or may be linked together for operation by a common jacking means.

It will be apparent that, in any installation according to the present invention, the jacking means may be single-acting or double-acting, and may be operated hydraulically, for example by water from a windscreen washer system, or pneumatically, or may be operated by a solenoid with suitable control switches.

It will further be apparent that, although this invention has been particularly developed in relation to heavy duty wipers, such as are installed on the cabs of railway vehicles, and of large road vehicles, it is applicable to vehicles in general, regardless of the size of their windscreensand whether the windscreens are flat or curved. Examples of several embodiments of the present invention will now be described with reference to the accompanying drawings, in which:-

Figure 1 is a plan view of a windscreen wiper installation in accordance with the present invention; Figure 2 is a side elevation in the direction of the arrow II in Figure;

Figure 3 is a cross-section on the line III-III of Figure 2;

Figure 4 is an end elevation, seen in the directi of Figure 3, showing the member in action with the wiper blade raised; and

Figures 5 to 7 are all fragmentary perspective

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views of alternative forms for the member.

Referring to Figures 1 to 4, a windscreen wiper installation is shown for use in conjunction with a flat windscreen on the cab of a railway vehicle. Only the outer end is shown of a wiper arm 2, whose other end is secured to a vriper shaft (not shown) adapted to be oscillated by a motor. Said outer end of the wiper - arm- 2 terminates in a boss 4 to which is fixed a holder ' or clip 6. Into this clip 6 is fitted a backing strip 8 of a wiper unit, which includes a wiper blade 10 carried by the strip 8. The wiper blade 10 is urged towards the windscreen by a wiper arm spring (also not shown) the loading of which is pre-stressed.

The components so far described can be those currently in use. The installation is modified, in accordance with the present invention, by the following further components.

A plate 12 serves as a means of mounting a jack 14 on the clip 6. The plate 12 is secured to the clip 6 by a single bolt 16, and has a lip 18 which fits the contour of the clip to prevent rocking. The jack 14 has a housing 20 which is secured to the plate 12 by two screws 22, the right-hand screw 22 (as shown in Figure 2) passing through an elongate slot 24 in the plate 12, for adjustment as described below.

The housing 20 defines a cylinder 26 which is closed at its lower end by a cover 28. In the example shown, the jack 14 is a pneumatically-actuated single-acting jack, with spring return. A piston rod 30 passes through the cover 28, and carries a piston 32 with a sealing ring 34. The return spring is a coil spring 37 confined between the piston and the cover 28.

The upper end of the cylinder 26 is connected by a passage 36 to a hose 38, through which air .can be supplied and exhausted, as described below.

Attached to the lower end of the piston rod 30 is a block 40., to which in turn is attached a backing, strip 42 of an elongate brush 44 with stiff bristles.

The normal condition of the jack 14 is as shown ^' in Figures 1, 2 and 3. that is to say with the piston 32 and brush 44 in an uppermost position. There is then clearance 46 between the brush 44 and windscreen surface 48. This clearance 46 is however a shorter distance than the stroke of the piston 32. In this normal condition, the wiper blade 10 is in engagement with the windscreen surface 48. Oscillatio of the wiper arm 2 in the normal manner by a wiper shaft will cause the wiper blade 10 to wipe the screen in the normal manner. Whenever there is a desire to remove debris which has not been removed by the vriper blade, a person driving the vehicle can cause compressed air to be admitted via the hose 38 to the upper end of the cylinder 26. This causes downward movement (as seen in Figures 2, 3 and 4) of the brush 44 until the brush 44 engages the windscreen surface 48, follovred by upward movement of the housing 20 carrying with it the wiper arm 2 and the wiper blade 10. Consequently, there is then clearance at 49 between the vriper blade 10 and the windscreen surface 48. In practice, the operation of the jack in this way should be associated with operation of a windscreen washer. The windscreen washer may be of the type with fixed jets, or of the type with jets carried by the wiper arm, or be capable of delivering vrater through a perforated pipe extending along the length of the brush. A few cycles of movement of brush 44 by the wiper arm should be sufficient to dislodge debris.

Release of compressed air from the upper end of the cylinder 26 via the. hose 38 enables the condition of Figures 1, 2 and 3 to be quickly restored by the action of the return spring 37. Thereupon the first cycle of operation of the wiper blade 10 will remove water and the

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traces of debris, leaving a clear view.

In order to obtain a uniform action of the brush 44 along its length, it is desirable for the clearance 46 to be of uniform extent throughout its length in the normal condition of Figures 1, 2 and 3. The slot 24 in the plate 12 to accommodate one of the screws 22 permits adjustment- to be made to achieve this uniform clearance. That is' to say, the slot 24 in the plate 12 permits the brush 44 to be adjustably securable about an axis at right angles to the line of action of the jack 14 so that the brush 44 can be secured to lie parallel to the windscreen surface 48.

If, at the end of a stroke, one end of the brush should encounter the rim of a windscreen, the _. piston rod 30 can pivot slightly around its ovm axis, thus allowing that end of the brush to approach the wiper blacking strip 8. This means that installation of the jack 14 and the brush 44 does not necessitate any adjustment in the normal length of stroke of the wiper installation. It will be appreciated that the axis of the pivot rod 30 is coincident with the line of action of the jack 14.

A particularly preferred form of the member is not the brush 44 shown in Figures 1 to 4 but a brush 50 as shown in Figure 5-

The brush 50 includes a clip 52 aecurable by a releasable fastening to the lower end ofihe piston rod of the above-described jack or to any other appropriate jacking means. The clip 52 is fastened by a rivet 5 to a backing strip 56. This backing strip is of metal, of uniform cross-section, in the general form of an inverted channel, with a somewhat contracted mouth.

Body 58 of the brush is an extrusion of rubber, in the form of a resilient tube with an integral upwardly- extending flange 60. This flange is gripped in the backing strip 56. The body 58 is cut to the required length,

and the two ends 62 of the tube are open. Around the exposed lower part of. the tube, and trapped in position by the contracted mouth of. the backing strip 56 is a facing material 64. The preferred facing material is known as "type 4 hookless Velcro" (Registered Trade

Mark) . The surface appearance in the drawing is purely symbolic. In fact the surface resembles a forest of a very large number of small, bristle-like projections from a flexible strip. The facing material 64 has little affect on the resilience of brush 50 as a vrhole.

When brush 50 is in its operative position under pressure exerted by the vriper arm, the resilience of the brush enables contact to be made with the windscreen by the vrhole length of the brush, which is advantageous. Such complete- contact is difficult to achieve with the stiff bristle brush 44 even on a flat vrindscreen.

The resilience of brush 50 is attributable to the tubular nature of the body 58 in conjunction with the grade of rubber of which it is made. In consequence, throughout the oscillation of the brush 50 by the wiper arm, the working facing engages the windscreen with a force lying within a range which will give rise to a scrubbing action and the consequent dislodging of debris, particularly insect debris. The scrubbing action is enhanced by the presence of water on the vrindscreen. This may be applied by a spray, and spread by the wiper blade, brush 50 being held clear of the windscreen by the jacking means. Afterwards, the jacking means is operated to bring brush 50 into contact with the windscreen to perform a scrubbing action during vriper arm operation.

In brush 70 shown in Figure 6, the tubular body is replaced by a body 72 which is a moulding of rubber. It includes an upper strip 74 and a lower strip 76, linked together by a pluralit.*- of inclined webs 78.

These webs 78 render the body resilient to a substantial

extent in a direction to and from the backing strip 56. The upper. strip 74- carries a flange 6θ _t which is gripped by the backing strip 56. The lower strip 76 is semi- -circular in cross-section, with its curved surface 5 downwards, and the working facing 64 is secured by adhesive to this semi-cylindrical surface.

The brushes 44, 50 and 70 so far described have all been primarily intended for use in association with flat vrindscreens. The present invention may also be

10 utilised however with curved windscreens. To suit a curved windscreen, the back of the brush should be arched perceptibly along its length in the manner of a comparable wiper blade, and have resilience in the plane of the arch and stiffness at right angles to that plane,.

15 or be supported by a conventional harness to impart such arch form, resilience and lateral stiffness.

A member 80 which is suitable for use in association with a curved windscreen is shown schematically in Figure 7.

20 The member 80 includes a facing 82 of the above- -mentioned "type 4 hookless Velcro" (Registered Trade Mark) , the facing 82 being secured by adhesive to the lower face of an elongate pad 84 of neoprene, whose upper face is formed with an upstanding flange 86 having

25 a pair of opposed longitudinally extending grooves

88. Longitudinally spaced pairs of opposed fingers 90 (only one pair being shown) , constituting vertebra and being carried by a conventional harness 92, enter the grooves 88 to impart the required resilient arch form

30 and lateral stiffness to the member 80.

For situations in which it is desired to permit vrater to pass between the vriper blade and the windscreen, any of the above-described brushes may be used, as the water can leak past their bristles or scrubbing

35 projections even when they contact the windscreen, and they can slide on the windscreen without scratching, and furthermore they are not likely to accumulate grit

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which might scratch the windscreen.

The purpose of the jacking means is then to raise the wiper blade 10 away from the windscreen, thus providing a clearance such as the clearance 49 shown in Figure 4, at suitable moments during operation. Preferably, in this case, the supply of compressed air via the hose 38 to the top of the cylinder 26 is under automatic control, in association with the operation of the motor which imparts oscillating motion to the wiper shaft carrying the wiper arm 2. It has been found that, where a windscreen is inclined upwards and rearwards, and a wiper shaft is below the windscreen, then, during the parts of its cycle during which the wiper blade is approaching an end of a stroke, this being. a condition in which the length of the wiper blade is becoming progressively nearer the horizontal, the wiper blade tends to push ahead of it a quantity of water which has accumulated and is confined against the wiper blade by the air flovr upwards over the windscreen, and upon reversal of the movement of the wiper blade at the end of its stroke, this water follows the wiper blade, thus obscuring the portion of the windscreen which has just been wiped.

We have found that if the wiper blade is raised from the windscreen for a short angular distance as the blade is approaching, the end of a stroke at least on the driver's side of the vehicle, then the air flow due to forward motion of the vehicle causes the water to pass under the iper blade, whereupon, if the wiper blade is then returned to contact the vrindscreen, and then performs its next stroke, it carries away water accumulation from the area which hitherto tended to be obscured.

For the purpose of clearing away this water accumulation as aforesaid, once in each complete cycle of operation of the vriper arm, the vriper shaft may carry

a cam which cooperates vrith a pawl to operate a valve controlling admission and release of compressed air to the hose 38 leading to the jack 14. By this means, the jack is actuated as -the wiper blade is approaching the end of a stroke, say 15° before the end, and the ack is released a few degrees before or at or a few degrees after completion of the wiper blade stroke. If it is desired to clear -way water ^' accumulation twice in each cycle of the. iper arm operation, at say opposite ends of each stroke, a second pawl is also arranged suitably to cooperate with the cam and the valve.

Such operations to clear a ay water accumulation occur throughout the operation of the wiper arm, that _, is to say both under conditions of rain, and under conditions of the use of a windscreen washer to remove debris of the kind which can be cleared by the wiper blade in conjunction with washing water.