GB2477563A - Winscreen wiper apparatus - Google Patents

Abstract

A windscreen wiper apparatus 20, movable between a stowed and an open position and adapted for cleaning a vehicle windscreen screen, the apparatus having: a wiper blade 29; a support structure for supporting the wiper blade on a wiper arm 27; and at least one resilient bump-stop 21, wherein said bump-stop extends beyond the wiper blade and is configured to contact the frame 3 of the windscreen so as to limit the excursion of the wiper blade in use.

Description

WINDSCREEN WIPER APPARATUS

Field of the invention.

The invention is concerned with improvements in windscreen wipers for vehicles and particularly, but not exclusively, to windscreen wipers optimised for use in clearing snow, salt and/or dirt from a vehicle windscreen. Aspects of the invention relate to an apparatus, to a system and to a vehicle.

Background of the invention.

Modern passenger and commercial vehicles intended for use on public roads are typically fitted with windscreen wipers. The vehicle may be provided with one or more wipers arranged to clear rain, snow or other contaminants from the windscreen or other transparent member to maintain driver visibility while operating the vehicle.

In known vehicle wiper systems, a wiper arm is mounted to an actuator at one end and supports a wiper blade at the other end. The wiper arm is biased towards the surface of the screen so as to keep the wiper blade in contact with the surface of the screen in use. The pressure exerted on the wiper blade by the arm affects wiper performance and the wear rate of the wiper blade. If too much pressure is applied, the blade will wear prematurely; if too little pressure is applied, on the other hand, the wiper blade will not clear the surface efficiently, allowing contaminants to smear on the screen, reducing driver visibility.

To support the wiper blade evenly, some wiper systems use a wiper support structure between the wiper arm and the wiper blade. The support structure may take the form of a resilient, bow-shaped frame arranged to distribute the biasing force from the arm evenly across the entire length of the wiper blade.

In use, the actuator drives a shaft on which the wiper arm is mounted. The shaft rotates about a central axis through a pre-determined angle in an oscillating motion.

The oscillation of the shaft causes the wiper arm to repeatedly sweep across a pre-determined arc on the surface of the screen. Typically, when the wipers are not in use, the wiper arm and wiper blade rest in a stowed position along the bottom edge of the screen. In use, the wiper arm and blade moves from the stowed position and across the surface of the screen, passing through an arc of approximately 90 degrees or more about the central axis of the shaft. Usually, the wiper on the driver's side of the vehicle will move from rest at the bottom edge of the screen, to a point of maximum travel known as the open position, where it is orientated substantially parallel to the perimeter or edge of the screen and the frame that borders the screen.

The area of the screen swept by the windscreen wiper in use does not extend to the perimeter of the windscreen. Instead, the windscreen wiper is designed to maintain a clearance, typically of around 50mm, between the wiper and the frame around the windscreen when the wiper is in the open position. This clearance is to ensure that the wiper does not contact the frame regardless of system tolerances or conditions of use.

The wiper system comprises joints between each key component such as the actuator, the wiper arm, the support structure and the wiper blade. Even small amounts of play between two adjoining components may result in a significant amount of tolerance in the position of the wiper at the full extremes of travel, namely, the stowed and fully open position.

Contact between the wiper and the frame around the screen is undesirable because of the repetitive noise or "slap" caused thereby. Such repetitive noises could serve as an unwanted distraction to the driver and may adversely affect the perceived quality of the vehicle.

In markets prone to high levels of dirt, salt or snow on the roads, the area of the windscreen not swept by the wiper, known as the un-swept zone, may quickly become covered by such contaminants during driving. The deposit of such contaminants on the screen may be so thick as to obscure the affected portion of the screen completely. The obscuration of the un-swept zone adjacent to the substantially vertical portion of the frame surrounding the windscreen, known as the A' pillar, is particularly noticeable to the driver when driving in an urban environment. When the area of windscreen adjacent to the A' pillar becomes obscured, it effectively increases the size of the obscuration zone or blind-spot caused by the windscreen frame, significantly reducing driver visibility in that area.

This can make visibility out of junctions or intersections more difficult.

Over the years, several attempts have been made by vehicle manufacturers to address this problem, leading to a variety of different arrangements for windscreen wipers, utilising expensive and complicated linkage mechanisms. These linkage mechanisms are intended to sweep the wiper arm across the surface of the screen in a manner not possible with a simple oscillating shaft-mounted wiper arm.

However, these linkage mechanisms are not without their drawbacks as they are typically more expensive than the more common systems and require more packaging space, making them unsuitable for some vehicles.

It is against this background that the present invention has been conceived. It is an aim of the present invention to address the issues of packaging and cost and to provide a wiper apparatus with improved wiper performance with increased swept area whilst achieving acceptable sound levels in use.

Aspects and embodiments of the invention may provide a windscreen wiper apparatus for a vehicle arranged to permit an increased swept area by the wiper towards the perimeter of the screen, without unduly increasing the sound levels of the wiper apparatus in use. This approach greatly improves the performance of the windscreen wiper, as reducing the un-swept area of the windscreen improves visibility for the vehicle driver.

Other aims and advantages of the invention will become apparent from the

following description, claims and drawings.

Summary of the invention.

Aspects of the invention therefore provide an apparatus, an arrangement and a vehicle as claimed in the appended claims.

According to another aspect of the present invention there is provided a windscreen wiper apparatus for cleaning a vehicle screen. The apparatus is arranged to move between a stowed position and an open position and comprises: a wiper blade; a support structure for supporting the wiper blade on a wiper arm; and at least one resilient bump-stop, wherein said bump-stop is arranged to limit the excursion of the wiper blade in the open position whilst maintaining contact between the wiper blade and said screen.

Advantageously, the provision of a bump-stop allows the vehicle manufacturer or maintenance personnel to set the open position closer to the frame of the windscreen as the interaction between the bump-stop and the frame limits the excursion of the wiper. In this way, the system tolerances between all the components of the wiper apparatus may be compensated for, at least in part, by the interaction between the bump-stop and the frame around the screen. The provision of a bump-stop arranged to move with the wiper, in use, allows for greater styling freedom in the area around the perimeter of the windscreen and the windscreen frame. This area is particularly critical aerodynamically for features that can increase vehicle drag and cause wind noise which, due to the proximity of this area to the driver, would be particularly noticeable.

In an example, the bump-stop is arranged to move with the wiper blade in use.

In an example, the bump-stop extends beyond the wiper blade to limit excursion in the open position whilst maintaining contact between the wiper blade and the screen.

In an example, the bump-stop is configured to contact a surface adjacent to the periphery of the screen to prevent the wiper blade and/or support structure making direct contact with said surface.

Advantageously, the provision of a surface adjacent to the periphery of the windscreen against which the bump-stop may contact, in use, prescribes a known limit to the excursion of the wiper in the open position and facilitates efficient clearing of the surface of the screen. Additionally, such a surface may be configured to prevent the wiper and/or the contaminants displaced by said wiper to wear against the surface of the windscreen frame, which could otherwise result in damage to the surface of said frame.

In an example, the apparatus further comprises an end-cap arranged to be secured to an end of the wiper blade and, wherein the bump-stop extends from said end cap.

Advantageously, combining the bump-stop feature with an end-cap located at the end of the wiper blade allows for the bump-stop feature to be added to a wiper apparatus only for vehicles intended for markets where such a feature would be particularly desirable. Placing the bump-stop feature at the end of the wiper blade ensures that the trajectory of the bump-stop follows the periphery of the swept area and thus the limit of excursion of the wiper blade in use. Forming the bump-stop feature in the end-cap allows for the bump-stop material to be different from that used to form the wiper-blade, allowing for the materials of the two parts to be optimised for their respective roles. Similarly, separating the bump-stop feature from the wiper blade allows for the wiper blade to manufactured cost effectively by extrusion without the need for additional manufacturing processes or affecting existing production tooling. Additionally, providing the bump-stop feature in the end-cap facilitates retro-fitting of new wiper-blades with the bump-stop feature to older vehicles.

In an example, the bump-stop is mounted to the supporting structure for the wiper blade and extends therefrom.

Advantageously, providing the bump-stop feature on the support structure for the wiper blade minimises the affect of the mass of the bump-stop on the interaction between the wiper blade and the surface of the windscreen. The support structure is more rigid relative to the wiper blade. This allows the tuning of the bump-stop characteristics to be balanced between minimising contact noise in operation and minirnising flexing of the wiper blade at the limit of excursion. Repeated flexing of the wiper blade in cold climates may lead to premature failure of the blade in use.

In an example, the bump-stop is releasably mounted to the wiper arm and extends therefrom.

In an example, the bump-stop is adjustable in at least one dimension, so as to facilitate adjustment of the limit of excursion of the apparatus in the open position.

Advantageously, the provision of a removable and/or adjustable bump-stop feature facilitates retro-fitting of the bump-stop feature to windscreen wipers of older vehicles. The provision of an adjustable bump-stop facilitates adjustment of the position and orientation of the wiper at the limit of excursion in the open position.

In a another aspect of the present invention for which protection is sought, there is provided bump-stop system for an apparatus according to any preceding paragraph, wherein the bump-stop system comprises: a resiliently compliant bump-stop; and a contact portion for engaging the bump-stop to limit the excursion of a windscreen wiper relative to said contact portion.

In an example, the bump-stop system further comprises: a fixing portion arranged to mount the bump-stop to a part of the windscreen wiper apparatus; a contact portion independent from the apparatus arranged to limit the excursion of the apparatus in the open position; and an energy absorbing portion arranged to permit compression of the bump-stop, to maintain contact between the wiper blade and the screen in use.

In an alternative example, the bump-stop system comprises: a fixing portion arranged to mount the bump-stop to a portion of the windscreen frame; and a contact portion formed in the apparatus arranged to limit the excursion of the apparatus in the open position; and an energy absorbing portion arranged to permit compression of the bump-stop, to maintain contact between the wiper blade and the screen in use.

Advantageously, the bump-stop system of the wiper apparatus of the present invention may be employed in one of two configurations, the first configuration has a bump-stop which moves with the wiper, whereas the second configuration has the contact surface moving with the wiper and a bump-stop mounted to the windscreen frame. In this way, the wiper apparatus may be employed with both new and existing vehicle designs without imposing packaging constraints or unduly limiting the styling freedom. The apparatus of the present invention provides the further benefit that the bump-stop system may be arranged to limit the excursion of the wiper apparatus in the open position, whilst the energy absorbing portion permits compression of the bump-stop, minimising the sound produced by the bump-stop when the apparatus reaches the open position.

In an example, the bump-stop comprises: a fixing portion arranged to mount the bump-stop to the windscreen frame; a contact portion distal from the mounting portion arranged to limit the excursion of the wiper blade in the open position; and an energy absorbing portion arranged to permit compression of the bump-stop in-use, minimising the sound produced by the bump-stop when the apparatus reaches the open position in use.

In a further aspect of the present invention for which protection is sought, there is provided a vehicle comprising an apparatus according to any preceding paragraph.

It will also be appreciated by one skilled in the art that the apparatus of the present invention may be suitable for use in other vehicle and non-vehicle based applications.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination thereof. In particular, features described in connection with one embodiment are applicable to the other embodiment, except where there is an incompatibility of features.

Brief Descrirjtion of the Drawincis The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows two views of a known windscreen wiper system on a vehicle, with Figure la showing the windscreen wipers in their stowed position and Figure lb showing the wipers in their deployed or open position; Figure 2 shows the arcuate path taken by the wiper blades and the area of the windscreen the wiper blades sweep in the known wiper system of Figure 1; Figure 3 shows two views of a vehicle with a known wiper system, with Figure 3a illustrating the area of the windscreen not swept by the wipers in use, and Figure 3b showing a more detailed view of the un-swept area adjacent to the perimeter of the windscreen; Figure 4 shows a schematic view of a known wiper system assembly; Figure 5 shows three views of known wiper blade assemblies in detail, with Figure 5a showing the component parts of a typical wiper blade assembly, Figure 5b showing an alternative design of wiper blade assembly also commonly used and Figure 5c showing a detailed perspective view of an end portion of the known wiper blade assembly of Figure 5b; Figure 6a shows a schematic plan view of one embodiment of the windscreen wiper apparatus of the present invention, with Figure 6b showing a section through an end region of the wiper apparatus shown in Figure 6a; Figure 7 shows an above perspective end view of one example of a bump-stop for a windscreen wiper apparatus according to an example of the present invention; and Figure 8 shows an above perspective end view of another example of a bump-stop for a windscreen wiper apparatus according to an example of the present invention.

While the examples given for suitable applications for the present invention relate to windscreen wipers for road vehicles, it will be appreciated by one skilled in the art that there are potentially other uses for the present invention with vehicles not intended for use on public roads and for some non-vehicular applications.

Figures 1 a and 1 b show a front perspective view of a passenger car or vehicle 100 fitted with a known windscreen wiper system 1 operating a pair of wipers. Each wiper comprises an elongate wiper arm 7 supporting at one end a wiper blade 9.

Each wiper arm 7 is mounted to an actuator (not shown) at the end distal from the wiper blade 9. The wiper arm 7 is biased towards a surface of a windscreen 2 so as to keep the wiper blade 9 in contact with the surface of the windscreen in use.

The windscreen 2 is bordered along a top edge by a roof 5 and at the sides by a windscreen frame 3 formed by two roof supports or A' pillars. Along the lower edge of the windscreen 2 is a cowl 4, orientated in a substantially horizontal orientation in the example shown. The cowl 4 is provided with a pair of through-holes or apertures (not shown) through which protrude a pair of wiper actuator shafts 6 (shown in more detail in Figure 4). These shafts 6 are coupled by means of a linkage (not shown) to a suitable actuator (also not shown), such as an electric motor, mounted beneath the cowl 4.

Typically, when the wipers I are not in use, the wiper arm 7 and wiper blade 9 rest in a stowed position is along the bottom edge of the screen 2 as shown in Figure la. In use, the wiper arm 7 and blade 9 move from the stowed position is across the surface of the screen 2, passing through an arc of 90 degrees or more about the central axis of the shaft 6. The point of maximum travel for each wiper arm 7 is known as an open position lo. In the open position lo, each wiper arm 7 is orientated substantially parallel with the perimeter of the screen 2 and the windscreen frame 3 that borders said screen 2.

The component parts of the known windscreen wiper system are shown in more detail in Figures 4 and 5.

Figures 2 and 3 show views of a known vehicle windscreen 2 and windscreen wiper system 100 demonstrating the area of the windscreen 2 swept by the wiper blades 9 and thus kept clear from contaminants such as dirt or snow.

In use, the actuator shaft 6 rotates about a central axis through a pre-determined angle in an oscillating motion. The oscillation of the shaft 6 causes the wiper arm 7 to repeatedly sweep across a pre-determined arc on the surface of the screen 2.

In the example shown in the Figures, the wiper system 100 uses two wiper arms 7 arranged to work together to clear the majority of the surface of the windscreen 2 in use.

The area of the screen swept by the windscreen wipers 1 does not extend to the perimeter of the windscreen 2. Instead, the windscreen wiper 1 is designed to maintain a clearance, typically of around 50mm, between the wiper blade 9 and the windscreen frame 3 around the windscreen 2 when the wiper 1 is in the open position lo. This clearance is to ensure that the wiper 1 does not contact the windscreen frame 3 regardless of component tolerances within the system or conditions of use.

The wiper system 100 comprises joints between each key component such as the actuator, the wiper arm 7, the support structure 8 and the wiper blade 9. Even small amounts of play between two adjoining components may result in a significant amount of tolerance in the position of the wiper at the full extremes of travel, namely, the stowed is and fully open position lo.

The arcuate motion of the wiper arms 7 causes each wiper blade 9 to sweep an area of the surface of the windscreen 2 in the shape of an arc. The wiper arms 7 and corresponding wiper blades 9 are arranged to sweep the windscreen 2 over two overlapping areas or zones. These zones are bounded by an upper boundary 2ub and a lower boundary 2Lb represented by dashed lines in the Figure. The zones are arranged such that one is substantially in-front of the driver and the other is substantially in-front of the front passenger. The area swept by the driver's side wiper blade 9 is shown as 2sd in the Figure. Similarly, the area swept by the passenger's side wiper blade 9 is shown as 2sp.

The swept area 2sd on the driver's side is bounded by a portion of the upper boundary 2ub, shown by a dotted line upper boundary 2d. Both upper boundaries 2ub and 2d terminate adjacent to the windscreen frame 3 at a point prescribed by the position of the wiper blade 9 in the fully open position lo, represented by dashed line 9od. Similarly, the passenger's side swept area 2sp is bounded by an upper boundary 2p prescribed by the passenger's side wiper blade 9 in the fully open position lo, represented by the dashed line 9op. Combining the driver's side swept area 2sd and the passenger's side swept area 2sp results in a combined swept area 2s. The remaining area of the windscreen not swept by the wiper blades 9 in use is known as the un-swept area 2u, as demonstrated in Figure 3a and Figure 3b.

Figure 3b shows clearly the un-swept area 2u left between the driver's side wiper blade 9 in the open position lo and the frame 3 on the driver's side. This area 2u has become opaque due to the deposition of snow or road salt onto the windscreen during driving. Area 2u is particularly noticeable to the driver as it can obscure a significant proportion of the available viewing area of the windscreen.

The perimeter of the viewing area of the windscreen prescribes several viewing angles (not shown). These viewing angles are proscribed by arcs extending from the driver's point of view towards each of the A' pillars or roof frame 3. Significant obscuration of the windscreen 2 around the frame 3 reduces the angle subtended by these arcs, reducing visibility for the driver. A reduction in visibility for the driver in the area around the windscreen frame 3 can make negotiating road junctions more difficult for the driver, as their peripheral vision is impaired by the deposition of contaminants around the sides of the windscreen 2.

In the example shown in the Figures, the vehicle 100 is a left hand drive vehicle. In a left hand drive vehicle, the wiper 1 on the driver's side, which is the left side of the vehicle, is arranged to sweep through an arc from the bottom of the windscreen 2 adjacent to the cowl 4, to a position approximately parallel to the windscreen frame 3. This arrangement leads to an area of the windscreen 2 that is not swept by the wiper blade 9 on the driver's side being kept to a minimum.

The shape of the swept area is optimised for forward visibility for the driver and so, with a right hand drive vehicle, the position of the actuator shafts 6 and the orientation of the wipers 1 is reversed compared to the example shown in the Figures. Such a reversal results in the swept area being optimised for a driver seated on the right hand side of the vehicle. In this way, the driver's side wiper blade 9 is in the fully open position when it is adjacent to and substantially parallel with the frame 3 on the right side of the vehicle 100.

Although not shown in the figures, other arrangements for vehicle wiper systems are also known, where the actuator shafts 6 are each located adjacent to the base of each respective windscreen frame 3. In such an arrangement, the wipers 1 in the stowed position overlie each-other, and in use, move upwards and away from each other. Such an arrangement is often referred to as a clap-hands' wiper system and provides the benefit that there is no need to alter the wiper system to meet the needs of left hand drive or right hand drive markets. However, the clap-hands' wiper systems do leave a large central V' shaped area of the windscreen 2 un-swept by the wipers and have linkage mechanisms which require more packaging volume, which may not be suitable for all vehicles.

Figure 4 shows a schematic view of the main component parts forming a known wiper system assembly shown generally at ii. The wiper system assembly ii comprises an actuator linkage 6a arranged to pivotably support an actuator shaft 6 onto which the wiper arm 7 is mounted. The wiper arm 7 is made up of a lower portion 7L and an upper portion 7u, pivotably joined by a wiper arm pivot 7p. The purpose of the wiper arm pivot 7p is to allow a biasing means 7b, held in tension between the upper and lower portions 7u, 7L of the arm 7, to bias the upper portion 7u of the arm 7 towards the surface of the windscreen 2 in use. A wiper blade assembly 9i is connected to a support structure, generally indicated at 8, mounted to the upper portion 7u of the wiper arm 7, distal from the pivot 7p. The wiper blade support structure 8 comprises a connector portion 8c arranged to releasably connect the wiper blade 9 to the wiper arm 7 50 that it may be replaced when worn.

The wiper blade support structure 8 is arranged to permit relative rotation between the wiper blade 9 and the upper portion 7u of the wiper arm 7 to accommodate any variation in the form of the windscreen surface.

When fitted to a vehicle 100, the actuator linkage 6a and part of the wiper actuator shaft 6 is located below or behind a cowl cover (not shown) and thus is hidden from view. A portion of the wiper actuator shaft 6 protrudes through the cowl 4 and onto this protruding portion is connected the lower portion 7L of the windscreen wiper arm 7.

Figure 5 shows three views of known wiper blades 9 and wiper blade assemblies 9i in isolation from the wiper system assembly ii.

Figure 5a shows an example of a wiper blade assembly 9i of a known configuration. The assembly 9i comprises the wiper blade 9 secured by anchorages 8a to the wiper support structure 8. The wiper support structure 8 in the example shown in Figure 5a takes the form of a resilient, bow-shaped structure formed by a plurality of linkages joined together by pin-joints. This bow-shaped structure is arranged to evenly distribute the biasing force from the wiper arm 7 (not shown) across the length of the wiper blade 9, so as to maintain an even contact pressure between the blade 9 and the windscreen 2. The support structure comprises the connector 8c having a latch 8L with which to releasably connect the wiper blade 9 to the wiper arm 7. The support structure 8 further comprises a pivot point 8p arranged to permit the blade to follow the contours of the windscreen 2 as described previously. To support the entire length of the wiper blade 9 evenly, a reinforcer 9r is provided in a spine-like manner along the top edge of the wiper blade 9.

Figure Sb and Figure Sc show views of another example of a known wiper blade arrangement 1 9i, arranged to perform the same role as the wiper blade assembly 9i of Figure Sa but instead has an integrated reinforcer 19r. In this example, the reinforcer 1 9r takes the form of a resilient, unitary beam-like structure. The purpose of this reinforcer 19r is the same as that of reinforcer 9r in the example shown in Figure Sa, namely to distribute the biasing force evenly from the arm 7 across the entire length of the wiper blade. This type of wiper blade is becoming increasingly popular as it has fewer component parts and, as it does not have the plurality of pin-joints of the bow-shaped support structure, is less prone to freezing or the adverse effects of road salt which can impair the resilience of the wiper blade assembly 9i of Figure 5a.

The wiper blade arrangement 19i comprises a wiper blade 19 formed from a resilient polymeric material such as plastic or rubber in a moulding or extrusion process. The reinforcer 19r is formed integrally with the blade 19 by means of over-moulding or co-extrusion. In this way, the reinforcer 19r formed from a suitable metal or plastics material is not directly exposed to the elements, improving resistance to freezing and the ingress of salt. To seal the ends of the wiper blade 19 and to optimise the support provided by the reinforcer 19r to the wiper blade 19, the blade assembly 19i further comprises an end-cap 19e fitted securely onto each end of the blade 19.

In the case of both of the examples shown in Figures 5a, 5b and 5c, the wiper blade 9, 19 is provided with a number of integrally formed surface features 9f, 19f, configured to optimise wiping performance and improve the flexibility of the blade 9, 19. These features 9f, 19f, ensure the blade 9, 19 conforms effectively to the contours of the windscreen and minimises operating noise in use. A contact edge 9c, 1 9c, arranged to be in contact with the surface of the windscreen 2 is provided along an edge of the blade 9, 19, distal from the reinforcer 9r, 1 9r.

In the example shown in Figures 5b and 5c, the end-cap 19e is arranged to manage the relative movement between the blade 19 and the reinforcer. This ensures that the contact edge 19c is permitted to flex from side to side in a controlled manner in use. This serves to prevent the blade 19 juddering whilst ensuring an even pressure is maintained against the windscreen 2.

Figure 6 shows an example of the windscreen wiper apparatus 20 of the present invention. It is an aim of the present invention to at lease mitigate the size of the un-swept zone 2u and thus improve visibility for the driver.

The present invention has been conceived to reduce the size of the un-swept area 2u by permitting the wiper arm 7 to reliably sweep closer to the windscreen frame 3 than is currently possible with known wiper systems. The present invention allows the wiper blade to sweep closer the perimeter of the windscreen 2 without permitting direct contact between the wiper blade and the windscreen frame 3.

Preventing contact between the windscreen frame 3 and the wiper blade mitigates the risk that the wiper blade might suffer damage or make an unacceptably loud repetitive noise during operation. A windscreen wiper apparatus 20 of the present invention is shown in Figure 6.

Figures 6a and 6b show a windscreen wiper apparatus 20 of the present invention.

The windscreen wiper apparatus 20 comprises a wiper arm 27, connected to a connector 28c provided on a wiper blade assembly 29i. The wiper blade assembly 29i comprises a resilient wiper blade 29, supported by a reinforcer 29r and a plurality of wiper blade reinforcement ribs 29a. The reinforcer 29r is formed by a ridge along the top edge of the blade assembly 29i from a material that is relatively more stiff than the material used to form the wiper blade 29. At either end of the wiper blade 29 in the example shown in the Figure is an end-cap 29e. The end-cap 29e is arranged to control the torsional flexibility of the wiper blade 29 by limiting the relative movement permitted in use between the blade 29 and the reinforcer 29r. The end cap 29e may also serve to seal the ends of the wiper blade 29, preventing ingress of salt or water between the reinforcer 29r and the wiper blade 29.

Figure 6a shows the wiper apparatus 20 against the surface of the windscreen 2, with the wiper blade 29 and wiper arm 27 in the open position 200 adjacent to the windscreen frame 3. In the example shown in the Figures, each end-cap 29e is provided with a bump-stop feature 21 extending from one side of the end-cap 19e towards the windscreen frame 3.

Figure 6b shows a section view B-B cut through an end region of the wiper apparatus 20 of the present invention showing an example of the bump-stop 21 in greater detail. The location of section B-B is shown by a dot-dashed line in Figure 6a. In the example shown in Figure 6a and Figure 6b, the bump-stop 21 extending from the wiper blade assembly 29i is clearly shown adjacent to the reinforcer 29r.

In use, the windscreen wiper apparatus 20 is permitted to move from a stowed position (not shown) to an open position 20o to the extent that the bump-stops 21 are permitted to abut a portion of the windscreen frame 3. In this way, some of the tolerances between the components of the wiper apparatus 20 are compensated for by the action of the bump-stop 21 contacting the windscreen frame 3 and limiting excursion of the wiper apparatus 20 in use.

It will be appreciated that the provision of a bump-stop feature is not limited to being formed by an extension of an end-cap. In an alternative embodiment, not shown, the bump-stop feature is mounted to the side of a wiper support structure by means of a snap-fit connection around the body of the wiper support structure itself. In this way, the benefits of a bump-stop feature may be retro-fitted to existing vehicle wiper systems using the bow-shaped support structure described above and shown in Figure 5a.

Figure 7 and Figure 8 show two alternative bump-stops for the windscreen wiper apparatus of the present invention. Figure 7 shows a bump-stop 121 formed from a compliant closed-cell foam. The bump-stop 121 comprises a relatively stiff ridge portion 121 r which may be arranged to act as an end-cap for a wiper blade or may be configured to snap-fit over a support structure of an existing wiper blade assembly. The bump-stop 121 has a contact region 121c formed from a compliant closed-cell foam. Distal from the ridge portion 121r, the contact region 121c is provided with a contact surface 121s configured to contact a pre-determined portion of the windscreen frame 3 in use. The contact surface 121s is substantially perpendicular to the surface of the windscreen and parallel with the windscreen frame when the wiper is in the fully open position, providing a suitable abutment surface with which to contact the windscreen frame 3. The contact region 121c forms a flange or web extending from the side of the ridge portion 121 r. The extent to which the contact region 121c extends from the ridge portion determines the proximity between the wiper blade and the windscreen frame when the wiper is in the fully open position. As the contact region is formed from a closed-cell foam the bump-stop 121 may be supplied with a relatively large contact region which may be cut to the desired size by the user to optimise the performance of the bump-stop 121 with a particular vehicle.

The bump-stop 121 is formed from a closed-cell foam to ensure that it remains compliant even if used in a cold and wet environment. The closed-cell foam is homogenous in nature and is thus well suited to being used in a variant that may be cut to size without adversely affecting the performance of the bump-stop. It will be appreciated that by optimising the thickness of the contact region 1 21 c and the compliance of the material used, the balance between effectively arresting the wiper in the fully open position and the level of sound generated as the bump-stop contacts the frame may be tuned.

Figure 8 shows another example of a bump-stop 221 for a windscreen wiper apparatus of the present invention. In this example, the bump-stop 221 is formed from a resilient material such as a metal or a plastics material. In this example, the contact region 221c is provided with a void 221v arranged to improve the compliance of the bump-stop 221 in use. The void 221v permits relative plastic deformation of a contact surface 221 s towards a relatively stiffer ridge region 221 r arranged to provide a means of mounting the bump-stop to the wiper blade, wiper blade assembly or wiper arm in use.

The bump-stop 21, 121, 221 of the present invention is intended to make light contact with the windscreen frame 3 each time the wiper reaches the fully open position. If the wiper linkage is incorrectly adjusted, the resulting contact with the frame by the bump-stop will result in the wiper blade being lifted off the surface of the windscreen whenever the wiper reaches the fully open position. Such a condition is undesirable as it tends to cause increased wind noise between the blade and the windscreen and can cause the blade to judder at the beginning of the return stroke as it moves towards the stowed position. Juddering of the wiper blade against the surface of the windscreen is detrimental to wiper performance, causing smearing of the windscreen and increasing the wear on the wiper blade.

The compliance of the bump-stop of the present invention absorbs at least some of the contact between the wiper and the frame when the wiper reaches the fully open position. This compliance ensures that the wiper blade remains in contact with the surface of the windscreen at all times. Additionally, the compliance permits the wiper and wiper linkage to be adjusted to move the blade closer to the frame when in the fully open position, managing the mechanical tolerances in the linkage by the contact between the bump-stop and the frame.

It will be appreciated that the extent to which the contact surface 121s, 221s is positioned away from the wiper blade will determine the width of the un-swept area between the wiper blade and the windscreen frame. In order to obtain the maximum benefit in swept area of the windscreen, the contact region 121c, 221c must be less than the clearance gap usually provided between the wiper and the frame. If the bump-stop of the present invention is to be used in a windscreen wiper system as part of a retro-fit, the wiper linkage must be adjusted accordingly, ensuring the bump-stop contacts the frame whenever the wiper is in the fully open position.

It will be appreciated that the bump-stop as described above and shown in the Figures may be adapted to be secured to the windscreen frame itself and arranged to make contact with the wiper blade, support structure of wiper arm as desired. It is envisaged that the bump-stop of the present invention may be supplied to the user as an after market kit of parts. The kit could comprise at least one bump-stop as previously described above and a contact patch (not shown). The purpose of the contact patch is to cover the portion of the frame that would otherwise be contacted by the bump-stop in use. The contact patch may comprise a clip-on structure or self adhesive backing that may be applied directly onto the frame surrounding the windscreen and would be formed from a suitable resilient material to protect the paintwork of the frame.

It will be apparent to one skilled in the art, that the wiper apparatus of the present invention may be employed on any wiper system arranged to move a wiper blade in an oscillating manner across any transparent member of a vehicle. Examples of suitable applications for the present invention include: the front windscreen; the rear window of a vehicle; headlamp wash/wipe systems; and wipers for side windows as may be used in utility vehicles.

Other advantages will be apparent to one skilled in the art and the present examples and embodiments are to be considered illustrative and not restrictive.

The invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

Claims (12)

1. CLAIMS1. An apparatus for limiting the movement of a vehicle windscreen wiper movable between stowed and open positions, the apparatus comprising: bump-stop means mountable to at least a part of the windscreen wiper and arranged to contact a portion of a frame of the windscreen so as to limit the excursion of the wiper blade in the open position.
2. 2. An apparatus as claimed in claim 1, wherein the apparatus is arranged to move with the windscreen wiper in use.
3. 3. An apparatus as claimed in claim 1 or claim 2, wherein the bump-stop means extends from the windscreen wiper so as to contact the frame whilst maintaining contact between the windscreen wiper and the screen.
4. 4. An apparatus as claimed in any preceding claim, wherein the bump-stop means is arranged to contact said frame so as to prevent a wiper blade and/or support structure of the windscreen wiper from making direct contact with said frame.
5. 5. An apparatus as claimed in any preceding claim, comprising mounting means for mounting the bump-stop means to a wiper blade and/or support structure of the windscreen wiper.
6. 6. An apparatus as claimed in claim 5, wherein the mounting means comprises an end cap adapted to be secured to an end of the wiper blade and/or support structure, wherein the bump-stop means extends from the end cap.
7. 7. An apparatus as claimed in any preceding claim, wherein the bump-stop means is releasably mounted to a wiper blade or wiper arm of the windscreen wiper.
8. 8. An apparatus as claimed in any preceding claim, wherein the bump-stop means is arranged to extend from a wiper blade or wiper arm of the windscreen wiper in a direction generally perpendicular thereto and/or substantially tangential to the direction of movement of the windscreen wiper.
9. 9. An apparatus according to any preceding claim, wherein the bump-stop means is adjustable in at least one dimension, so as to facilitate adjustment of the limit of excursion of the wind screen wiper in the open position.
10. 10. An apparatus as claimed in any preceding claim, wherein the bump-stop means is flexible, compressible and/or resilient.
11. 11. A windscreen wiper arrangement for a vehicle having at least one windscreen wiper comprising an apparatus as claimed in any preceding claim.
12. 12. A vehicle comprising an apparatus according to any preceding claim.