Windshield wiper blade and a wiping strip for such a blade

The invention is concerned mainly with a wiping strip for a windshield wiper blade, the strip comprising a base and a wiping element for wiping contact with a surface. The wiping element is articulated on the base through a web portion which is protected from deposits of mud, ice etc. by two wing portion which also improve the aerodynamic performance of the wiping strip. The invention is particularly applicable to equipment for automotive vehicles.

FIELD OF THE INVENTION 
This invention relates to windshield wiper blades, and to flexible wiping 
strips for such blades. It is particularly applicable in connection with 
the wiping of glasses or windshields, especially in automotive vehicles. 
BACKGROUND OF THE INVENTION 
In the prior art, windshield wipers have been made that include a blade 
which is moved over the surface to be swept, for example a windshield, 
under the action of a motor. Such windshield wipers include at least one 
oscillating arm which carries a blade that includes a wiping strip. The 
wiping strip generally comprises a base and a scraping or wiping element. 
The wiping strip is carried by the blade which is articulated on the arm, 
with the latter applying the blade firmly against the swept surface while 
moving it in an oscillating movement. 
In order to overcome problems of mechanical behaviour, for example 
noisiness, it is known to articulate the base on the wiping element itself 
by interposing a web between these two portions of the wiping strip. Such 
a web may be defined by one or more cavities formed along the wiping 
strip. 
Such arrangements have deceptive aerodynamic behaviour, in particular at 
high speeds. Under the effect of eddies of air, lateral overpressures tend 
to occur, which cause the wiping strip to undergo a constraint which tends 
to oppose the required angular deformation about the web. 
In addition, such an overpressure can induce a braking effect in the 
movements of the windshield wiper blade: this needs to be avoided, for 
example under high-stress driving conditions in a high speed vehicle. 
Another problem has become apparent under certain wiping conditions. Thus, 
when the blade sweeps the surface of the windshield, it often happens that 
the region around the web can become clogged by accumulations of foreign 
matter, for example, ice or mud comprising a mixture of dust and water. 
This reduces the ability of the strip to flex at the web, which is 
damaging both to performance and to the structure of the strip. In 
addition, such accumulations of matter can be transferred onto the 
windshield. 
In French patent No. 1 250 889, a wiping strip has been proposed which is 
protected from the surrounding air, since it is disposed within a mask in 
the form of a channel or gutter carried by the windshield wiper arm 
itself. The main drawback of that arrangement is that ingress of dust and 
accumulation of ice during snowfall are not in fact prevented, for example 
between the channel and the wiping strip itself. It is therefore possible 
to reach a point at which the channel is full of dust and ice and the 
wiping strip is therefore unable to function properly. In addition, the 
channel is a supplementary component of a windshield wiper, which adds to 
the cost of the wiper assembly. 
In the solution of another problem that has been proposed in the prior art, 
it is known to arrange for the wiping strip to be stiffened in such a way 
that the windshield wiper remains permanently in contact over its whole 
length with the swept surface. With this in view, the upper part of the 
base, i.e. the part opposite the web, is formed with a recess or cavity in 
which a vertebra or stiffener can be fitted. This arrangement increases 
the risks of braking of the windshield wiper blade and, more particularly, 
of clogging by mud or ice. 
DISCUSSION OF THE INVENTION 
An object of the present invention is to provide a remedy for the drawbacks 
of prior art arrangements mentioned above, and to improve the performance 
of windshield wiper and similar wiping systems, the invention being 
directed to a windshield wiper wiping strip of the kind comprising a base 
and a wiping element which are joined to each other through a web portion. 
The invention is mainly characterised in that the wiping element includes 
two wing portions which are arranged on either side of its greatest cross 
sectional dimension and which are arranged so as to mask cavities provided 
on the wiper blade, in particular during displacements of the blade, in 
such a way as to protect the said cavities against variations in pressure 
of aerodynamic origin, and against accumulations of matter such as ice or 
dust. 
The invention also embraces a windshield wiper blade which is equipped with 
such a wiping strip. 
Further features and advantages of the present invention will be better 
understood from the following description, given by way of example and 
with reference to the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
In FIG. 1, a wiper blade in the said first embodiment has as its main 
features a base 1 and a wiping element 8, which is articulated on a base 1 
through a web portion 5. As thus described, such an arrangement is 
conventional. Two longitudinal cavities 2 are provided in the base 1, 
defining between them a central spine portion 3. The cavities 2 are formed 
between the upper or terminal portion of the base 1 and a body portion 4 
of the base, with the web portion 5 projecting from the body portion 4. 
The purpose of the cavities 2 is to receive a stiffening rib (not shown), 
which is also referred to as a vertebra and which enables the transverse 
configuration of the wiper blade to be improved. 
The wiping element 8 is formed with two wing portions 6a, 6b, on either 
side. The wiping element 8 engages the swept surface S, which is indicated 
in FIG. 1 by a phantom line. The windshield wiper blade is symmetrical 
about a central plane indicated at 9 in FIG. 1, along which the greatest 
cross sectional dimension of the wiping strip is measurable. When the 
blade is stationary the surface S is perpendicular to the plane 9. The 
wing portions 6a and 6b extend outwardly and in the longitudinal direction 
of the plane 9 away from the wiping element 8, in such a way as to be 
capable of masking body cavities, 14a and 14b, in a direction 
substantially perpendicular to plane 9. Said cavities being defined 
between the wing portions, the web portion 5 and the body portion 4 of the 
base. 
Each of the wing portion 6a, 6b has an inner or upper surface or face 
facing towards the base 1, and an outer or lower surface of face facing 
away from it. 
It will be appreciated that currents or eddies of air 13 are guided by the 
curvature 15 of the outer face of the wing portion 6a or 6b. In order to 
improve the dynamic behaviour of the wiper blade during a wiping movement, 
the outer faces of the wing portions are formed with aerodynamic profiles. 
In one embodiment, the outer face of each wing portion is concave outwards, 
being in the form of a portion of a cylinder, the centre of curvature of 
which is disposed on the same side of the wing portion as the swept 
surface S. A typical value for this radius of curvature is 11.5 cm. Such a 
wing profile is beneficial to the aerodynamic performance of the wiper 
blade during operation on the swept surfaces. 
It will also be understood that the length of the wing portions is such 
that the cavities 14a and 14b are permanently masked in a direction 
substantially perpendicular to said plane 9, as shown in FIG. 1, 
regardless of the angle through which the web portion 5 is deflected. In 
this way the greater part of the risk of the cavities 14a and 14b being 
filled with deposits of ice, dust or snow is avoided. 
The angular deflection of the web portion 5 can be limited to a 
predetermined value by suitable design of the profile of the wing portions 
6a and 6b. Thus, during angular deflection, the inner face 12 of one of 
the wing portions comes into contact, as indicated in broken lines at 11, 
with the body portion 4 of the base 1, to define a fully deflected 
position indicated in broken lines at 10, so that further angular 
deformation of the wiper blade about its web portion 5 is elastically 
prevented. 
In order to avoid friction noise and other parasitic effects, the profile 
of the inner faces of the wing portions 6a and 6b is chosen to be such 
that the possible contact area between these inner surfaces and the body 
portion 4 of the base 1 will be reduced to a minimum. 
In another embodiment, which is shown in FIG. 2, a stiffener 16 is 
installed at the outer end of the base 1 in the cavities 17 which 
correspond substantially to the cavities 2 in FIG. 1. The wing portions 18 
extend past and beyond the cavities 17, as shown, in such a way that they 
guarantee good protection for the whole of the wiper blade. 
The web portion 19 extends from a frustoconical portion 20 of the base 1, 
to define a groove which enables air flow to be controlled. During angular 
deflection of the web portion 19, the inner surface of the wing portion 18 
comes into engagement against a shoulder 23 defined at the outer end of 
the frustoconical portion 20. 
In a preferred embodiment, cavities 22, in the form of longitudinal 
grooves, are provided at the level of the web portion 19 and on either 
side of the latter. These cavities are formed on each side of the wiper 
blade and are continuous with the cavities 14a and 14b already described; 
the lower or inner surface 24 of each cavity 22 is an extension of the 
inner surface of the corresponding wing portion 18. The frustoconical 
portion 20 is extended at the level of the web portion by a radially 
extending inner terminal cavity portion defined by a wall 21. 
The frustoconical portion 20 of the base has an inclination such that the 
contact area between the base and the wing portion 18 during angular 
deformation is reduced to a minimum. This inclination may be made 
variable, if desired, by making this part of the base with a curved 
surface. 
Again in a preferred embodiment, and as is shown in the drawing, the angle 
made between each wing portion 18 and the central plane 9 (FIG. 1) is 
about 47.degree., the wing portions being symmetrical about the greatest 
dimension of the wiper blade cross section, i.e. that in the plane 9. The 
frustoconical portion 20 of the base is itself arranged symmetrically on 
an apex half-angle of 40.degree., the value of this angle being smaller 
than the angle between each wing portion and the plane 9. 
The wiper blade may be made by extrusion in synthetic rubber. 
The invention is of course not limited to the particular embodiments 
described above, but embraces any embodiment within the scope of the 
invention.