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This invention concerns the manufacture of windscreen-wiper blades for
motor vehicles. Obviously, numerous solutions have already been proposed
with a view to ensuring maximum efficiency despite the sometimes
considerable variations in the radius of curvature of the surfaces to be
cleaned.
Seeking that efficiency has often caused other important aspects of this
manufacture to be overlooked. More particularly, the purpose of the
invention is not only to increase the efficiency of the windscreen-wiper
blade by reason of the number of points of application of the frame on the
squeegee but also, as regards manufacture, to attain maximum
simplification and standardization, especially in the composition of
different blade models. By the present invention it is possible, with one
sole type of large bridge and one sole type of small bridge or bar, to
ensure the construction of windscreen-wiper blades with a length varying
from the value of two lengths of the small bridge to the maximum value
given by the extreme axial position, including intermediaries.
These aims are attained by the fact that, according to the invention, the
windscreen-wiper blade of the type composed substantially of a large
bridge on each end of which is articulated a bar or small bridge, is
characterized by the fact that contact between the said bar and the
elastic strip is ensured by means of a plurality of pressure zones.
The said bars or small ridges are generally elastic. The relatively rigid
large bridge and the relatively elastic bars or small bridges are mutually
articulated, either by the oscillation axes or by means of an elastic
bond.
These new characteristics can be employed in very different forms, by
modifying the morphology and dimensions of the constituent parts. Also by
choosing different materials suitable both for the relatively rigid large
bridge and for the elastic bars or small bridges. The bonding means
between the different pressure zones or points of the bars and the elastic
scraping strip can also vary.
As an example, implementations are described in more detail below, without
a restrictive nature, and referring to the appended drawings in which:
FIG. 1 represents schematically the distribution of thrust effects on the
elastic strip in a conventional windscreen-wiper blade;
FIG. 2 represents schematically the position of thrust effects on the
elastic strip in a windscreen-wiper blade according to the invention;
FIG. 3 is an exploded view of the constituent parts of a windscreen-wiper
blade frame according to the invention;
FIG. 4 represents, assembled, a windscreen-wiper blade applying the
elements of FIG. 3;
FIG. 5 represents a windscreen-wiper blade according to the invention
applied against a surface to be cleaned;
FIG. 6 represents a front view of part of a rectilinear windscreen-wiper
blade according to the invention;
FIG. 7 is similar to FIG. 6 and refers to a curved windscreen-wiper blade;
FIG. 8 represents a front view of a variant of FIG. 6;
FIG. 9 is similar to FIG. 8 but refers to a curved windscreen-wiper blade;
FIG. 10 represents a front view of a second variant of the implementation
in FIG. 6;
FIG. 11 is similar to FIG. 10 but refers to a curved windscreen-wiper
blade;
FIGS. 12 to 20 schematize briefly different possible implementations of the
windscreen-wiper blade according to the invention;
FIG. 21 represents a front view of a practical execution in one sole piece;
FIG. 22 is a plane view of it;
FIGS. 23 and 24 represent, respectively, a section along lines XXIII--XXIII
and XXIV--XXIV of FIG. 21.
As schematized in FIG. 1, in conventional windscreen-wiper blades where the
bearing surfaces between the frame and the elastic strips are ensured by
point or linear contacts, the pressure effort distribution is such that
the attraction stresses of the elastic strip are extremely variable in
each section delimited by successive bearing surfaces. On the contrary, as
shown in FIG. 2, the windscreen-wiper blade device according to the
invention ensures an appreciably more regular distribution over the whole
length of the elastic strip.
A large or primary bridge member 1 on both ends of which is articulated a
bar or small or secondary bridge member, respectively 2-3, is represented
symbolically in the two schematic representations of FIGS. 1 and 2. In the
FIG. 1 example, the localized contacts between the said bars 2-3 and the
elastic strip schematized in 4 are effected with the intervention of
extremely small surfaces. In the schematic representation of FIG. 2, the
bars or little bridges 2-3 rest on the elastic strip schematized in 4 in
such a way that contact is effected by the intermediary of zones 5.
It is thus possible to distribute the thrust effect over the whole length
of the elastic strip 4 which is represented by the FIG. 2 diagram.
In the pressure zones, the number of contact surfaces is variable.
In the execution of FIGS. 3, 4 and 5, the windscreen-wiper blade-holder
according to the invention is constituted by a large, rigid bridge 1 on
each end of which is articulated an elastic or flexible bar or small
bridge, respectively 2-3. These rest on the elastic strip 4 which is
strengthened in a known manner by one or more metal bands 6, with the
intervention of a plurality of pressure zones or points, respectively 7 to
11 and 12 to 16. The said small bridges or bars 2-3, in the rest position,
are slightly curved so that, in this position, the elastic strip 4
delimits a concave curve, to which end the said pressure zones or points 7
to 16 are spread out along a curve a-b-c which will generally be different
from the curve of the surface to be wiped S. In this same implementation,
the small bridges or bars 2-3 present, about in their middle, a plurality
of holes, respectively 17 to 20 and 21 to 24.
By adequate combination of the large bridge 1 and the small bridges or arms
2-3, the range of the two-bar unit can be varied so as to obtain a length
varying from the value of two lengths of a small bridge or bar to the
maximum value corresponding to the extreme axial position.
It will be observed that in this windscreen-wiper blade, despite the
numerous variants that are possible in regard to the relative position of
the pressure zones or poins 7 to 16, only two different parts are used,
conforming respectively to the large bridge 1 and the small bridges or
bars 2-3 which are identical.
The large bridge 1 will generally be made of metal so as to possess good
rigidity, whereas the small bridges or bars 2-3 will be made of a
relatively elastic or flexible matter, either of spring steel or a
synthetic material.
If the large bridge is made of plastic, the chosen substance must possess
more rigidity than that used to make the small bridges or bars 2-3.
In the implementation in FIGS. 6 and 7, the bar 2 has been cast in one sole
piece with the large bridge 1. In the junction zone 25, the thickness of
the matter may be reduced so as to obtain good elasticity or flexibility
in the joint thus made.
FIGS. 8 and 9 show implementations similar to those in FIGS. 6 and 7, but
the joint between bar 2 and large bridge 1 is effected in the conventional
manner by a pivoting pin 26.
The implementations represented in FIGS. 10 and 11 show the large bridge 1,
the bars 2 and, connected to both ends of the said bars, a multiple
bearing zone element, respectively 27-28.
These elements consist of small plates with lateral tongues 29 by means of
which a plurality of extremely effective pressure zones are delimited.
These small plates should preferably come from the works with the bars or
small bridges.
As an indication, in FIGS. 12 to 20 numerous different combinations are
represented in which are systematically found one large bridge 30, small
bridges or bars 31 and pressure zones 32; all these implementations can
apply one or more of the characteristic arrangements described above.
In the implementation shown in FIGS. 21 to 24, the large bridge 33 and the
small bridges or bars 34-35 are made in one sole piece, generally of
plastic. In this implementation, the two branches 33' and 33" of the large
bridge are of unequal length; similarly the sections 34'-34" and 35'-35"
of the small bridges, respectively 34 and 35, are of unequal length. In
the event, the longer sections, respectively 34" and 35" are directed
towards each other, i.e. towards the inside of the device.
It goes without saying, of course, that the number of pressure zones or
points is variable.
Naturally, various modifications can be made by a craftsman to the devices
or processes which have just been described as non-limitative examples,
without going beyond the scope of the invention.
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