Note: Descriptions are shown in the official language in which they were submitted.
CA 02583885 2007-04-04
TITLE: Automotive Wiper Assembly
FIELD OF THE INVENTION
This invention relates to wiper blades for reinoving water from the
windshields
of vehicles. More particularly, it addresses a wiper blade assembly designed
to
accommodate a high-speed airflow over a vehicle windscreen.
BACKGROUND TO THE INVENTION
An automotive windshield wiper removes water from a car windshield. It is
operated by a wiper motor and mechanical linkages that move a wiper ann back
and
forth in a predetermined arc. At its end, the wiper ann carries a wiper blade.
Along
part of the arc, when the wiper blade is elevated and generally in line with
the
direction of airflow passing over the windshield, the airflow has a reduced
tendency
to lift the blade off of the windshield. Along another part of the arc, when
the wiper
blade is near even to the horizontal plane, the airflow has a greater tendency
to lift
the wiper blade off of the windshield. This effect, particularly at high
speeds, can
reduce the effectiveness of the wiper blade in removing water from the
windshield.
Conventional detachable wiper blades are secured to mechanically actuated
wiper anns at the end of the wiper ann. The free end of the wiper arm may be
provided with a transverse pin or a hook for engagement with the blade or with
a
connector that, in turn, engages with the blade or a blade assembly.
Some blade assemblies include a skeletal frame that carries the wiper blade.
When a skeletal frame is employed as part of the blade assembly, it often
includes a
first arcuate link of a length that is approximately half the length of the r-
ubber blade,
and two shorter, secondary links carried at the respective ends of the first
arcuate
link. The ends of the two shorter links are connected at four locations to the
flat
stiffener that is inter-fitted with the rubber blade, distributing the force
being applied
to the blade. All of these links in a skeletal frame are generally
approximately
symmetrically arranged with respect to the length of the rubber blade and the
longer,
first, arcuate link is fitted to the end of the wiper arm at its center point
with the
object of balancing the distributed force supplied by the wiper ann to the
rubber
blade. Other skeletal fonns may be employed as well. Such frames, as well as
connectors that directly engage the end of the wiper ann, generally connect to
the
stiffener that is coupled to the rubber blade
With or without the presence of a skeletal frame, the blade portion of a
standard wiper, generally made of rubber, has mounted into it a flat, two-
dimensional
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CA 02583885 2007-04-04
strip stiffener, generally made of steel. The stiffener and wiper blade have
complementary slots that allow them to inter-fit with each other. The
stiffener is
fitted into lateral groove-like slots fonned along the sides of the body of
the wiper
blade. The central spine of the rubber blade is fitted into a centrally placed
slot
extending down the length of the stiffener.
The stiffener is substantially rigid in the directions lateral to its
longitudinal
extent and parallel to the surface of the windshield. But in a plane upright
to the
windshield, the stiffener is generally soft enough to comply with the window-
directed force applied by the wiper ann, but stiff enough to distribute this
force along
the blade. The stiffener is substantially constrained by its aspect ratio to
bend
preferably within a plane having a surface which coincides with a
perpendicular
extending outwardly from the upper and lower surfaces of the stiffener.
Hereafter,
this is referred to as the "bending plane of the stiffener".
In the absence of a skeletal frame, a blade may be attached directly to the
end
of the wiper arm by connection to the sides of the stiffener or so connected
through a
connector. Such a latter wiper configuration may be characterized as a "beam"
blade,
cf US patent 6,654,984.
The stiffener, in almost all blades as well as in a beain blade, is typically
made
of steel, and can function as a leaf spring. Such a flexible strip, when
functioning as
a spring, may be formed to assume a natural curvature when free of any
external
applied force. A specific curvature may be induced to improve the uniformity
of the
force with which the rubber blade is applied to a windshield. This is
particularly
appropriate when the windshield may have a degree of curvature but is also
relevant
to obtain a preferred, generally even distribution of the pressing force of
the blade
along the full length of blade. The source of the applied force is the wiper
ann, which
is generally spring-loaded to press the wiper blade against the windshield.
The present invention is adaptable to incorporation with either type of blade
assembly mounting system.
It has been known, in order to reduce the tendency of a wiper blade to lift-
off or
shudder under the influence of a high velocity wind stream, to provide such
blades,
or their corresponding blade assemblies, with airfoils. Examples of airfoils
on a blade
support assembly include US patents 2,799,887; 5,319,826; 5,946,764 and
6,523,217.
Such airfoils use the force of the wind stream to increase the tendency of the
wiper
blade to press against the windshield. This effect is particularly appropriate
when the
wiper blade is in a more nearly horizontal orientation. Such airfoils have
been
deployed both as part of the blade assembly holding a rubber blade and on the
rubber
blade itself.
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Blades intended to have an airfoil effect have included configurations where
the upper body is triangular in cross-sectional form. Some designs have had an
upper blade body with the cross-section of an equilateral triangle, cf US
patent
3,418,679, and US published application US2007/0022556 Al. Other designs have
had the cross-section of an isosceles triangle, cf US 6,499,181; 6,516,491;
6,836,924;
6,874,195 and German patent DE10007808 (2001). In both cases, a more upright,
inclined top face of the body of the blade is presented to the wind stream
than where
the blade body is rectangular in cross-section. Such an inclined top face
functions as
an airfoil to increase the pressure applying the blade to the windshield.
In German patent publication DE 198 54 372 Al the body of the wiper blade
above the stiffener is angled to present its leading side face to the wind
stream at an
inclined angle, similarly serving the function of an airfoil. The "crooked"
orientation
that this presents for coupling to the wiper arm is compensated for by a twist
in the
wiper arm itself.
The stiffeners in blades have also been enlarged to provide both symmetrical
and asymmetrical extensions on either side of the length of a blade that
provide an
airfoil effect, cf US patents 6,516,491 and 6,675,433. Cases have even
occurred
where the stiffener itself, or portions thereof, have been inclined with
respect to the
wiper blade, cf US patent 3,037,233 and German patent DE10107021.
Traditionally, in the past, a rubber wiper blade has been constructed with a
wiping edge that is supported by a widening strip of rubber having the general
shape
of an arrowhead in cross-section. This arrowhead cross-section is, in turn,
coupled to
the main body of the wiper blade through a long narrow strip of rubber that
functions
as a "neck". As the wiper blade is moved back and forth, the arrowhead cross-
section portion, flexes about the neck dragging the wiping edge across the
windscreen at a preferred angle of inclination suitable to remove moisture.
This may
be described as blade edge "deflection" arising from a wiping action.
A degree of deflection of this type is desirable to minimize shuddering of the
blade. The relative width of the neck and arrowhead portions focuses
deflection
primarily at the neck. The upper, wider portion of the arrowhead on deflection
of the
arrowhead limits the degree of deflection by contacting the underside surface
of the
main body of the blade to which the neck is connected.
As mentioned previously, the wiper ann is spring-loaded to direct the free,
distal, end of the wiper arm towards the windshield. When a wiper blade
incorporating a stiffener, with or without a blade support assembly, is fitted
to the
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end of the wiper ann, the wiper arm applies a pressing force which is
transmitted
through to the wiper blade, urging the wiper blade to press against the
windscreen.
Generally, the connection between the wiper blade and the end of the wiper
ann is made approximately around the center region of the length of the wiper
blade.
This contributes to a relatively balanced distribution of the pressing force
along the
length of the wiper blade. This same connection can apply the pressing force
to the
wiper blade, if so arranged, in a direction that is offset from the wiper edge
of the
blade so as to generate a torque that tends to rotate the wiper blade about
its
longitudinal axis, cf Gennan patent DE2627832 and Japanese patent JP 7179165.
This torque is resisted by the coupling between the blade and the end of the
wiper
arm, which may be relatively stiff. Consequently, the greater part of the
response to
this torque occurs within the rubber wiper blade itself.
Before contacting a windshield, the arrowhead portion of the wiping edge is
generally presented to a windshield in an upright, near-perpendicular
orientation.
The arrowhead cross-section portion of the blade will tend to bend about the
neck as
the blade edge is wiped across the windshield, with the blade edge trailing.
By
minimizing the presence of any torque arising from the pressing force, the
tendency
to develop blade edge deflection significantly beyond the limit arising from
contact
between the arrowhead and blade body portion can be held to similar values
irrespective whether the blade edge is being wiped in a first or second,
reverse
direction.
As indicated earlier, blade support assemblies, or in the case of a beam
blade,
the blade with stiffener are typically coupled to the end of the wiper arm
through a
connector. Such connectors may have a variety of shapes to adapt the
installation of
a wiper to the range of wiper arms included on vehicles made by different
manufacturers.
Connectors have also been articulated to allow wiper blades to rotate not only
about an axis that is transverse to its longitudinal length, but also to
provide freedom
for a blade to swivel sideways, about an axis parallel to such longitudinal
length, cf
US patents 2,942,288; 3,431,579, and 3,751,754. Further, connectors have been
offset or angled so as to shift the position of the wiping edge laterally from
alignment
with the center of force applied by the end of the wiper arm, cf Japanese
patent
JP7179165.
In cases where connectors have been offset at an angle, provision has been
made to ensure that the blade is mounted at an orientation that presents the
wiping
edge to the windshield in an upright orientation. This contributes to allowing
the
blade to have more nearly balanced deflections of the blade edge as it
reciprocates in
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either lateral direction. In this latter case as well as other cases, the
mounting of
wiper blades has been arranged to direct the line of force applied by the end
of the
wiper arm to a location which is laterally displaced from the line of wiping
edge.
Other prior art references of possible interest include US patent 3,089,174
and
US publication US2003/0138655 Al.
It would be desirable to provide a wiper blade that has a configuration that
advantageously resists the action of a wind stream in lifting the blade off a
windshield at high speeds. At the same time, the wiper blade should be easy to
fabricate and readily adaptable to existing wiper blade installation systems.
The invention in its general form will first be described, and then its
implementation in terms of specific embodiments will be detailed with
reference to
the drawings following hereafter. These einbodiments are intended to
demonstrate
the principle of the invention, and the manner of its implementation. The
invention
in its broadest and more specific fonns will then be further described, and
defined, in
each of the individual claims which conclude this Specification.
SUMMARY OF THE INVENTION
The present invention, according to one aspect, addresses a wiper blade with
and apart from a wiper assembly for a vehicle that is adapted to improve the
tendency for the wiping edge of the rubber blade to press against a vehicular
windshield and remove moisture accumulated thereon in the presence of a wind
stream flowing over the vehicular windshield.
In order to provide a supplemental pressure directing the wiper blade against
the windshield in the presence of a wind stream, the wiper blade is adapted to
function as an airfoil or air dam. The resulting airfoil effect enhances the
force with
which the wiper blade is pressed against the windshield in the presence of
higher
velocity wind streams. Alternately or concurrently a portion of the wiper
blade
assembly restricts the extent to which airflow is applied to the lower portion
of the
blade, thus reducing the tendency for lift-off to occur.
The invention applies to a flexible wiper blade having a longitudinally
extending upper body and a lower, longitudinally extending wiping edge. The
wiping edge is supported as part of the blade by a longitudinally extending
edge
support portion, generally and preferably having the shape of an arrowhead in
its
cross-section.
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The edge support portion is connected to the body by a longitudinally
extending neck. A central geometric plane for the wiping edge portion of the
wiper
blade may be defined as a plane running the length of the blade, which
includes both
the wiping edge, and the neck portions of the wiper blade when the blade is
extended
in a straight line without being pressed against a windshield surface. Over a
short
interval, such a plane also can also be effectively defined in the center
portion of a
curved blade.
A longitudinally extending stiffener stiffens the flexible wiper blade. The
stiffener can be fitted to the blade in a variety of manners. According to one
aspect
of the invention, the body portion of the wiper blade has a pair of lateral
mounting
slots to receive a generally flat, longitudinally extending stiffener. The
mounting
slots generally run longitudinally for the length of the main body, along the
length of
the sides of the wiper blade, and therefore are laterally positioned on the
wiper blade.
The stiffener, according to a preferred variant of the invention, has a
central,
longitudinal, stiffener slot divided into two portions separated by a central
bridge
joining the two sides of the stiffener. The width of these two stiffener slot
portions
corresponds to the width of a corresponding, interrupted, "spine" running the
length
of the rubber blade. This spine within the rubber blade constitutes the
separation
between the two lateral mounting slots in the blade. The spine of the blade is
fitted
into the two longitudinal slot portions on the stiffener. The spine is topped
by a
longitudinal capping strip, divided into two portions, that extends along the
top of the
rubber blade. The sides of these two capping strips overlie the adjacent
surfaces of
the stiffener on both sides of the stiffener slot when the blade and stiffener
are
interengaged, anchoring the parts together.
The respective stiffener slots each has a short widening that will admit a
respective portion of the two capping strips to pass there through, allowing
the spine
to be slid into place within the stiffener slot for the entire length of the
blade.
The stiffener, when mounted engaged with the lateral slots on the wiper blade,
is of a width that causes portions of the stiffener to extend outwardly from
the sides
of the body portion of the wiper blade, or at least on one side. Conveniently,
the
sides of the stiffener serve as coupling means in mounting the blade to a
wiper arm as
will be shown in more detail subsequently below. Additionally, the one or more
outward extending sides of the stiffener provide surfaces which are useful for
functioning as an airfoil or air dam.
It is a feature of the invention that the stiffener is mounted to the blade at
an
inclined angle. In a preferred embodiment the mounting slots on the blade are
inclined at an offset angle from the central geometric plane for the wiping
edge by an
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angle, an "offset" angle. That is, the angle between the bending plane of the
stiffener
and the central plane of the wiping edge constitutes the "offset angle".
The top of the capping strip of the wiper blade, when the stiffener is mounted
interengaged with the blade body, is also preferably, but not necessarily,
slanted in a
similar manner, preferably by the same offset angle from the central plane of
the
wiping edge.
By providing for one or more of the sides of the stiffener to extend outwardly
from the sides of the body portion of the wiper blade, the offset angle of the
mounting slots causes the face surfaces of such extending side portions, (as
well as
the top of the capping strip of the wiper blade), to be presented, when
mounted on the
windshield of a car, so that protruding face surfaces are more nearly oriented
towards
the direction of the travel of the vehicle. In this configuration, such face
surfaces (as
well as the top of the body portion of the wiper blade) provide the function
of an
airfoil or an air dam.
By reason of the angled orientation of the stiffener, its lower, leading, edge
is
positioned relatively close to, and preferably evenly spaced from, the surface
of the
windshield when a wiper according to the invention is installed on a vehicle.
This
close proximity arises from the inclination of the stiffener. The lower front
edge of
the single blade is thereby positioned more closely to the windshield,
reducing the
space for the wind stream to get beneath the blade. This lower protruding
portion of
the stiffener thus serves as an air dam and the tendency for lift-off to occur
is
reduced.
In order to enhance the airfoil effect provided by the stiffener, the higher,
lateral edges of the stiffener as presented to the wind stream may extend
outwardly
from the opposite side of the blade. This extension may be greater than that
found in
the traditional parallel-sided stiffeners and greater than the extension on
the lower
side of the blade. The airfoil effect thereby provided will develop a force
tending to
press the wiper against the windshield. This extension of the stiffener's
width may be
tapered, narrowing towards the ends of the blade and widening towards the
center
portion.
An increase in widening of the stiffener on the upper side of the blade is
practical because there is space above the blade for this widening to occur.
Due to the
angling of the blade, such a widening is limited on the opposite, lower side
by the
proximity of the windshield surface. While the lower edge of the stiffener is
very
nearly straight when the wiper is deployed on a flat surface, it may have a
slight taper
as on the higher side, but preferably to a substantially lesser degree.
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To allow a connector to engage a beam blade at its center region, that region
of
the stiffener may optionally revert to the standard parallel width, permitting
the
connector to have a width that is closer to the standard width.
In accordance with the preferred variant of the invention, the stiffener is
mounted in slots along the sides of the body portion of the blade, with the
downstream slot being fonned in the body at a higher location along the
downstream
face that on the upstream face that is directed towards the wind stream.
This rearward downstream lateral face of the blade body may be solid, fonning
one side of a blade body having a triangular cross-section. Or it may contain
a
further longitudinal groove running the length of the blade. The presence of
such a
groove makes the body of the blade more flexible. Such groove may penetrate
into
the body of the wiper by approximately one third of the width of the blade
body. The
groove may be inwardly tapered with the bottom face of the groove being
parallel to
the underside surface of the main body portion of the blade, and the top face
of the
groove being parallel to the inner surface of the lateral slot fonned above
it.
In order to connect the wiper blade to the end of a wiper arm, a connector is
provided. Standard wiper anns generally terminate with a hook and/or
transverse pin
that extends parallel to the surface of a windscreen. Standard connectors
engaging
with such hooks/pins present a standard wiper blade to the windshield of a
vehicle so
that the central plane of the blade edge and backing support are generally
upright and
perpendicular to such windshield.
However, if a standard connector were used to couple a wiper blade according
to the invention to a wiper ann, then there may be a tendency for the blade
edge
deflection arising from a wiping action not to be symmetrical. Such a tendency
will
be resisted by the linkage between the end of the wiper arm and the connector.
If this
connection is not perfectly rigid some twisting in this coupling may occur.
Further,
lateral twisting can arise in the flexible body of the wiper blade. Unless the
central
wiping edge plane of the wiper is generally upright and perpendicular to a
windshield
(in the absence of contact with the windshield), the blade edge deflection
will not be
held to similar values irrespective whether the blade edge is being wiped in a
first or
second, reverse direction.
It is therefore desirable for the wiping edge of the wiper blade to be pressed
towards the windshield surface in a substantially upright, vertical, direction
and
preferably so that the pressing force passes through or near to the neck of
the blade
so as to minimize torque arising at the coupling between the connector and the
end of
the wiper ann.
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According to a further feature of the invention, a connector for connecting
the
wiper blade of the invention to a standard wiper ann is provided wherein the
connector is asymmetrically formed. Such connector engages the wiper blade by
connecting to the extending sides of the stiffener.
The asymmetry in the connector is adjusted to cancel the effect of the
asymmetry in the orientation of the stiffener within a wiper blade made in
accordance
with the invention. The combination of such an asymmetrical connector with a
wiper
blade that is asymmetrical in accordance with the invention serves to present
the
wiping edge of the wiper blade to a windshield with a nonnal, substantially
upright,
vertical, orientation.
Further, the angled connector is geometrically formed to engage the blade so
that the line of force generated by the pressure of the end of the wiper arm
lies within
or generally proximate and parallel to the central wiping edge plane of the
blade.
When a connector in accordance with a preferred variant of the invention is
shaped so that the pressing force supplied by the end of the wiper arm is
generally
directed along or close to the central wiping edge plane of the wiper blade,
this
reduces the tendency for an undesirable torque to be generated at the coupling
with
the wiper arm and reduces the tendency for an undesirable deflection to occur
in the
wiping edge.
Accordingly, the wiping edge is pressed against the windshield with a
balanced pressure which retains the desirable effect of having generally
similar
amounts of deflection arise irrespective of the direction that the wiper blade
is being
passed over a vehicle windscreen.
In the case of the beam-fonnat wiper, the stiffener is preferably in the form
of
a leaf spring that has a preset curvature to complement the curvature of a
windshield
surface and to overcome a lack of rigidity in the stiffener. This curvature
allows the
wiping edge of the wiper blade to bear against the windshield surface with a
greater
force towards the outer ends of the blade than would occur with a straight
blade.
With the selection of an appropriate degree of curvature, particularly where
the
curvature is concentrated in the central portion of the wiper, such a curved
beam-
fonnat wiper can apply a relatively similar force at the wiping edge over its
longitudinal length. The introduction of such an inherent curvature into the
stiffener
does not interfere with the function of the present invention and enhances the
performance of a wiper as constructed.
The foregoing suinmarizes the principal features of the invention and some of
its optional aspects. The invention may be further understood by the
description of
the preferred embodiments, in conjunction with the drawings, which now follow.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a front quarter perspective view of the hood and windshield of an
automobile showing the airflow over the windshield.
Figure 2 is a side view of an automobile showing the alignment of the
windshield with respect to the direction of the airflow.
Figure 2A is an enlarged end view of a wiper blade according to the invention
as oriented for contacting the windshield shown in Figure 2.
Figure 3 is a top quarter perspective view of the blade of the invention with
a
portion of the connector attached thereto showing the lateral wing or airfoil
provided
to the blade on one side by the stiffener fitted therein.
Figure 4 is a perspective view of the rubber blade forming part of the
assembly
of Figure 3.
Figure 5 is a top view of the blade of Figure 3 with the top, capping portion
of
the rubber blade body removed, exposing the stiffener.
Figure 6 is a side view of the blade of Figure 3 showing a generally constant
degree of curvature.
Figure 6A is a side view as in Figure 6 of a blade wherein the curvature is
focused in the center portion of the blade.
Figure 7 is a side view of the blade of Figure 3 having the shallow curvature
of
a blade of Figure 6 with a connector mounted thereto and poised over and above
the
windshield of a vehicle for engagement there with.
Figure 8 is a cross-sectional view of the rubber blade of Figure 4 with a
stiffener mounted therein positioned at the orientation of the blade of Figure
7 to the
windshield of a vehicle. The blade is shown without the edge deflection that
would
otherwise arise from the pressing force developed by a wiper ann.
Figure 9 is a cross-section taken through the center of the bottom half of the
connector as it is connected to the center of a wiper blade with the stiffener
in place
as depicted in Figure 8.
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Figure 9A is an alternate and enlarged detail of an alternate connection
between the connector and stiffener on one side of the connector.
Description of the Preferred Embodiments
In Figure 1 an automobile 1 with a windshield 2 advances through airflow 3
whereby the airflow 3 is deflected upwardly as it passes over the windshield
2. In
Figure 2 a wiper blade assembly 4 including a rubber blade body 5, stiffener 6
and a
connector 7 is positioned at the base of the windshield 2. In Figure 2A the
blade
edge 12 is angled with respect to the blade body 5 but is presented to the
windshield
in an upright orientation.
In Figure 3 the top surface or capping strip portion 10 of the blade body 5 is
shown protruding through the blade surface 6 in the same manner as in Figure
2A.
The bottom portion 7 of the connector 7 is depicted engaging the narrowed
portion of
the stiffener 6 in the central region of the blade 4. Only the blade-
connecting portion
of the connector 7 is shown. The wiper ann-connecting portion is omitted for
clarity.
The stiffener 6 is provided with a winged portion 11 on one side which, beyond
the
narrowing in the center portion, tapers to a smaller width towards the
respective outer
ends of the blade 4. The blade 4 with the stiffener has a natural,
unconstrained
curvature shown in greater detail in Figures 6 and 6A.
In Figure 4 the blade 4, generally made of rubber includes a longitudinally
extending body 5 capped with a top capping strip 10 in the form of a strip,
and
provided with a lower, longitudinally extending wiping edge 12. The wiping
edge 12
is supported as part of the blade by a longitudinally extending edge support
portion
13, generally and preferably having the shape in cross-section of an
arrowhead. The
edge support portion 13 is connected to the body 5 by a longitudinally
extending
neck 14.
The longitudinally extending stiffener 6 stiffens the flexible wiper blade 4.
In
the case of the beam-format wiper, the stiffener 6 is preferably in the fonn
of a leaf
spring that has a preset curvature to complement the curvature of a windshield
surface 2 and to overcome a lack of rigidity in the stiffener 6. This
curvature, shown
in Figures 6 and 6A, allows the wiping edge 12 of the wiper blade 4 to bear
against
the windshield surface 2 with a greater force towards the outer ends of the
blade 4
than would occur with a straight blade. This curvature, as shown in Figure 6,
may be
generally even along the length of the blade 4. Or the curvature may be
focused to
be highest in the central region of the blade 4, as shown in Figure 6A.
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As best shown in Figures 4 and 5, the stiffener 6 is fitted to the blade 4
through
engagement with a pair of mounting slots 15, 15A formed along the upper
portion of
the body 5 of the wiper blade 4. The mounting slots 15, 15A generally run
longitudinally down the body portion 5, along the length of the sides of the
wiper
blade. The top capping strip 10 of the blade 4 overlies in part the top
surface of the
stiffener 6, anchoring the parts together.
As shown in Figure 5, the stiffener 6 has a central, longitudinal, stiffener
slot
30 divided into two portions 30, 30A separated by a central bridge 31 joining
the two
sides of the stiffener 6. The width of these two stiffener slot portions 30,
30A
corresponds to the width of a corresponding, interrupted, "spine" 32 running
the
length of the rubber blade. This spine 32 within the rubber blade 4
constitutes the
separation between the two lateral mounting slots 15, 15A in the blade 4. The
spine
32 of the blade 4 is fitted into the two longitudinal slot portions 30, 30A on
the
stiffener 6 and is correspondingly interrupted in the center to accommodate
the
bridge 31. The top capping strip 10 is similarly divided into two sections 10,
10A.
In order to pennit the blade 4 to be engaged with the stiffener 6, the
respective
stiffener slots 30, 30A each has a short widening 33 that will admit a
respective
portion of the two capping portions 10, 10A to pass there through, allowing
the spine
32 to be slid into place within the stiffener slots 30, 30A along the full
length of the
blade 4.
The stiffener 6, when mounted for engagement with the lateral mounting slots
15 on the wiper blade 4, is of a width that causes edge portions of the
stiffener 6 to
extend outwardly from the sides of the body portion 5 of the wiper blade 4.
The
outward extending sides of the stiffener 6, particularly in the widened blade
portion
11, provide face surfaces areas that are useful in serving the function of an
airfoil.
By reason of the locations and orientations of the slots 15, 15A the stiffener
6
is mounted to the blade body 5 at an inclined angle. In a preferred embodiment
as
shown in Figure 8, the mounting slots 15, 15A are inclined at an offset angle
16 from
the central geometric plane 17, defined as a plane running the length of the
blade
which includes both the wiping edge 12 and the neck portions 14 of the wiper
blade 4
when the blade is extended in a straight line, free from contact with a
surface.
Thus the outer top surfaces 19 of the stiffener 6, which would normally, in
the
prior art, lie in a plane oriented at 90 to the surface of the central plane
17 of a wiper
blade 4, are offset by a predetermined offset angle 16 from such 90
orientation. The
capping top portion 10 of the wiper blade 4, when the stiffener 6 is mounted
along
the lateral sides of the blade body 5, is also preferably slanted in a similar
manner.
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CA 02583885 2007-04-04
Because the sides of the stiffener 6 extend outwardly from the sides of the
body portion 5 of the wiper blade 4, the offset angle 16 of the mounting slots
15
causes the face surfaces 19 of such extending side portions, (as well as the
top
capping strip 10 of the body 5 of the wiper blade 4), to be presented, when
mounted
on the windshield 2 of a car, so that such face surfaces 19 are more nearly
oriented
towards the direction of the travel of the vehicle. In this configuration,
such face
surfaces 19 (as well as the top capping strip 10) provide the function of an
airfoil.
A preferred value for the offset angle is 18 . However, this angle may fall
within the range of 5 to 45 , more preferably closer to 18 and subranges
there
within.
It is not essential for both sides of the stiffener 6 to be extended to
function as
an airfoil. The lower, leading, edge 35 of the stiffener 6 may be extended so
as to be
positioned closer to, and preferably evenly spaced from, the surface of the
windshield
2 when a wiper according to the invention is installed on a vehicle. This
serves to
reduce the space for the wind stream 3 to get beneath the blade 4, providing
an air
dam effect and the limiting tendency for lift-off to occur. While the lower,
leading
edge 35 of the stiffener 6 may be perfectly straight, it may also incorporate
a slight
taper, receding from the center portion of the wiper blade 4 when proceeding
towards
the outer ends of the blade 4.
The higher, lateral edges 36 of the stiffener 6 as presented to the wind
stream
may extend outwardly from the opposite side of the blade 4 to a degree that is
greater
than that found in the traditional parallel-sided stiffeners and greater than
the
extension in respect of the leading edge 35 of the blade 4. The airfoil effect
thereby
provided will develop a force tending to press the wiper 4 against the
windshield 2.
This extension 36 of the stiffener's width maybe tapered, narrowing towards
the ends
of the blade 4 when proceeding outwardly from the center portion.
Such widening is preferably provided to a greater extent along the higher side
of the blade being presented to the wind stream as shown in Figures 7 and 8.
In accordance with the preferred variant of the invention, the stiffener 6 is
mounted in slots 15, 15A along the sides of the body 5 of the blade 4, with
the
higher, downstream slot 15A being formed in the body 5 along its higher,
downstream or rearward side.
This rearward downstream lateral face of the blade body 5 may be solid (not
shown), forming one side of a blade body 5 having a triangular cross-section.
Or it
may contain a further longitudinal groove 24 running the length of the blade
4. In
13
CA 02583885 2007-04-04
the latter case, such a groove 24 can reduce the amount of rubber in the main
body of
the blade, rendering it more flexible.
Preferably, such a further longitudinal groove 24 is inwardly tapered,
tenninating at a root face at approximately one third of the distance across
the body 5
of the wiper blade 4, at approximately the same distance across the body 5 as
where
the arrowhead 13 will contact the base of the blade body 5 when deflected.
This
groove 24 introduces additional flexibility into the body 5, reducing
shuddering when
the blade is passed over a windshield 2.
In order to connect the wiper blade 4 to the end of a wiper, a wiper ann 25 is
equipped with a pin 26 which engages a connector 7 fastened to the blade 4, as
shown in Figures 7 and 9. The pressing force of the wiper ann 25 in the
direction 27
directs the pin 26 to move in the direction 27. This force is applied to the
blade body
5 through the connector 7.
The preferred connector 7 of the invention is asymmetrically shaped to press
the wiping edge 12 of the wiper blade 4 towards the windshield surface 2 in a
substantially upright, vertical, direction and preferably so that the pressing
force 27
passes approximately through the neck 14 and wiping edge 12 of the blade 4, or
parallel to that direction as shown in Figure 8. The line of force 27 so
generated by
the pressure of the end of the wiper ann 25 lies within or generally proximate
and
parallel to the central plane 17 of the blade 6. To achieve this, the
connector 7 is
asymmetrically formed so that the central plane 17 of the wiping edge 12
passes
approximately through the center of the connector 7 in the same direction as
the
applied force 27.
Such connector 7 engages the wiper blade 4 by connecting to the extending
sides of the stiffener 6. Tabs 28, 28A extending from the connector embrace
the
edges of the stiffener 6 fixing the connector 7 in place. The asymmetry in the
connector 7 is adjusted to cancel the effect of the asymmetry in the
orientation of the
stiffener 6 within the wiper blade 4. The combination serves to present the
wiping
edge 14 of the wiper blade 4 to a windshield 2 with a nonnal, substantially
upright,
vertical, orientation in the absence of deflection arising from wiper arm
pressure.
When a connector 7 in accordance with a preferred variant of the invention is
shaped so that the pressing force supplied by the end of the wiper ann 25 is
generally
directed along the central plane 17 of the wiper blade, this reduces the
tendency for
an undesirable torque to be applied to the portion 13 of the wiper blade
supporting
the wiping edge 12. Accordingly, the wiping edge 12 is pressed against the
windshield 2 with a balanced pressure which retains the desirable effect of
having
similar amounts of deflection arise irrespective of the direction that the
wiper blade 4
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CA 02583885 2007-04-04
is being passed over a vehicle windscreen. This arises because any tendency
for the
force 27 to develop a twisting torque about the blade body 5 is minimized.
A wiper according to the preferred embodiment of the invention as
manufactured may have the following typical dimensions. These dimensions
generally defined preferred ratios or proportions for the respective
components (all
dimensions are rounded-off or approximate):
- overall length of the rubber blade: 47 cm
- width of the central notched portion: 6.5 cm
- length of transitions to the central notched region: 1 cm
- offset angle: about 18
- taper of the leading, lower, edge of the stiffener from the center narrowing
towards the outer ends: about 0.9
- taper of the trailing, upper, edge of the stiffener from the center
narrowing
towards the outer ends: about
2 3/4
- length of the trailing, upper, edge of the stiffener from the outer end to
transition to the central notched region: 19.5 cm
- height of the neck; height of the spine; height of the forward, truncated,
leading edge of the blade body: all about 1 mm
- width of the rubber top capping strip: 7 mm
- width of the central slot in the stiffener: 2 mm
- maximum body width transverse to the central plane of the wiping edge: 10
mm
- protrusion of the neck and arrowhead edge support below the body of the
blade: 7 mm
- maximum outside width of the further longitudinal groove 24: 2 mm
- width of the inner root of the further longitudinal groove: 1 mm
- depth of the further longitudinal groove: 3 for mm
CONCLUSION
The foregoing has constituted a description of specific embodiments showing
how the invention may be applied and put into use. These embodiments are only
exemplary. The invention in its broadest, and more specific aspects, is
further
described and defined in the claims which now follow.
CA 02583885 2007-04-04
These claims, and the language used therein, are to be understood in terms of
the variants of the invention which have been described. They are not to be
restricted
to such variants, but are to be read as covering the full scope of the
invention as is
implicit within the invention and the disclosure that has been provided
herein.
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